Predicting Outcome of Labour Induction Using Sonographic Cervical Length and Bishop Score at University of Ilorin Teaching Hospi

Home , Bishop score

PREDICTING OUTCOME OF LABOUR INDUCTION USING SONOGRAPHIC

CERVICAL LENGTH AND BISHOP SCORE AT UNIVERSITY OF ILORIN

TEACHING HOSPITAL

A DISSERTATION SUBMITTED TO THE NATIONAL POSTGRADUATE

MEDICAL COLLEGE OF NIGERIA IN PARTIAL FULFILLMENT OF THE

REQUIREMENT FOR THE AWARD OF THE FELLOWSHIP OF THE COLLEGE

TITLE PAGE

DR RAJI-OLARINOYE SEKINAT TITILAYO MB;BS Ilorin, 2008

NOVEMBER 2017

DECLARATION

CERTIFICATION

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DEDICATION

This work is dedicated to the memory of my Dad, Mr. Bashir Adekunle Raji. When you look down, I hope you’re proud of us.

And to my mum, the strongest woman I’ve ever known, Mrs. Ibirinade Funso Raji, for showing us in words and in deeds, the virtues of hard work and self-discipline.

ACKNOWLEDGEMENTS

I thank the almighty Allah for giving me the inspiration and grace to write this project. I am grateful to my supervisors Dr Adesina K. T., Dr Olarinoye A. O. and Dr Akande H. J. for their time, patience and invaluable input in the conduct of this study. I appreciate all consultants and residents of the Obstetrics and Gynaecology department, my research assistants, Dr Lola Owolabi, Nurse Fabiyi and my friend, Dr Aminat Ahmed.

To my lovely sons, Mudathir and Iqbal, thank you for patiently enduring my long absences from home and bravely competing with my laptop for my attention. My profound appreciation also goes to my mum, siblings, in-laws and help for taking care of my home and kids. To my darling husband Gboyega, my all time support, I say thank you for always having my back. May the good Lord bless you all.

ABBREVIATIONS

AUC Area under the curve

CI Confidence interval cm centimetres fFN Fetal fibronectin

IOL Induction of labour

LMP Last menstrual period

LR Likelihood ratio mm millimetres

OR Odds ratio

PG Prostaglandin

ROC Receiver Operating Characteristic

SD Standard deviation

SPSS Statistical Package for Social Sciences

TVS Transvaginal sonography

UITH University of Ilorin Teaching Hospital

USS Ultrasound scan

Vs Versus

WHO World Health Organisation

TABLE OF CONTENTS

TITLE PAGE ...... i

DECLARATION ...... ii

CERTIFICATION ...... iii

DEDICATION ...... iv

ACKNOWLEDGEMENTS ...... v

ABBREVIATIONS ...... vi

TABLE OF CONTENTS ...... vii

LIST OF TABLES ...... x

LIST OF FIGURE...... xi

ABSTRACT ...... xii

CHAPTER ONE: INTRODUCTION ...... 1

CHAPTER TWO: JUSTIFICATION ...... 4

CHAPTER THREE: LITERATURE REVIEW...... 6

3.1 Search Strategy ...... 6

3.2 General Overview and Historical Perspectives ...... 6

3.3 Physiologic Basis of Cervical Ripening ...... 9

3.4 Cervical Assessment ...... 10

3.5 The Bishop Score ...... 11

3.6 Sonographic Cervical Length for Pre-Induction Cervical Assessment ...... 14

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3.7 Comparing Bishop Score with Sonographic Cervical Length ...... 15

CHAPTER FOUR: AIM AND OBJECTIVES ...... 19

4.1 Aim ...... 19

4.2 Specific Objectives ...... 19

4.3 Hypotheses ...... 19

CHAPTER FIVE: MATERIALS AND METHODS ...... 21

5.1 Setting ...... 21

5.2 Study Population ...... 22

5.3 Study Design ...... 22

5.4 Sample Size Determination...... 23

5.5 Patient Recruitment ...... 24

5.6 Procedure ...... 24

5.7 Outcome Measures...... 29

5.8 Data Analysis ...... 30

5.9 Strengths ...... 31

5.10 Limitations ...... 32

CHAPTER SIX: RESULTS ...... 33

CHAPTER SEVEN: DISCUSSION, CONCLUSIONS AND RECOMMENDATIONS 47

7.1 Discussion ...... 47

7.2 Conclusions ...... 51

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7.3 Recommendations ...... 52

REFERENCES ...... 53

APPENDIX I: INFORMATION SHEET FOR PROSPECTIVE PARTICIPANTS...... 62

APPENDIX II: CONSENT FORM ...... 64

APPENDIX III: STUDY PROFORMA FOR DATA COLLECTION ...... 65

APPENDIX IV: BISHOP SCORE ...... 69

APPENDIX V: PAIN NUMERICAL RATING SCALE ...... 70

APPENDIX VI: ETHICAL APPROVAL ...... 71

LIST OF TABLES

Table 1: Sociodemographic and obstetric variables of the study population ...... 36

Table 2: Cervical assessment in the study population ...... 38

Table 3: Sensitivity and Specificity for Sonographic cervical length in predicting successful

induction in the study population (Criterion values and coordinates of the

ROC curve) ...... 40

Table 4: Sensitivity and Specificity for Bishop score in predicting outcome of induction of

labour in the study population (Criterion values and coordinates of the ROC curve) . 40

Table 5: The relationship between cervical parameters and some outcome measures with

successful and failed induction in the study population ...... 41

Table 6: Linear correlation of cervical assessment methods with some outcomes ...... 42

Table 7: Regression analysis of predictors of successful labour induction ...... 43

Table 8: Comparison of sonographic cervical length and Bishop score with outcome

measures ...... 44

Table 9: Comparing the sensitivity, specificity, positive predictive value, negative predictive

value, false positive and negative rates of the optimum sonographic cervical length

and Bishop Score ...... 46

LIST OF FIGURE

Figure 1: ROC Curves of Sonographic cervical length and Bishop score in predicting

successful induction ...... 39

ABSTRACT

Introduction: Failed induction is associated with increased maternal and perinatal morbidity and increased need for operative deliveries. The pre-induction cervical status is the most important determinant of induction success. The traditional Bishop scoring system used in the assessment of cervical status has come under some criticism and newer methods such as sonographic cervical length measurements are being offered.

Aim: To compare the accuracy of transvaginal sonographic cervical length with Bishop score in predicting outcome of induction of labour using misoprostol.

Methods: This was a prospective study involving 133 women admitted at term and beyond for induction of labour with misoprostol at the Obstetrics Department of University of Ilorin

Teaching Hospital between August 2016 and March 2017. Interviewer-administered, pretested proforma were used to collect data. Subjects had sonographic and digital cervical assessment for cervical length and Bishop score respectively. The pain score associated with each method was obtained. Induction outcomes were recorded. Successful induction of labour was defined as vaginal delivery occurring within 24 hours of onset of induction.

Statistical analysis was done using SPSS (version 21.0; Chicago, Illinois, USA). Analyses were by t-test, Chi-square, Pearson’s correlation, receiver–operating characteristics (ROC) curves and multivariate logistic regression.

Results: The mean sonographic cervical length was 25.19 ± 10.09 mm (range 0- 44 mm) and was 8mm higher than mean cervical length on digital palpation (p <0.001). Successful induction occurred in 78.9% of patients while 21.1% had failed induction. The mean Bishop score was 3.71 ± 1.98. The mean induction-delivery interval was 15 hours 38 minutes ± 13 hours 06 minutes (range = 4 hours 23 minutes - 94 hours 23 minutes). Bishop score, parity and birth weight independently predicted successful induction of labour. The Bishop score had a linear correlation with the induction-delivery interval (r = -0.267, p = 0.002). The

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sonographic cervical length did not have a linear correlation with successful induction or the induction-delivery interval. Analyses of the ROC curves showed that the Bishop score predicted successful labour induction better than sonographic cervical length (area under the curve 0.6617 vs 0.6199, p = 0.0046 vs p = 0.059). The optimum cut-off values for predicting successful induction of labour were sonographic cervical length and Bishop score of ≤24mm and >4 respectively. At these cut-offs, Bishop score showed a higher specificity (82.1% vs

78.6%) and positive predictive value (90.9% vs 90.2%) while sonographic cervical length showed a higher sensitivity (52.4% vs 47.6%) and higher negative predictive value (30.6% vs

29.5%). More than 90% of subjects had successful vaginal delivery at these cut-off points.

Sonographic cervical length measurement was significantly less painful (mean difference in pain score 3.47, p = <0.001) and was more acceptable (65.3% of subjects).

Conclusion: Bishop scoring system is more accurate than sonographic cervical length in predicting successful labour induction in women at term and beyond undergoing induction of labour with misoprostol. Sonographic assessment is less painful than digital cervical assessment. Bishop score > 4 and sonographic cervical length ≤ 24mm predict success in women undergoing induction of labour with misoprostol.

Recommendation: When induction of labour with misoprostol is planned, Bishop score should be used for pre-induction cervical assessment. Further studies in the form of randomized controlled trials are warranted.

Keywords: induction of labour, bishop score, sonographic cervical length.

Word Count: Introduction = 710 words. Literature Review = 3, 659 words. Aims and

Objectives = 112 words. Methodology = 2, 601 words. Strengths and Limitations = 305 words. Results: 812 words. Discussion, conclusion and recommendations: 1, 751. Total

Word Count: 10, 722.

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CHAPTER ONE

INTRODUCTION

Induction of labour (IOL) is the artificial initiation of labour after the age of viability but without any objective evidence of labour and with intact fetal membranes1, 2. It is a common obstetric procedure with an incidence ranging between 5 and 30% 3 - 7. It is performed for varying maternal and fetal obstetric and medical conditions. IOL is generally done when the risks to the mother and/or fetus of continuing pregnancy outweigh those of terminating the pregnancy4. The commonest indication for IOL is prolonged pregnancy4, 8.

Though IOL is a safe and efficacious mode of vaginal delivery, it is not without complications. Compared with spontaneous onset of labour, induction of labour is complicated by a higher rate of caesarean section, uterine tachysystole, abnormal fetal heart rate patterns, operative vaginal delivery, uterine rupture, perinatal asphyxia and increased

NICU admissions2, 5, 9 - 12. In some patients, indication for induction of labour is clear cut and expedient; in others, the indication is relative and the timing is controversial. Examples of the latter include post-dated pregnancy and some medical conditions in pregnancy. In such scenarios, IOL is best done at a time when it is likely to succeed and if the risks of the process to the mother and / or fetus are acceptable4. The risk of IOL resulting in caesarean delivery is significantly influenced by the pre-induction status of the cervix4, 8, 11.

As term approaches, the cervix prepares itself for spontaneous onset of labour by becoming softer and shorter, moving forward and starting to dilate3. Traditionally, the Bishop score has been used to assess the favourability of the cervix and predicts success of IOL2, 4, 13 - 15. Also, it is used to assess the need for cervical ripening. It is calculated based on five parameters.

These are cervical position, cervical consistency and station of the fetal presenting part, cervical effacement, and cervical dilation1, 2, 4. The maximum score is 13 and studies have

shown that women with a score of nine or more were more likely to have successful labour induction1, 16. Other studies demonstrated that 90% of women with a score ≥ 6 achieved vaginal delivery within six hours whereas, the course of labour was unpredictable in women with a score less than six1, 16. However, the Bishop score is a subjective criterion with inter- and intra-observer variability 3, 8, 15, 17. Digital examination may fail to assess the supravaginal portion of the cervix and effacement may be difficult to determine in the closed cervix1, 17 - 20. Palpation may underestimate cervical length by up to a centimeter or more21. It is however cheap and requires little or no extra cost to the patient.

Transvaginal sonographic cervical length measurement is an objective and easily reproducible measurement1, 5, 7, 18 - 20. It can objectively assess the supravaginal portion of the cervix and can be utilized even with a closed cervix and causes less discomfort20. TVS can be further used to assess cervical funneling and posterior cervical angle which have also been shown to predict induction outcomes1. In addition, TVS can provide pictorial evidence of the measured cervical length which can be filed for future reference. In the developed world where litigations are rife, this could serve as medicolegal evidence. The Nigerian society is increasingly becoming litigious and this may come in handy in the future. In contrast, the

Bishop score measurement once done cannot be independently confirmed without repeating a vaginal examination. TVS has also been shown to be less painful and better tolerated than digital cervical examination for Bishop Score20, 22. Studies have been done comparing this method with the Bishop score with conflicting results1, 17. While some have demonstrated its superiority over that of Bishop score5, 15, others have failed to do that 20, 22- 24.

This study compared the accuracy of transvaginal sonographic cervical length with Bishop score in predicting successful induction of labour in Ilorin. The results will add to the existing body of knowledge and further guide clinicians in choosing the more accurate method of

cervical assessment for better patient management. It also compared pain scores and acceptability of TVS with digital examination. This can help in better counseling of patients on options available to them and could help guide their choice.

CHAPTER TWO

JUSTIFICATION

Induction of labour is increasingly being practiced in modern obstetrics to improve pregnancy outcome for both mothers and babies. However this important procedure is not without attendant risks which may lead to recourse to caesarean delivery for failed induction. A retrospective study of 1,510 cases of induction of labour in Ogoja showed a failed induction rate of 24.1%25. In University of Ilorin Teaching Hospital (UITH), failed induction of labour was the 3rd most common indication for caesarean section accounting for 10.7%26. It is therefore important to be able to accurately predict those pregnancies with a likelihood of successful induction of labour.

The pre-induction cervical status is the most important parameter for predicting success of

IOL. Successful vaginal delivery is more likely with a ripe than an unripe cervix. The Bishop

Score which has been used traditionally for assessing pre-induction cervical status is plagued with problems of subjectivity and inter- and intra-observer variation3, 8. This has led to a search for more accurate, objective and easily reproducible means of assessing the cervix.

Sonographic measurement of cervical length via the transvaginal route has shown promise in predicting success of IOL with reasonable accuracy 7, 15, 19, 20. It measures more objectively the cervical length even when the cervical os is closed. It has been shown to be less painful or discomforting20. Unlike the Bishop score, it can also provide hard copy documentation of the cervical status at the time of examination which can be used for medico-legal purposes.

Concerns have however been raised concerning its cost, invasiveness and acceptability to patients.

While studies have been done comparing both methods in terms of superiority; the results have been inconclusive 5, 15, 20, 22-24. More studies need to be done in other to add to the

existing body of knowledge. Availability of such evidence from this and future studies will aid clinicians in choosing the more appropriate method of cervical assessment to improve induction outcomes.

Ilorin is a conservative society and there are concerns that TVS may be regarded as invasive and may be unacceptable to patients. While digital vaginal examination is also invasive of patient’s privacy, it has long been accepted by the majority of patients. Same cannot be said of TVS which is relatively new in this clime. Majority of the studies comparing sonographic cervical assessment and Bishop score were done in developed countries where acceptability of TVS is taken for granted. This study assessed the issue of acceptability of TVS compared to digital examination for pre-induction cervical assessment.

CHAPTER THREE

LITERATURE REVIEW

3.1 Search Strategy

The following electronic data bases were searched: Pubmed, Google Scholar, Medline and the Cochrane Database of Systematic Reviews using the search phrases ‘pre-induction cervical assessment’ and ‘prediction of successful labour induction’. The reference lists of retrieved articles were further analysed to identify relevant papers. Seventy-five full length articles were identified and reviewed. Thirty-two of those that analysed Bishop score, sonographic cervical length or both were utilized. An abstract that contained sufficient information was included. Those studies published in languages other than the English language were excluded.

3.2 General Overview and Historical Perspectives

Historically, the need to time delivery has been recognized for centuries. Methods such as the issue of threats, incantations, chants and potions were practiced and later, quinine and castor oil27 and a mixture of juniper berries, cinnamon, and castor oil were recommended to expedite birth28. In 1906, Henry Dale discovered that a preparation from ox pituitary tissue initiated uterine contractions in a pregnant cat29. Bell in 1909 subsequently described the clinical use of pituitary extract in pregnant women for the management of normal labour and uterine atony postpartum30. However, the use of oxytocin for IOL was first described by

Theobald and associates in 194831.

Other methods used in the past include Galvinism (stimulation of uterine contractions with electric current), repeated pressurized douches, extra-amniotic aqua pica, tents, bougies and catheters27. Some traditional methods are still indulged in till date despite lack of evidence of their effectiveness. These include administration of enemas and laxatives, vaginal sexual

intercourse, and exercise27. Modern methods in use today include membrane stripping, amniotomy alone or with oxytocin infusion and administration of prostaglandins and its analogues27, 32, 33.

Induction of labour is widely used in modern obstetrics in those situations where prompt delivery is necessary to reduce the risk of maternal and/or neonatal morbidity and mortality.

It is performed for a wide range of maternal and fetal conditions such as prolonged pregnancy, hypertensive disorders, diabetes mellitus, oligohydramnios, intrauterine fetal death, intrauterine growth restriction amongst others32, 33.

The rate of induction of labour varies from country to country and even between regions in the same country. In Maiduguri, it was quoted as 6.6% of all deliveries34and 11.5% in Cross

Rivers State25. A study in Kinshasha, DR Congo reported a rate of 3.2%35 while a pan

African study involving 7 countries reported rates of induction ranging between 1.4 and 6.8% with an average of 4.4%36. The rates are however, higher in developed countries with more than 22% of women undergoing IOL in the United States31 and 20% of women undergoing

IOL in the United Kingdom32. In developed countries, well defined national protocols and guidelines exist for the conduct of induction of labour; this may have contributed to the increased use of IOL in such countries. Also, well defined protocols for the management of medical complications of pregnancy such as hypertension and diabetes recommend increased use of IOL at term to optimize perinatal outcomes.

Close fetomaternal monitoring is required during the induction process thus putting a strain on the already limited resources in developing countries. These may contribute to the low induction rates in developing countries. Also contributory, is the cultural aversion to obstetric interventions in developing countries where women may prefer spontaneous onset labour 37,

38.

The aim of IOL is to achieve vaginal delivery with minimal risk to mother and baby. There is no consensus on the definition of successful IOL. Some authors define it as successful vaginal delivery within 24 hours of onset of induction regardless of the induction method used3, 15, 23. Regardless of the definition used, successful IOL has been shown to improve pregnancy outcome. In post-term pregnancies (the most common indication for IOL), increasing use of labour induction reduces caesarean section rates without increasing other pregnancy complications39, 40. This is especially important in developing countries such as

Nigeria where resources are scarce and there may be a cultural aversion for caesarean section37, 38. Also, in Canada, the stillbirth rates decreased over a 15 year period following an increased rate of IOL for post-term pregnancies41. IOL also improves perinatal and maternal outcomes in women with medical complications of pregnancy. A study showed a doubling of stillbirth and perinatal deaths in women with medical complications of pregnancy who did not have IOL compared with those who did35. Compared to expectant management, IOL has been shown to improve maternal outcomes in women with gestational hypertension and mild preeclampsia at term42.

As with successful induction, there is no consensus on the definition of failed IOL1, 32. NICE defines it as failure to establish labour following one cycle of treatment with prostaglandin analogues32. Different criteria have been used in different studies making comparison difficult. Failure of vaginal delivery from within 24 to 96 hours has been used depending on the author or the local/institutional protocol22 - 24. Failed IOL is associated with potential risks and complications. These include increased risks of uterine tachysystole, abnormal fetal heart rate patterns, operative vaginal delivery, caesarean birth and uterine rupture1, 31, 32, 34.

Compared to spontaneous onset labour, IOL is associated with higher caesarean section rates2, 5. Neonatal admission rates of up to 12% have been quoted following IOL43, 44.

Therefore, it is important to carefully select patients for IOL and to accurately predict success

of IOL. To mitigate these risks, several maternal and fetal factors as well as screening tests have been suggested to predict success of labour induction. They include parity, past obstetric history, maternal height, weight, body mass index and maternal age, Bishop score and its individual components, fetal factors such as birth weight and gestational age, transvaginal ultrasound assessment of the cervix, and biochemical markers such as fetal fibronectin (fFN) and insulin-like growth factor binding protein-1 (IGFBP-1)1, 8.

3.3 Physiologic Basis of Cervical Ripening

The uterine cervix serves two major functions in pregnancy. First it maintains its physical integrity and remains firmly closed as the uterus enlarges. This maintains the growing fetus in-utero until the appropriate time for delivery. In contrast, as labour approaches, it must undergo changes to become soft, easily distensible and yielding to allow delivery of the fetus45, 46.

The uterine cervix is histologically distinct from the corpus uteri as it consists mainly of connective tissue and little muscle tissue. The connective tissue is made up of dense bundles of types I and III collagen embedded in a ground substance consisting of large molecular weight proteoglycan molecules. The predominant glycosaminoglycans in the cervix are chondroitin sulphate and dermatan sulphate; others are heparin sulphate, dermatan, chondroitin and hyaluronic acid45.

However, in the last few weeks of pregnancy, a change occurs in the relative content of cervical glycosaminoglycans. An increase in the concentration of the hydrophilic hyaluronic acid attracts water molecules making the cervix softer. A decrease in the concentration of chondroitin and dermatan sulphate leads to rearrangement of collagen fibres into a looser network and a reduction in the tensile strength of the cervix. There is also an increase in

cervical collagenase activity leading to cervical collagen degradation. The net effect of these changes is a softer and more pliable cervix45.

Prostaglandin E2 (PG E2) has been implicated in the causation of cervical ripening. It causes vasodilation of cervical capillaries and increase in their permeability to circulating neutrophils leading to extravasation of large quantities of neutrophils into the cervical stroma under the chemoattractant influence of IL-8 45, 46. The neutrophils degranulate releasing collagenolytic enzymes responsible for degrading cervical collagen. Monocytes are also recruited into the cervix during cervical ripening under the influence of MCP-1 and serve as a source of both prostaglandins and IL-845, 46.

The role of prostaglandins in stimulation of labour is not only limited to cervical ripening; they are also strong myometrial stimulants and increase the sensitivity of the myometrium to oxytocin. They are thus used extensively for cervical ripening and induction of labour and have been shown to be highly effective 31, 32. Systematic reviews have shown that compared with placebo and intravenous oxytocin, IOL with prostaglandins has a higher chance of achieving vaginal delivery within 24 hours, a lower chance of caesarean delivery and a lower risk of neonates with Apgar score less than 7; it is however associated with a higher risk of uterine hyperstimulation and fetal heart rate changes 47 - 49. Misoprostol induction is the commonest method used for cervical ripening and IOL in this centre and this study will be limited to patients undergoing IOL with said method.

3.4 Cervical Assessment

Successful labour induction has been clearly shown to be related to the state of the cervix18, 34,

50; thus assessing cervical status prior to induction of labour is fundamental. Several investigators have worked on developing methods and scoring systems for assessing the cervix. Calkins et al in 1930 studied the factors influencing the duration of the first stage of

labour and concluded that the length and consistency of the cervix were significant predictors51. In 1964, Bishop introduced his scoring system which has remained the traditional method of cervical assessment for labour induction 52. A modified Bishop scoring system was later developed where the cervical effacement was replaced with cervical length53. In recent times, research has focused on the use of transvaginal sonographic cervical length and fetal fibronectin (FFN) levels in cervicovaginal secretions in assessing the state of the cervix 1, 24.

3.5 The Bishop Score

Since 1964, when Edward H. Bishop first introduced his “pelvic scoring system for elective induction”52, the Bishop score has been the standard, most widely used method for pre- induction cervical assessment54. Bishop’s subjects were consenting multiparous women at 36 weeks gestation and above, with vertex presentation and with no obstetric complication in past or index pregnancies. Induction of labour in modern obstetrics has however spread to include nulliparous women as will be done in this study. Bishop assessed five different parameters which include the cervical dilatation, consistency, position, degree of effacement and station of presenting part. These parameters were given numerical values with a maximum score of 137, 49, 52.

Bishop concluded in his study that at a score of 9 and above, induction of labour was safe and successful. Scores below this led to increased risk to mother and fetus, longer duration of labour and decreased chances of success52. Over the years, attempts have been made to modify and/or simplify the Bishop score. Burnett in 1966 used the same parameters but each was scored 0, 1 or 2 and the maximum score was 10 as shown below55. His study also revealed that a Bishop score of 6 or more was favourable for IOL16, 55, 56.Generally, a Bishop score of 6 or more is taken as favourable for IOL32.

Bishop Pelvic Score52

Score 0 1 2 3

Dilatation (cm) Closed 1 – 2 3 – 4 5 -6

Effacement (%) 0 – 30 40 - 50 60 - 70 80

Consistency Firm Medium Soft -

Position Posterior Middle Anterior

Station -3 -2 -1, 0 +1, +2

Modified Bishop Score

Score 0 1 2

Dilatation (cm) <1.5 1.5 – 3 ≥3

Effacement Uneffaced ≥1.5 Intermediate Effaced ≤0.5

Consistency Firm Intermediate Soft

Position Posterior Middle Anterior

Station ≥-2 -1 ≤0

Some authors have shown that not all parameters of the Bishop score are important in predicting success of IOL and as such, they do not need to be routinely assessed. Reis et al found that only cervical dilatation and effacement were significantly associated with delivery within 24 hours24. They devised an abbreviated Bishop score from these two parameters with a score of 2 being the best cutoff for successful induction24. Recently, Laughon et al in a study involving 5,600 nulliparous women undergoing induction of labour found that a simplified Bishop score, including only cervical dilation, effacement, and station, was equally as predictive as the traditional Bishop score in predicting vaginal delivery57. Pandis et al found that the cervical length was the only component of the Bishop score that significantly contributed to predicting successful vaginal delivery within 24 hours of induction15.

Assessing the cervix digitally using the Bishop Score has obvious advantages. It is simple, safe, does not require any sophisticated equipment and is thus cheap. It has also been shown to correlate well with success of labour induction58. In one study, each unit of increase in the

Bishop’s score was associated with a 1.86-fold increase (95% CI 1.06 - 3.26) in the likelihood of a successful induction23. In a study, agreement between two observers assessing the Bishop score was fair to substantial; the observed differences were clinically acceptable.

Agreement was however lower for individual components of the Bishop score59. In the study, perfect agreement between two observers was only 28%. Accepting a difference of one point between the observers, agreement increased to 66% 59. Other authors found these figures low and conclude that the inter-observer difference is significant3, 5.

Assessing the cervix digitally may however be inaccurate as the supravaginal part of the cervix may not be palpable if the cervix is closed. Also, digital vaginal examination has been shown to underestimate cervical length by up to a centimetre or more21.

A systematic review of 40 studies involving 13,757 subjects showed that the Bishop score had poor predictive capacity for caesarean delivery following IOL60.

3.6 Sonographic Cervical Length for Pre-Induction Cervical Assessment

Since the classic 1958 work of Ian Donald et al which profiled the first obstetric sonographic images, use of obstetric ultrasonography has evolved to include diagnosis of early pregnancy complications, accurate pregnancy dating, diagnosis of multiple gestation and fetal anomalies, placental localization, fetal biometry, fetal activity and cervical studies to diagnose cervical incompetence, predict preterm birth and outcome of labour induction etc61.

Sonographic cervical length measurement is being promoted as an alternative tool for cervical assessment. This is because with the transvaginal scan, the entire length of the cervix can be visualised regardless of whether the cervix is open or close; this confers an obvious advantage.

Sonographic cervical length has been shown to be an independent predictor of caesarean delivery following IOL19,20, 58. A study in Baghdad showed that women with cervical length ≤

30 mm had shorter duration of labour and were more likely to deliver vaginally than women who had cervical length greater than 30 mm19. The best cut-off point of cervical length for predicting successful labour induction was 20mm and 28mm in the studies by Tan et al20 and

Pandis et al15 respectively. A systematic review of 31 studies to assess the predictive capacity of sonographic cervical length for outcome of IOL showed moderate capacity. The overall sensitivity and specificity for predicting caesarean delivery ranged from 0.35 to 0.92 and 0.35 to 1 respectively62.

Concerns have been raised concerning the acceptability of TVS in pregnant patients. Clement et al, in a cross-sectional study of antenatal clients, compared acceptors of TVS with non- acceptors. About 86% of the acceptors expressed willingness to have another TVS in a future

pregnancy. The majority of patients did not find it a difficult experience as the average level of difficulty was 1.3 on a scale of 0 to 563. Many found it easier than taking a cervical smear and venepuncture but a more difficult experience than a transabdominal scan63.

Approximately 37% of the women experienced some pain or physical discomfort; however majority described the pain as mild or discomforting.

3.7 Comparing Bishop Score with Sonographic Cervical Length

A number of studies have been done to compare accuracy of Bishop score with that of sonographic cervical length in predicting success of labour induction or otherwise 7, 10, 15, 22, 24.

Both Bishop score and sonographic cervical length have been shown to correlate with duration of labour19, 58. A linear correlation has been shown between the sonographic cervical length and Bishop score19. However, questions have been raised on the superiority of one method over the other.

Bastani et al compared the value of TVS findings and Bishop score in predicting caesarean section following induction of labour. The Receiver Operating Characteristics (ROC) curve showed that sonographic cervical length had a higher Area under the curve (AUC) than the

Bishop score (0.69 versus 0.39)7. The study used a sample size of 200 which is relatively large. Other studies have shown cervical length to be a better predictor of successful induction of labour than the Bishop score9, 10, 15. Pandis quoted a sensitivity of 0.87 and a specificity of 0.71 for sonographic c ervical length compared to 0.58 and 0.77 for Bishop score15. The Kaplan–Meier survival curves indicated that better discriminatory results in the prediction of vaginal delivery within 24 hours were achieved using cervical length rather than the Bishop score15. In the cited study, digital assessment was carried out by the attending obstetrician or midwife. While the risk of bias was eliminated by blinding the clinician to the

sonographic findings, inter-observer variations might have affected Bishop score assessment and consequently its predictive value.

Park, in his study on nulliparous women showed that sonographic cervical length, but not the

Bishop score, significantly and independently predicted failed induction of labour5. Another study showed that both Bishop score and sonographic cervical length correlated well with duration of labour but the latter was less subjective and was a better predictor19.

On the other hand, some studies have shown that the Bishop score had better accuracy than sonographic cervical length22, 24. A study by Chandra on post-term pregnancy concluded that transvaginal ultrasound does not predict vaginal delivery as well as digital cervical examination22. In his study, only the Bishop score (odds ratio [OR] 2.98, 95% confidence interval [CI] 1.71-5.20), cervical position (OR 4.35, 95% CI 1.41-12.50), and maternal age

(OR 1.15, 95% CI 1.01-1.30) independently predicted any vaginal delivery22. Reis et al found that the likelihood ratio for predicting vaginal delivery within 24 hours of labour induction was 2.61 with a favourable cervix compared with 1.61 with sonographic cervical length24. Reis et al24 and Gonen et al54 found that the Bishop score could independently predict successful labour induction while sonographic cervical length could not.

In the above studies, there was no standardized method of labour induction; the choice of prostaglandin analogue, amniotomy alone or synchronous amniotomy with oxytocin was left to the discretion of the physician. This might have independently affected outcomes such as induction to active phase interval, induction to delivery interval and neonatal outcomes.

Cengiz et al used dinoprostone (PG E2) as the sole method of induction in all subjects. They found that the Bishop score was a better predictor of failed IOL than sonographic cervical

23 length . Misoprostol (PGE1) analog was used as the sole method of labour induction in this study.

Tan et al found that sonographic cervical length was as good as Bishop score in predicting caesarean delivery following IOL20 similar to the findings in the study by Rane10. The Area under the Curve (AUC), sensitivity, specificity, positive and negative predictive values for the former method were marginally higher but their confidence intervals overlapped20. This study further compared patients’ tolerability of both methods. Transvaginal sonography was signiﬁcantly less painful than digital examination for Bishop score assessment (mean difference in Visual Analog Score was 3.46; P < 0.001)20. Majority of the subjects (86.3%) found transvaginal assessment to be less uncomfortable, 16.4% found both procedures to be equally tolerated and 7.2% felt that transvaginal assessment was more uncomfortable than digital assessment for Bishop score20.

Another study by Tan et al compared Bishop score, TVS cervical assessment and clinical factors as predictors of newborn admission following IOL. Following multivariate logistic regression analysis, only Bishop score <5 and caesarean delivery were independent predictors for NICU admission. Sonographic cervical length >20mm was not significant44.

A recent meta-analysis compared Bishop score with other methods of cervical assessment. It included two randomized controlled trials of moderate quality involving 234 women. Results showed that the women that were randomized to the transvaginal sonography (TVS) arm had more need for misoprostol for cervical ripening. There was however no statistically significant difference in the two arms in predicting vaginal birth, caesarean delivery, neonatal admission into the neonatal intensive care unit (NICU), meconium staining of the amniotic fluid, fetal heart rate abnormalities and low Apgar score. The study concluded that there was no difference in induction outcomes between the two arms of the study and suggested that both Bishop score and sonographic cervical length measurement could be complementary1.

Previous research has focused on comparing the predictive capacities of digital and sonographic cervical assessment; in addition to this, a few compared subjects’ perception of pain or discomfort during cervical assessment with both methods. There is a paucity of studies evaluating patients acceptance of TVS compared to digital assessment. This was included in the present study.

Most methods of induction of labour require digital vaginal examination either for administration of the induction agent or amniotomy; Bishop score assessment can be done at the same examination without additional discomfort to the patient. On the other hand, sonographic cervical assessment would be an added intervention to the induction process where it is the method employed for cervical assessment; this has led to some authors recommending it for cervical assessment prior to induction of labour by the oral route alone20.

Transvaginal sonography is not readily available in developing countries such as ours. The equipment and requisite skills may not be found outside tertiary health centres. This may serve as a deterrent to the routine use of TVS for preinduction cervical assessment even if it is shown to be of superior accuracy. However, it is hoped that with future improvement in health care delivery in Nigeria, TVS will be readily available for the management of both obstetric and gynaecologic cases.

CHAPTER FOUR

AIM AND OBJECTIVES

4.1 Aim

To compare the accuracy of transvaginal sonographic cervical length measurement with that of Bishop score in predicting successful induction of labour using misoprostol.

4.2 Specific Objectives

1. To measure the cervical length using transvaginal scan among pregnant women

at 37 weeks gestation and above planned for IOL with misoprotol.

2. To determine the sonographic cervical length for predicting successful IOL at 37

weeks and above.

3. To assess the accuracy of sonographic cervical length measurement in predicting

outcome of induction of labour and to compare it with that of Bishop Score.

4. To compare the pain scores in these women during cervical assessment with

vaginal transducer and digital examination.

4.3 Hypotheses

Null Hypothesis

There is no difference in the accuracies of transvaginal sonographic cervical length measurement and Bishop score in predicting success of labour induction with misoprostol.

H0:푝1 = 푝2

Alternate Hypothesis

There is a difference in the accuracies of transvaginal sonographic cervical length measurement and Bishop score in predicting success of labour induction with misoprostol.

H1:푝1 < 푝2

H1:푝1 > 푝2

CHAPTER FIVE

MATERIALS AND METHODS

5.1 Setting

The study was conducted in the Department of Obstetrics and Gynaecology, University of

Ilorin Teaching Hospital (UITH), Ilorin, Kwara State, Nigeria. UITH serves as a major referral tertiary centre for all parts of Kwara and the neighbouring states of Niger and Kogi, and parts of Oyo, Osun and Ekiti states of Nigeria. The Obstetric unit is housed in a two storey building and consists of a thirty (30) bed antenatal ward and a thirty bed postnatal medical ward on the second floor. The first floor houses a twenty five (25) bed postnatal surgical ward, the antenatal clinic, ultrasound unit, Family Planning Clinic, delivery suite, obstetric theatres and neonatal intensive care unit. On the ground floor is the obstetric emergency ward which also doubles as the gynaecological emergency ward.

Obstetric patients are seen in the antenatal clinic Monday to Friday. Antenatal clinics are run by four firms; each clinic is overseen by consultants, resident doctors and house officers in conjunction with midwives. Booking clinic is run every Monday on a rotational basis by the different firms. The labour ward is run by a team of doctors comprising consultants, senior registrars, registrars and interns as well as midwives; the same arrangement is made for the emergency ward. Patients planned for IOL are admitted into the antenatal ward via the antenatal clinics, emergency ward and occasionally via the labour ward.

There are about 2,000 deliveries per year in UITH. There are no published local studies on the rate of IOL or rate of failed induction. However, failed induction accounted for 10.7% of caesarean sections in a previous study25.

5.2 Study Population

Subjects were consenting pregnant women admitted for induction of labour with misoprostol at 37 weeks gestation and above.

Inclusion criteria

1. Singleton pregnancy at term and beyond

2. No evidence of onset of spontaneous labour

3. Live fetus

4. Cephalic presentation

5. Intact membranes with no history suggestive of liquor drainage

Exclusion criteria

1. Any contraindication to vaginal delivery

2. Previous uterine scar

3. Ruptured membranes

4. Multiple pregnancy

5. Gross fetal congenital anomaly

6. Cervical incompetence

7. Cervical ripening with intra-cervical Foleys catheter or other methods of IOL

8. Unsure date with no early USS scan

5.3 Study Design

This was a prospective comparative study. Homogenous purposive sampling was done. It is a non-probability sampling technique in which a group of subjects with similar characteristics

(in this case, pregnant women at term and beyond admitted for IOL who meet the selection criteria enumerated below) are recruited. This method of sampling was utilized since the research question addresses a particular group of interest. All patients admitted for induction of labour with misoprostol who met the selection criteria and consented to the study were

recruited until the minimum sample size was complete. They were counseled about the study and consent taken before proceeding.

5.4 Sample Size Determination

I compared the accuracy of sonographic cervical length with that of Bishop score in predicting successful induction of labour. The following hypotheses were considered:

H0: Both transvaginal sonographic cervical length and bishop score have the same accuracy.

H1: The accuracy is not equal between the transvaginal sonographic cervical length and bishop score.

Mathematically, this can be represented as

H0:푝1 = 푝2

H1:푝1 < 푝2

H0:푝1 = 푝2

H1:푝1 > 푝2

Sample size was determined using the formula for sample size determination when comparing sensitivities and specificities64, 65.

2 2 푍1−훼√ 휓 + 푍1−훽√ 휓 − (훿) 푛 = ( ) 훿

퐷푖푠푐표푟푑푎푛푐푒 표푟 퐷푖푠푎푔푟푒푒푚푒푛푡 = 퐷푖푓푓푒푟푒푛푐푒 = 휓 = 훿 = 푝1 − 푝2

Sensitivities for both transvaginal sonographic cervical length and Bishop’s score were

20 estimated to be 80% (푝1 = 0.8) and 64% (푝2 = 0.64) respectively in the study by Tan .

푝1 − 푝2 = 0.16

Power analysis: α of 0.05 (5% level of significance) and a β of 0.10 (power = 90%)

푍1−훼 = 푍0.95 = 1.645

푍1−훽 = 푍0.90 = 1.28

2 1.645√0.16 + 1.28√0.16 − (0.16)2 푛 = ( ) 0.16

푛 = 118.74

In order to achieve 90% power, about 119 patients would be needed for the study. To provide for attrition, 20% of sample size was added that is, 12. Thus minimum sample size was 131 subjects.

5.5 Patient Recruitment

One hundred and forty (140) subjects were enrolled. They were counseled on the nature and purpose of the study, the potential benefits and risks of participation. Consenting women were given the information sheet to read through (Appendix I) and written consent was obtained (Appendix 2). Patients were recruited by the researcher and research assistants.

5.6 Procedure

Research Instrument

A study proforma was used for data collection (Appendix III). It contained five subsections including socio-demographic characteristics, past obstetric history, pre-induction assessment, induction and neonatal outcomes. It was interviewer-administered and semi-structured with both open and close ended questions. The researcher and research assistants administered the

proforma. A pilot study was done on 13 consenting subjects (10% of the calculated sample size) to pretest the proforma and evaluate feasibility before conducting the actual research.

Necessary modifications were made. The result of the pilot study was not included in the final research.

The socio-demographic characteristics obtained included age, parity, booking status, patient’s occupation and educational status, husband’s occupation and educational status, gestational age as calculated from the LMP or early USS. Those who were unsure of date and did not have an early scan (in the first half of pregnancy) were excluded from the study. Clinical examination was carried out to validate some of the inclusion and exclusion criteria. The patient’s height and weight were measured and the Body Mass Index (BMI) calculated.

Obstetric examination was done to determine the fetal lie, presentation and viability. The transabdominal ultrasound scan done on admission was reviewed to confirm the number of fetuses, lie, presentation and viability, amniotic fluid index, estimated fetal weight, placental localization, estimate gestational age and rule out other exclusion criteria.

Measurement of Cervical Length

The measurement of cervical length was done by the researcher under the supervision of a

Consultant Radiologist who is one of the supervisors of this project. The researcher has also undergone an online training on cervical assessment by The Fetal Medicine Foundation. She also had hands-on training on cervical length measurement by the Consultant Radiologist.

Results were validated by periodic re-evaluation of the researcher by the Consultant

Radiologist. TVS was performed in the USS unit of the Obstetrics and Gynaecology

Department. A transvaginal 5MHz transducer on Aloka SSD-1000 ultrasound machine designed by ALOKA GmbH, Meerbusch, Germany was used to measure the cervical length.

The measurement was done within the hour prior to commencement of the IOL process just before assessment of the Bishop score. For each subject the following steps were carried out.

After obtaining consent, the participant was asked to empty her bladder and was placed in the dorsal position on the couch. An improvised waist wedge using a pillow was placed underneath her waist and a draw sheet over her waist, thighs and legs to maintain some privacy. The examiner then donned latex gloves. The transvaginal probe was lubricated with sterile coupling gel and covered with a latex condom. The condom-covered probe was again lubricated. The lower edge of the draw sheet was lifted and the probe gently inserted into the anterior fornix of the vagina to obtain a sagittal view of the cervix with its centrally located endocervical mucosa. The endocervical mucosa is hypoechoic compared to the surrounding cervical stroma and there is usually a thin line of demarcation between it and the latter. The internal os was identified at the proximal end of the central endocervical mucosal stripe. The external os was identiﬁed as the point at which the anterior and posterior lips of the cervix come together within the relatively hypoechoic vagina. The picture was magnified so that the cervix occupied at least 50 - 75% of the image before measurement. The length of the canal was measured as the distance between the calipers placed on the internal and external os as seen in the picture below. Where there was funnelling, the calliper for the internal os was placed at the apex of the funnel. Three measurements were taken and the shortest measurement of the cervical length was recorded on the proforma 21, 66 – 69. After each examination, the used condom was discarded, the probe was wiped clean with tissue and used gloves were discarded. Handwashing was done in between scans and a fresh condom and fresh gloves were used for each patient.

Following sonography, the patient was asked about her perception of pain on a pain numerical rating scale from 0 to 10. Point 0 represented no pain while point 10 represented unbearable pain (Appendix V) 70. The pain score was noted on the data collection sheet.

Elective inductions with misoprostol are usually commenced at 6pm in our centre but may be earlier in emergency situations.

Assessment of Bishop Score

Immediately after the TVS, a digital vaginal examination was done to assess the favourability of the cervix using the Bishop score. This was performed by the researcher so as to minimize inter-observer error and improve validity. The patient was placed in the dorsal position and the vulva swabbed with antiseptic solution. The examiner donned sterile gloves and introduced the middle and index fingers of the right hand into the vagina. The cervix was identified and assessed for the 5 parameters that make up the Bishop score. These are cervical dilatation, length and position, consistency of the cervix and station of the presenting part.

Cervical dilatation, length and station of the presenting part were scored on a scale of 0 to 3 while cervical position and consistency of the cervix were on a scale of 0 to 2 as depicted in

Appendix IV. The pain score was again determined as earlier described. The patient was asked what her choice would be if she had the opportunity of choosing between digital and

sonographic examinations and her reasons for choosing her answer. She was subsequently transferred to the antenatal ward.

Subsequent management of the patient was carried out by the obstetricians on duty according to the departmental protocol. The steps are outlined below.

Induction of Labour

Cervical ripening and induction of labour was carried out using 25ug misoprostol tablets placed in the posterior fornix of the vagina 4 hourly to a maximum of 6 doses. The patient was monitored hourly for uterine activity and fetal heart rate and four hourly for cervical changes. Misoprostol was discontinued when the patient was in active phase or when a maximum of 6 doses had been used. It was also discontinued in three patients when fetal heart rate abnormalities ensued. The patient was transferred to the labour ward in the active phase of labour. In this study, active phase of labour was defined as cervical dilatation of ≥

4cm irrespective of parity. Those with an unripe cervix following the maximum number of doses of misoprostol were diagnosed as having failed IOL; further management was determined by the managing obstetrician.

Where required, labour was augmented with oxytocin infusion. It was administered intravenously using a fluid giving set. The initial base mixture concentration was 10mIU/ml with a starting dose of 5mIU/min; the dose was increased at intervals of 30 minutes.

Maximum oxytocin flow rate was 30 mIU/min. The oxytocin end point was 3 to 5 uterine contractions in 10 minutes lasting at least 40s. Oxytocin infusion was administered for a maximum of 12 hours.

Fetal heart rate was monitored using intermittent auscultation or electrocardiotocography during the induction process. The induction outcomes were recorded in the study proforma by

the researcher and research assistants. Neonates were followed up to the first seven days of life to determine perinatal outcomes.

Research Assistants

Four research assistants (Registrar I), one from each firm, were involved in the execution of the study. They were trained on the methodology of the study and took part in the pilot study which lasted 10 days. They were involved in patient recruitment, counseling and administering the questionnaire. They also took part in recording induction outcomes following delivery.

Successful Induction of Labour

Successful induction of labour was defined as vaginal delivery within 24 hours of onset of misoprostol administration47.

Failed Induction of Labour

This was defined as failure to deliver vaginally within 24 hours of onset of induction or caesarean delivery47.

Induction-Delivery Interval

The time interval between passage of the first dose of misoprostol and delivery of the fetus.

5.7 Outcome Measures

The primary outcome measures were vaginal birth within 24 hours, failure of vaginal delivery within 24 hours, caesarean delivery, induction-delivery interval and pain scores. Secondary outcome measures were need for oxytocin augmentation, fetal heart rate abnormalities, meconium staining, Apgar scores at 1 and 5 minutes, Neonatal Intensive Care Unit (NICU) admission and perinatal mortality.

5.8 Data Analysis

All patient information was recorded on the proforma. Data collected was analysed using

Statistical Package for Social Science (SPSS) software (version 21.0; Chicago, Illinois,

USA). Descriptive statistics were expressed as median, means with standard deviation and ranges for continous variables and as percentages and frequencies for categorical variables.

The t-test was used to analyze the difference between means while Chi- square was used to analyze the relationship between categorical variables. Pearson’s correlation was done to test for linear relationship between variables. Receiver operating characteristics (ROC) curves were generated to determine the best cut-off points of Bishop score and sonographic cervical length for predicting successful labour induction. The areas under the curve (AUC) were derived as well as the sensitivity, specificity and predictive values. Multivariate regression analysis was done to investigate the effect of different variables on independent prediction of successful labour induction. P-value < 0.05 was taken as signiﬁcant.

5.9 Strengths

1. Unlike other studies where heterogeneous methods of labour induction were used; this

study was carried out on patients undergoing IOL with misoprostol. This eliminated

potential bias on induction outcome from the combination of different methods of

induction used in other studies.

2. The Bishop score assessment of all subjects was performed by the researcher alone

thus eliminating potentially significant inter-observer variation.

3. This study compared pain and discomfort felt during digital and sonographic cervical

assessment. Not many studies have done this. In addition, acceptability of both

methods was compared. The findings can be used to counsel patients undergoing TVS

in future for either obstetric or gynaecologic indications.

4. Successful induction of labour was defined as vaginal delivery in 24 hours in this

study. Though not universally accepted, this definition is increasingly being used in

newer studies and has been used as a primary outcome measure in a meta-analysis

comparing Bishop score with other methods of cervical assessment. This will make

for easy comparison of results with other studies.

5.10 Limitations

1. The researcher performed both digital and TVS examinations for the subjects. This

might introduce bias. However, the utmost objectivity was demonstrated.

2. This study was designed to be carried out on the “ideal” obstetric patient who fulfills

all the selection criteria. This however is not always the case in obstetric practice as

oftentimes patients who meet the exclusion criteria eg. unsure dates, pre-labour

rupture of membrane etc present for IOL. This may affect generalization of the results

obtained.

3. A randomized controlled trial would have given more strength to the study. However,

this was not done as there were too many confounders to enable matching.

Sponsorship

The research was sponsored with funds provided by the researcher in addition to a research grant by UITH. No added cost was transferred to the subjects.

Ethical Consideration

An institutional ethical approval was obtained from the Ethical Review Committee of the

University of Ilorin Teaching Hospital Ilorin before the commencement of the study. All information about the participants was kept confidential. Patients who had failed induction of labour and other complications such as fetal distress were managed by the attending obstetrician using institutional protocols.

Conflict of Interest

None

CHAPTER SIX

RESULTS

One hundred and forty (140) women were enrolled into the study from August 2016 to March

2017. Of these, seven dropped out either because caesarean section was decided on or method of labour induction changed after recruitment. The remaining 133 women had labour induction with misoprostol and the findings are as reported below.

A. Sociodemographic and Obstetric Characteristics

Table 1 shows the sociodemographic and obstetric variables of participants. The mean age was 29.48 ± 4.43 years. Eighty-seven percent of subjects were employed; trading was the most frequent occupation (44.4%). Ninety-seven percent of subjects had some degree of formal education. The predominant proportion of participants was Yoruba (85.7%).

Of the 133 subjects, 54.1% were parous while 45.9% were nulliparous. The median parity was 1 (range 0 – 4). The mean gestational age at onset of induction was 39.08 ± 1.72 weeks.

The commonest indication for induction of labour was hypertensive disorders (38.3%).

B. Cervical Assessment

Table 2 shows the findings on cervical assessment. The mean sonographic cervical length was 25.19 ± 10.09 (range = 0 – 44 mm). The difference in the mean sonographic cervical length and mean digital cervical length was statistically significant (8.42 ± 6.56 mm, p =

<0.001). The sonographic cervical length had a linear correlation with the cervical length on digital palpation (r = 0.761, p = <0.001).The best cut-off value for predicting successful labour induction was a sonographic cervical length of 24mm or less (Table 3, figure 1) or a

Bishop score of greater than 4 (Table 4, figure 1) .

Transvaginal sonographic cervical assessment was better tolerated. The mean difference in pain scores was 3.47 points and it was statistically significant. Eighty-seven subjects (65.4%)

preferred transvaginal ultrasound assessment. The major reason was because it was less painful (81.6%) while 18.4% of the subjects felt it was probably more accurate than digital assessment. Fifteen women (11.3%) subjects preferred digital cervical assessment; 60% of these women felt so because it was the traditional method they are accustomed to, while 40% felt it was less painful. Thirty-one participants (23.3%) did not have any preference for either method.

Table 5 shows that the bishop score was higher in subjects with successful induction than in those with failed induction. The sonographic cervical length was lower but this was not statistically significant.

C. Induction Outcomes

Table 5 summarises induction outcomes in the study population. Vaginal delivery occurred in

119 subjects (89.5%) while 14 subjects (10.5%) had caesarean delivery. Of the vaginal deliveries, 8 were assisted with vacuum. Indications for vacuum delivery were fetal distress

(50%) and maternal exhaustion (50%). Indications for caesarean section were failure to progress (50%), fetal distress (42.9%) and cephalopelvic disproportion (7.1%). The majority

(88.2%) of vaginal deliveries occurred within 24 hours. The proportion of subjects who had successful induction was 78.9% while 21.1% had failed induction. The mean induction- delivery interval was 15 hours 38 min, the median 12 hours 30 min (range = 4 hours 23 minutes to 94 hours 23 minutes). The induction-delivery interval (mean = 11 hours 12 minutes vs 32 hours 13 minutes, p = <0.001) and the number of doses of misoprostol used

(mean = 1.83 ± 0.84 vs 4.46 ± 1.48, p = <0.001) were lower in those who had successful induction.

There was a higher incidence of fetal heart rate abnormalities in those who had failed induction compared to those who had successful induction (21.4% vs 3.8%, p = 0.006). The

average birth weight was 3.06 ± 0.46 kg. There were 14 admissions into the Neonatal

Intensive Care Unit (NICU) accounting for 10.5% of cases. Eight (57.1%) of these were on account of perinatal asphyxia, four (28.6%) for low birth weight and two (14.3%) had neonatal sepsis. There was no perinatal mortality in this study.

D. Comparing Sonographic Cervical Length and Bishop Score as Tools for Cervical

Assessment

Tables 6 - 9 and figure 1 demonstrate the performance of sonographic cervical length and bishop score in predicting induction outcomes. The Bishop score had a weak inverse relationship with induction-delivery interval (r = -0.267) and the number of doses of misoprostol used (r = -0.338). Sonographic cervical length did not have a significant linear correlation with successful labour induction, induction delivery interval, the number of doses of misoprostol used and Apgar scores.

Multiple regression analysis showed that Bishop score, parity and birth weight significantly and independently predicted successful labour induction. Comparing the ROC curves generated for both tests, the AUC curve for Bishop score was higher than that of sonographic cervical length (0.6617 compared to 0.6199). Using the best cut-off points previously derived from the ROC curves, sonographic cervical length had a higher sensitivity (52.4% versus

47.6%) and a lower specificity (78.6% versus 82.1%) than the Bishop score.

Table 8 demonstrates the performance of sonographic cervical length ≤24 mm and Bishop score >4 in predicting induction outcomes. At these thresholds, there was a 90% chance of achieving vaginal delivery, the induction-delivery interval was lower and lower doses of misoprostol were administered. Also, at a Bishop score >4, there was less need for oxytocin augmentation and more NICU admissions.

Table 1: Sociodemographic and obstetric variables of the study population

Variables Frequency Percent Age group (years) 21 – 25 25 18.8 26 – 30 64 48.1 31 – 35 32 24.1 36 - 40 12 9.0 Mean ± SD 29.48 ± 4.43 Marital status Married 133 100 Occupation Unemployed 17 12.8 Artisan 20 15 Trading 59 44.4 Civil servant 29 21.8 Professional 8 6 Educational status None 4 3 Primary 3 2.3 Secondary 40 30.1 Tertiary 86 64.6 Ethnicity Yoruba 114 85.7 Igbo 13 9.8 Hausa 2 1.5 Others 4 3 Parity Nulliparous 61 45.9 Primiparous 32 24.1 Multiparous 40 30

Table 1 (Continued): Sociodemographic and Obstetric Variables of the study population

Variables Frequency Percent

Previous history of prolonged pregnancy (n = 72) Yes 13 18.1 No 59 81.9 Previous history of prolonged labour (n = 72) Yes 7 9.7 No 65 90.3 Previous history of induced labour (n = 72) Yes 16 22.2 No 56 77.8 Indications for IOL in index pregnancy IUGR 2 1.5 SCD with recurrent VOC at term 2 1.5 Previous IUFD at term 3 2.3 Reduced fetal movements 3 2.3 Prolonged pregnancy 8 6 Oligohydramnios 16 12 Post-datism 48 36.1 Hypertensive disorder 51 38.3

Table 2: Cervical assessment in the study population

Variable Range Mean ± SD Median t p value

Bishop score 0 – 7 3.71± 1.98 4

Cervical length measurement (mm)

Sonographic cervical length (mm) 10 – 44 25.19 ± 10.09 27 14.976 <0.001*

Digital examination (mm) 10 -30 16.77 ± 8.10 20

Assessment of Pain from procedure

Sonographic pain score 0 – 6 0.95 ± 1.40 0 -19.184 <0.001*

Bishop pain score 0 – 10 4.42 ± 2.37 4 t: Independent sample T tests; *: p value <0.05

Figure 1: ROC Curves of Sonographic cervical length and Bishop score in predicting successful induction

Area under the curve (sonographic cervical length): 0.619898; p value: 0.059; 95%

Confidence interval: 0.5317 to 0.7026

Area under the curve (Bishop score): 0.6617; p value: 0.0046; 95% Confidence interval:

0.5746 to 0.7415

Table 3: Sensitivity and Specificity for Sonographic cervical length in predicting successful induction in the study population (Criterion values and coordinates of the

ROC curve)

Criterion Sensitivity 95% CI Specificity 95% CI

≤ 0 3.81 1.0 - 9.5 85.71 67.3 - 96.0

≤ 20 27.62 19.3 - 37.2 85.71 67.3 - 96.0

≤ 21.3 27.62 19.3 - 37.2 78.57 59.0 - 91.7

≤ 24 52.38 42.4 - 62.2 78.57 59.0 - 91.7

≤ 26 52.38 42.4 - 62.2 67.86 47.6 - 84.1

≤ 28 62.86 52.9 - 72.1 67.86 47.6 - 84.1

≤ 29 66.67 56.8 - 75.6 57.14 37.2 - 75.5

Youden index (J): 0.3095; associated criterion: ≤ 24

Table 4: Sensitivity and Specificity for Bishop score in predicting outcome of induction of labour in the study population (Criterion values and coordinates of the ROC curve)

Criterion Sensitivity 95% CI Specificity 95% CI

> 1 86.67 78.6 - 92.5 32.14 15.9 - 52.4

> 2 76.19 66.9 - 84.0 46.43 27.5 - 66.1

> 3 60.95 50.9 - 70.3 57.14 37.2 - 75.5

> 4 47.62 37.8 - 57.6 82.14 63.1 - 93.9

> 5 22.86 15.2 - 32.1 92.86 76.5 - 99.1

> 6 5.71 2.1 - 12.0 92.86 76.5 - 99.1

> 7 0.00 0.0 - 3.5 100.00 87.7 - 100.0

Youden index (J): 0.2976; associated criterion: >4

Table 5: The relationship between cervical parameters and some outcome measures with successful and failed induction in the study population Outcome of induction Successful Failed Total χ2 or t p value Variable n = 105 (%) n =28 (%) N = 133 (%) Sonographic cervical length (mm) Mean ± SD 24.76±9.55 26.77±11.97 -0.936 0.351 Bishop score Mean ± SD 3.93±1.93 2.86±1.98 2.611 0.010* Cervical length on digital palpation Mean ± SD 16.31±8.14 18.46±7.85 -1.251 0.213 Induction delivery interval ≤12 58 (55.2) 3 (10.7) 61 (45.9) 88.647 <0.001* >12 - ≤24 47 (44.8) 5 (17.9) 52 (39.1) >24 0 (0.0) 20 (71.4) 20 (15.0) Mean ± SD 11:12 ± 4:44 32:13 ± -9.952 <0.001* 19:47 Number of doses of Misoprostol used Mean ± SD 1.83 ± 0.84 4.46 ± 1.48 - <0.001* 12.351 1st minute Apgar score < 7 31 (29.5) 5 (17.9) 36 (27.1) 1.524 0.217 ≥ 7 74 (70.5) 23 (82.1) 97 (72.9) Mean ± SD 6.87 ± 1.57 7.00 ± 4.67 -0.405 0.686 5th minute Apgar score < 7 12 (11.4) 0 (0.0) 12 (9.0) 2.263Y 0.132 ≥ 7 93 (88.6) 28 (100.0) 121 (91.0) Mean ± SD 8.48 ± 1.47 8.75 ± 0.70 -0.956 0.341 Oxytocin augmentation Yes 37 (35.2) 13 (46.4) 50 (37.6) 1.180 0.277 No 68 (64.8) 15 (53.6) 83 (62.4) Meconium Staining No 78 (74.3) 20 (71.4) 98 (73.7) 1.298Y 0.730 Yes 27 (25.7) 8 (28.6) 35 (26.3) Birth weight Mean ± SD 3.121 ± 2.828 ± 3.127 0.002* 0.441 0.439 Fetal heart rate abnormalities Yes 4 (3.8) 6 (21.4) 10 (7.5) 7.497Y 0.006* No 101 (96.2) 22 (78.6) 123 (92.5) Need for NICU admission Yes 11 (10.5) 3 (10.7) 14 (10.5) 0.096Y 0.757 No 94 (89.5) 25 (89.3) 119 (89.5)

χ2: Chi square test; Y: Yates corrected Chi square; t: Independent Samples T test; *: p value <0.05

Table 6: Linear correlation of cervical assessment methods with some outcomes

Sonographic cervical length Bishop score

Variables R p value r p value

Induction-delivery interval 0.130 0.137 -0.267 0.002*

Number of doses used 0.114 0.192 -0.338 < 0.001*

Apgar score at 1 minute 0.059 0.498 0.077 0.381

Apgar score at 5 minutes 0.135 0.123 0.162 0.063 r: Pearson correlation coefficient; *: statistically significant (i.e. p value < 0.05)

Table 7: Regression analysis of predictors of successful labour induction

Univariate analysis Multivariate analysis

Variable B p value OR (95% CI) B p value OR (95% CI)

Birth weight 1.677 0.003* 5.350(1.748–16.372) 1.531 0.019* 4.624(1.289–16.587)

Parity 1.525 < 0.001* 4.596(2.074–10.182) 1.447 < 0.001* 4.250(1.935–9.336)

Previous -18.331 0.999 0.000(0.000- NA induction Bishop score 0.279 0.012* 1.321(1.062–1.643) 0.312 0.017* 1.366(1.056–1.767)

Sonographic -0.021 0.349 0.979(0.937–1.023) NA cervical length BMI 0.041 0.322 1.042(0.960–1.131) NA

Gestational 0.097 0.435 1.102(0.863–1.408) NA age B: regression coefficient; OR: odds ratio; CI: confidence interval; *: statistically significant (i.e. p value < 0.05)

Table 8: Comparison of sonographic cervical length and Bishop score with outcome measures

Sonographic cervical length ≤ 24mm > 24mm Total χ2 or t p value Variable n (%) n (%) n (%) Overall Outcome Successful induction 55 (90.2) 50 (69.4) 105 (78.9) 8.530 0.003* Failed induction 6 (9.8) 22 (30.6) 28 (21.1) Oxytocin augmentation Yes 18 (29.5) 32 (44.4) 50 (37.6) 3.140 0.076 No 43 (70.5) 40 (55.6) 83 (62.4) Fetal heart rate abnormality Yes 2 (3.3) 8 (11.1) 10 (7.5) 1.896Y 0.169 No 59 (96.7) 64 (88.9) 123 (92.5) Meconium staining No 47 (77.0) 51 (70.9) 98 (73.7) 1.586Y 0.663 Yes 14(23.0) 21 (29.1) 35 (26.3) NICU admission Yes 7 (11.5) 7 (9.7) 14 (10.5) 0.108 0.743 No 54 (88.5) 65 (90.3) 119 (89.5) Number of doses of Misoprostol used Mean ± SD 1.85 ± 0.963 2.83 ± 1.67 -4.051t <0.001* 1st minute Apgar score < 7 16 (26.2) 20 (27.8) 36 (27.1) 0.040 0.841 ≥ 7 45 (73.8) 52 (72.2) 97 (72.9) Mean ± SD 6.87 ± 1.77 6.92 ± 1.34 -0.177 t 0.860 5th minute Apgar score < 7 8 (13.1) 4 (5.6) 12 (9.0) 2.299 0.129 ≥ 7 53 (86.9) 68 (94.4) 121 (91.0) Mean ± SD 8.34 ± 1.53 8.69 ± 1.16 -1.502 t 0.135 Induction delivery interval ≤12 39 (63.9) 22 (30.6) 61 (45.9) 16.061 <0.001* >12 - ≤24 18 (29.5) 34 (47.2) 52 (39.1) >24 4 (6.6) 16 (22.2) 20 (15.0) Mean ± SD 11:03 ± 5:56 19:30 ± 16:00 -3.900 t <0.001*

χ2: Chi square test; Y: Yates corrected Chi square; t: Independent Samples T test; *: p value <0.05

Table 8 (Cont): Comparison of sonographic cervical length and Bishop score with outcome measures

Bishop Score > 4 ≤ 4 Total χ2 or t p value Variable n (%) n (%) n (%) Overall outcome Successful induction 50 (90.9) 55 (70.5) 105 (78.9) 8.074 0.004* Failed induction 5 (9.1) 23 (29.5) 28 (21.1) Oxytocin augmentation Yes 15 (27.3) 35 (44.9) 50 (37.6) 4.258 0.039* No 40 (72.7) 43 (55.1) 83 (62.4) Fetal heart rate abnormality Yes 3 (5.5) 7 (9.0) 10 (7.5) 0.180Y 0.671 No 52 (94.5) 71 (91.0) 123 (92.5) Meconium staining No 42 (76.4) 56 (71.7) 98 (73.7) 1.223Y 0.747 Yes 13 (23.6) 22 (28.2) 35 (26.3) NICU admission Yes 10 (18.2) 4 (5.1) 14 (10.5) 5.836 0.016* No 45 (81.8) 74 (94.9) 119 (89.5) Number of doses of Misoprostol used Mean ± SD 1.96 ± 0.77 2.68 ± 1.75 -2.838 t 0.005* 1st minute Apgar score < 7 18 (32.7) 18 (23.1) 36 (27.1) 1.522 0.217 ≥ 7 37 (67.3) 60 (76.9) 97 (72.9) Mean ± SD 6.75 ± 1.87 7.00 ± 1.27 -0.936 t 0.351 5th minute Apgar score < 7 8 (14.5) 4 (5.1) 12 (9.0) 2.432Y 0.119 ≥ 7 47 (85.5) 74 (94.9) 121(91.0) Mean ± SD 8.47 ± 1.63 8.58 ± 1.11 -0.936 t 0.351 Induction-delivery interval ≤12 31 (56.4) 30 (38.5) 61 (45.9) 16.851 <0.001* >12 - ≤24 24 (43.6) 28 (35.9) 52 (39.1) >24 0 (0.0) 20 (25.6) 20 (15.0) Mean ± SD 11:40 ± 4:29 18:25±16:09 -3.014 t 0.003* χ2: Chi square test; Y: Yates corrected Chi square; t: Independent Samples T test; *: p value <0.05

Table 9: Comparing the sensitivity, specificity, positive predictive value, negative predictive value, false positive and negative rates of the optimum sonographic cervical length and Bishop Score

Evaluation Sonographic cervical length Bishop score (>4)

(≤24mm)

Sensitivity 52.4% 47.6%

Specificity 78.6% 82.1%

Positive Predictive Value 90.2% 90.9%

Negative Predictive Value 30.6% 29.5%

False Positive 21.4% 17.9%

False Negative 47.6% 52.4%

CHAPTER SEVEN

DISCUSSION, CONCLUSIONS AND RECOMMENDATIONS

7.1 Discussion

In this study, the sonographic cervical length ranged between 0 – 44 mm. The mean sonographic and median sonographic cervical lengths were 25.19 and 27mm respectively.

Other studies have reported mean cervical lengths ranging from 18 mm – 30mm2, 7, 19, 54. The high figure (30mm) reported by Gonen et al54 may be attributable to the inclusion of preterm subjects in the study. Pandis et al reported a median sonographic cervical length of 25mm15 which is comparable to that reported in this study. Lower figures (18 mm in nulliparae and 16 mm in women with previous deliveries) were reported by Rane et al in a study of pregnancies

>41 weeks gestation 73. The gestational age at induction could have accounted for this difference. There was a strong linear relationship between the cervical length on transvaginal sonographic and digital examinations (r = 0.761, p = <0.001). Sonek et al also reported a linear relationship between both variables but the correlation coefficient was smaller (0.49)21.

In this study, the cervical length on digital palpation was significantly lower than the transvaginal sonographic cervical length (mean difference = 8.42 ± 6.56 mm, p = <0.001).

This was similar to the findings by Daskalakis et al and Johnson et al71, 72. This may be because definite landmarks are used for TVS measurement of the cervix which can be objectively assessed even when the cervix is closed while digital cervical examination is more subjective.

The definitions of successful and failed induction of labour varies in different studies. This makes comparison of results difficult. This study defined successful induction as vaginal delivery within 24 hours of onset of induction. This was the same definition used in the studies by Buenos et al3, Cengiz et al23, Pandis et al15, Gonen et al54 and Reis et. It has also

been used to define outcome measures in systematic reviews1, 47 and a meta-analysis in the

Cochrane database1. The rate of successful induction was 78.9% in this study. Tan et al and

Rane et al also reported high success rates of 77.9%20 and 70%73 respectively. However, the definition of successful IOL in the study by Tan et al was vaginal delivery irrespective of duration of labour. This most likely contributed to the high success rate in the study.

Buenos et al and Pandis et al had lower success rates of approximately 60%3, 15. This may be because of the lower proportion of parous women in their studies. In contrast, 54.1% of subjects in the present study had previous delivery. This and other studies with high success rates have shown that parity is a significant predictor of induction success3, 24, 54, 73. In addition, patients in this study had misoprostol while the other two studies made use of dinoprostone gel, amniotomy alone or amniotomy with oxytocin infusion. This may have contributed to the different success rates reported.

The optimum cut-off values for predicting successful induction of labour were a sonographic cervical length ≤24 mm and a Bishop score >4. This is comparable with those reported in the studies by Pandis et al, Gonen et al and Tan et al which were 28mm and 315, 27mm and >554,

<20mm and ≥520 respectively. In the same vein, Rane et al also obtained optimum cut-off sonographic cervical length of 24mm73 while Bahadori et al and Park reported 22cm2 and

28mm5 respectively. These studies were in consonance with the index study although they did not demonstrate the cut-off Bishop score for predicting successful labour induction.

However, Cengiz et al reported a cut-off Bishop score of ≥223 which is lower than the score of >4 in this study.

This study showed that Bishop score, parity and birth weight were independent predictors of successful labour induction. However, sonographic cervical length did not significantly predict successful induction of labour. Similarly, Reis et al24 and Gonen et al54 found that

Bishop score and parity, but not sonographic cervical length were independent predictors of successful labour induction on multivariate analysis. In a study of pregnancies > 41 weeks,

Chandra et al found that digital cervical palpation and parity independently predicted any vaginal delivery; however only parity predicted vaginal delivery within 24 hours22.

As in the present study, Cengiz et al used a single induction agent on all subjects23; hence both studies are comparable as the confounding effect of different inducing agents was absent. It is therefore not surprising that both studies did not did not find any significant association between sonographic cervical length measurement and successful labour induction. Both demonstrated that the Bishop score could independently predict successful induction of labour. Bishop score is a sum of factors which include cervical length and is therefore likely to be a stronger correlate for successful induction of labour.

Other studies found that both sonographic cervical length and Bishop score independently predict vaginal delivery within 24 hours 3, 15, 73 though sonographic cervical length was a better predictor. Pandis et al further demonstrated that of all the components of the Bishop score, only cervical length significantly contributed to predicting vaginal delivery within 24 hours. Reis et al on the other hand, found that cervical dilatation and effacement are the only two components of the Bishop score that significantly affect induction outcomes24.

In this study, the Bishop score showed linear correlation with induction-delivery interval (r =

-0.267, p = 0.002). Gonen et al and Bastani et al reported that both Bishop score and sonographic cervical length had a linear correlation with success of labour induction and induction-delivery interval54.

The ROC curves in this study demonstrated better performance of the Bishop score in predicting successful induction than the sonographic cervical length. The AUC of the Bishop score and sonographic cervical length in this study are comparable to findings in other

studies5, 20, 23. The AUC for Bishop score in this study was higher than that of sonographic cervical length (0.6617 vs 0.6199). In addition, that of sonographic cervical length was not statistically significant (p = 0.059). This was consistent with the findings by Cengiz et al. In contrast, Tan et al found that the sonographic cervical length had a better performance (0.611 vs 0.607)20. Rane et al also reported better performance of sonographic cervical length (0.82 vs 0.72)73; both tests had high AUCs compared to those observed in the index and previously quoted studies20, 23. The subjects had shorter cervices (median = 18mm vs 27mm in present study) and probably higher Bishop scores due to the effect of prolonged pregnancy. However, the index and other studies3, 24 have failed to prove a significant association between gestational age and success of labour induction on logistic regression.

Comparing the sensitivity, specificity, positive and negative predictive values of sonographic cervical length and Bishop score obtained with those in other studies is challenging as different studies used different values in their analysis. Using the optimum cut-off values of sonographic cervical length and Bishop score (24mm and 4), sonographic cervical length had a higher sensitivity (52.4% vs 47.6%) and negative predictive value (30.6 vs 29.5%). The

Bishop score had a higher specificity (82.1% vs 78.6%) and positive predictive value (90.9% vs 90.2%). The sensitivity of Bishop score >4 in determining successful labour induction was

47.6% in this study. This compares with the findings of a systematic review of the predictive performance of Bishop score on induction success60. Rane et al had a similar cut-off sonographic cervical length (24mm) as this study73. However the sensitivity was much higher than that derived in this study (84% vs 47.6%) and specificity was lower (59% vs 82.1%)73.

This study has shown that women undergoing IOL with misoprostol who have a Bishop score

>4 or a sonographic cervical length ≤ 24mm have about 90% chance of achieving successful vaginal delivery within 24 hours. This information can be used when counseling patients for

labour induction. Also in patients who have non-emergent indications for labour induction, the induction process may be delayed till the optimum cervical parameters are attained as long as there is no risk to the mother and fetus. This will ensure that induction is done at such a time that it is likely to succeed.

Transvaginal ultrasonography for sonographic cervical length measurement was better tolerated than digital assessment for Bishop score (mean score on VAS 0.95 ± 1.40 vs 4.42 ±

2.37). The difference in the mean scores was 3.47 and this was statistically significant. This confirms the findings in other studies20, 22. TVS assesses only one parameter and does not require manipulation of the cervix. Bishop score assessment on the other hand assesses five parameters and requires manipulation of the cervix; this may contribute to more discomfort.

This study went a step further to assess the acceptability of both tests. Given a choice, majority of the subjects (65.4%) preferred TVS over digital examination, 11.3% preferred digital examination while 23.3% were indifferent. Despite the higher pain scores they reported, 9 of the 15 women who preferred Bishop score did so because they felt it was ‘more natural/traditional’ and they had more experience with it.

7.2 Conclusions

In women undergoing induction of labour at term and beyond with misoprostol, the optimum cut-off point of sonographic cervical length and Bishop score in predicting successful labour induction are ≤24mm and >4 respectively. Bishop score and parity significantly, unlike sonographic cervical length, can independently predict vaginal delivery within 24 hours and the induction-delivery interval. The Bishop score is more accurate than sonographic cervical length in predicting outcome of labour induction. Transvaginal sonographic cervical assessment is less painful and more acceptable to subjects than digital cervical assessment.

7.3 Recommendations

1. The Bishop score should not be replaced with sonographic cervical length

measurement in women undergoing induction of labour with misoprostol as it has

better superiority in predicting induction outcomes.

2. Women undergoing induction of labour with misoprostol at term and beyond can be

counseled that they have a 90% chance of successful induction when they have a

Bishop score of greater than 4 or a sonographic cervical length ≤ 24mm.

3. Induction of labour can be delayed till the optimum cervical parameters are attained

in selected patients as long as there is no identifiable risk to the mother and fetus. This

will ensure that induction is done at such a time that it is likely to succeed.

4. Obstetric patients undergoing transvaginal ultrasonography can be reassured that it is

a tolerable procedure.

5. More randomised controlled trials need to be done to compare the predictive value of

bishop score with those of other methods.

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APPENDIX I: INFORMATION SHEET FOR PROSPECTIVE PARTICIPANTS.

STUDY TITLE: PREDICTING OUTCOME OF LABOUR INDUCTION USING

SONOGRAPHIC CERVICAL LENGTH AND BISHOP SCORE AT UNIVERSITY

OF ILORIN TEACHING HOSPITAL

Brief Description of the Study

Induction of labour is commencement of labour with artificial agents without waiting for its natural onset. It is an important procedure for your health and that of your baby as it helps to deliver your baby at the optimal time to avoid complications of pregnancy. It may however fail if proper assessment is not done before starting. In this study, a vaginal examination will be performed to calculate your Bishop score which is the traditional method of assessing the cervix for the likelihood of success of induction. A transvaginal ultrasound will also be done to assess your cervix and both methods will be compared to determine which is more effective.

Benefits of Participation

Your consultant and other doctors managing your pregnancy have concluded that you will benefit from induction of labour and that explains why you have been selected for this study.

Participation in this study will assist us in counseling you better on the possible outcomes of the induction procedure. It will also contribute to general knowledge and improved management of pregnant women undergoing induction of labour. The cost of the transvaginal ultrasound will be borne by me.

Confidentiality

The information provided will be treated with the strictest confidentiality.

What is expected of you as you Participate?

Aside from the usual steps taken in this facility for women undergoing induction of labour, you would be required to answer some questions and a transvaginal ultrasound examination to measure your cervical length prior to the onset of induction. The duration of the interview and the examination would take about 30 minutes of your time. The outcome of the induction process will be recorded and analysed. You may also have more abdominal and vaginal examinations than routinely done during the procedure.

Risk of Participation

The procedure is generally safe with minimal discomfort to the patient. There is no additional risk due to your participation.

Your Participation is Voluntary

Your participation is voluntary and you may withdraw from the study at any time if you so desire. Please note that your participation or refusal to participate will in no way influence the quality of care offered to you. I would be very grateful if you give consent for full participation.

Thank you.

RESEARCHER: DR RAJI S. T. (MBBS)

ADDRESS: DEPARTMENT OF OBSTETRICS & GYNAECOLOGY, UITH

TELEPHONE NO: 08062392391

EMAIL: [email protected]

APPENDIX II: CONSENT FORM

STUDY TITLE: COMPARISM OF SONOGRAPHIC CERVICAL LENGTH AND

BISHOP SCORE IN PREDICTING OUTCOME OF INDUCTION OF LABOUR AT

UNIVERSITY OF ILORIN TEACHING HOSPITAL

I……………………………………………………………………..of………………………

……………………......

...... hereby consent to participate in the above research after proper information on the nature of the study and its benefit and risks have been explained to me.

Date ………………………………………………

Signed……………………………………………

Right thumb print…………………………………

I confirm that I have explained to you the purpose and nature of the study. All information obtained in this study is strictly confidential. If the study is published, there will be no information that will identify you as a participant.

Signed………………………………… Date………………………………………

Witness------

Signed------Date …………………….

APPENDIX III: STUDY PROFORMA FOR DATA COLLECTION

(a) Socio – Demographic Characteristics

Patient Initial______Hospital Number______

Address______

Phone Numbers______

Age______

Marital Status 1. (Single) 2. (Married) 3.( Divorced) 4.(Separated) 5.(Widowed)

Occupation 1. (Unemployed) 2. (Artisan) 3. (Trader) 4. (Civil Servant) 5.

(Professional) 6. Others – Specify------

Educational Status______1. (Primary) 2.( Secondary) 3.(Tertiary) 4.(Others -

Specify)

Ethnicity______{Yoruba, Igbo, Hausa, Others (specify)}

Husband’s Occupation 1. (Unemployed) 2. (Artisan) 3. (Trader) 4. (Civil

Servant) 5. (Professional) 6. Others – Specify------

Husband’s Educational Status 1. (Primary) 2.( Secondary) 3.(Tertiary) 4.(Others -

Specify)

Parity______

Last Menstrual Period_____ Expected date of delivery------

Gestational age at commencement of induction ………………...

Height______m Weight______Kg BMI______Kg/m2

(b) Past Obstetric History

I. Number of previous deliveries …(a)1 (b)2 (c)3 (d)4 (e)5 or more

II. Previous history of prolonged pregnancy Yes No

III. Previous history of prolonged labour Yes No

IV. Previous history of induced labour Yes No

V. If yes, indication………………………………………

VI. Outcome………………………………………………………………..

I. Indication for induction of labour

II. Sonographic cervical length …………… Pain Score ……………….

III. Bishop score: ……………………….. Pain Score …………………….

Parameter Score

Cosistency

Dilatation

Effacement

Position

Station

Total

IV. Cervical length on digital palpation …………………………………..

V. If you had a choice between digital and USS assessment of your cervix,

which would you choose? 1. (Digital) 2.(USS) 3. (Indifferent)

VI. Reasons for your choice (choose as many as you think right):

Less invasive of your privacy ………..

Less painful…………………….

Probably more accurate…………..

Cheaper ……………………

Others…………………………….

(d) Induction and Outcome

I. Onset of induction (Date and Time)…………………………

Misoprostol Yes No Date Time II 2nd dose III 3rd dose IV 4th dose V 5th dose VI 6th dose

VII. Number of doses……….

VIII. Oxytocin augmentation Yes No

IX. If yes, dose at adequate contractions ………

X. Date and Time of delivery ………………………………………..

XI. Fetal heart rate abnormalities Yes No

XII. If yes, type………………..

XIII. Meconium staining No Fresh Stale Blood

XIV. Mode of delivery

(a) vaginal delivery Yes No

(b) Instrumental vaginal delivery Yes No

Vacuum delivery Yes No

Forceps delivery ……………..Yes No

If yes, indication………………………

Indication………………………….

Cervical dilatation at decision

XV. Induction – Delivery Interval (hours) …………..

XVI.

(e) Neonatal Outcome

I. First minute Apgar score………………

II. Fifth minute Apgar score……………..

III. Birth weight…………………………

IV. Requirement for neonatal intensive care unit admission…Yes No

a. If yes, indication for admission…………………………..

b. Time and date of admission ………………………………..

c. Time and date of discharge/death …………………………..

d. Duration of admission…………………………… days

V. Perinatal mortality Yes No

VI. Cause of death ………………………………………………………

APPENDIX IV: BISHOP SCORE

Score 0 1 2 3

Dilatation (cm) Closed 1 – 2 3 – 4 >4

Effacement (%) 0 - 39 40 - 59 60 - 79 >/80

Consistency Firm Medium Soft -

Position Posterior Middle Anterior

Station -3 -2 -1, 0 +1, +2

APPENDIX V: PAIN NUMERICAL RATING SCALE

After Transvaginal Scan

On a scale of 0 to 10, with 0 being no pain at all and 10 being the worst pain

imaginable, how would you rate your pain right now?

0 1 2 3 4 5 6 7 8 9 10

No pain worst pain imaginable

After Pelvic Assessment for Bishop Score

On a scale of 0 to 10, with 0 being no pain at all and 10 being the worst pain

imaginable, how would you rate your pain right now?

0 1 2 3 4 5 6 7 8 9 10

No pain worst pain imaginable

APPENDIX VI: ETHICAL APPROVAL

APPENDIX VII: CERTIFICATE OF ATTENDANCE OF RESEARCH

METHODOLOGY IN MEDICINE WORKSHOP