Determination of Normative Values of Stretched Penile Length

DETERMINATION OF NORMATIVE VALUES OF STRETCHED PENILE LENGTH

AND TESTICULAR VOLUME OF APPARENTLY HEALTHY TERM IGBO

NEONATES IN ENUGU.

A DISSERTATION SUBMITTED TO NATIONAL POSTGRADUATE MEDICAL

COLLEGE OF NIGERIA IN PARTIAL FULFILMENT OF THE REQUIREMENTS

FOR THE FELLOWSHIP IN THE FACULTY OF PAEDIATRICS.

CHIKANI UGO NNENNA. MBBS (NIG), 2004.

DEPT OF PAEDIATRICS UNTH, ENUGU.

EXAMINATION DATE: MAY 2013

DECLARATION

I hereby affirm that this work is original unless otherwise acknowledged. The work has neither been presented to any other College for a Fellowship nor has it been submitted elsewhere for publication.

______

CHIKANI UGO NNENNA

DATE______

ATTESTATION

The candidate did the study reported in this dissertation under our supervision. We also supervised the writing of the dissertation.

DR IKEFUNA AN (FMCPaed) CONSULTANT PAEDIATRICIAN/LECTURER UNTH, ENUGU. SIGNATURE: ______DATE: ______

DR ADIMORA GN (FMCPaed) CONSULTANT PAEDIATRICIAN/LECTURER UNTH, ENUGU. SIGNATURE:______DATE:______

DR IBEKWE MU (FWACP) CONSULTANT PAEDIATRICIAN/LECTURER FEDERAL TEACHING HOSPITAL ABAKILIKI SIGNATUE:______DATE:______

DEDICATION

This work is dedicated to all the babies and their mothers who participated in the study and to my mother Angelina, of blessed memory, whose love for the medical profession was unparalleled.

ACKNOWLEDGEMENTS

I wish to express my profound gratitude to Almighty God and the Blessed Virgin Mary for their inspiration and guidance towards me.

I am most indebted to my supervisors; Drs Ikefuna A N, Adimorah G N and Ibekwe M for their mentorship, steadfast counsel and critical appraisal of this work.

I am most grateful to my research assistants, Drs Eze and Ugwoke for their immense help and co-operation.

I must not forget to thank Dr Chinawa C J who actually introduced me to the world of research and helped me in understanding the intrigues in research.

I wish to acknowledge Dr T Oguonu and Dr M. Ughasoro who painstakingly read the manuscript and made constructive comments in spite of short notice.

To all my teachers and colleagues in the Department of Paediatrics, UNTH, Ituku-Ozalla, Enugu, for their advice and help in the course of the work, I wish to say thank you.

I wish to thank my father, Fabian for his endless bounty of love and my siblings, for being there always.

I appreciate the efforts of my statistician Gabriel, who did the statistical aspect of my work.

Finally, My love and gratitude to the perennial keepers of my heart my husband Mark and my children, I thank you all for your understanding and support.

TABLE OF CONTENTS

Title______i

Declaration______ii

Attestation______iii

Dedication______iv

Acknowledgements______v

Table of contents______vi

List of Abbreviations______viii

List of Tables______ix

List of Figures______x

List of Appendices______xi

Summary______xii

Introduction______1

Literature Review______3

Objectives______13

Methodology______14

Results______22

Discussion______40

Conclusion______44

Recommendation______45

Limitation of study______46

Lines of Future Research______47

Reference______48

Appendices______59

LIST OF ABBREVIATIONS

BW Birth weight

BL Body Length

ESUTH Enugu State University Teaching Hospital

GA Gestational Age

MCSH Mother of Christ Specialist Hospital

SD Standard deviation

SPL Stretched Penile Length

TV Testicular Volume

UNTH University of Nigeria Teaching Hospital

LIST OF TABLES

Table No Page

Table I: Stratification of study subjects according to gestational age 16

Table II: Distribution of Birth Weight (kg) of subjects 23

Table III: Distribution of body length (cm) 24

Table IV: Distribution of Stretched penile length (cm) of subjects 25

Table V: Smoothed percentiles for stretched penile length (cm) 26

Table VI: Distribution of testicular volume (ml) of subjects 27

Table VII: Percentiles for testicular volume (ml) by gestational age (weeks) 28

Table VIII: Pearson’s correlation between stretched penile length and testicular volume with growth parameters of birth weight and length. 29

TableIX: Linear Regression for Stretched penile length versus Testicular volume 31

Table X: Linear Regression for Stretched penile length versus Body length 32

Table XI: Linear Regression for Stretched penile length versus Gestational age 33

Table XII: Multiple regression of Stretched penile length versus Gestational age and Testicular volume. 34

LIST OF FIGURES Page

Figure 1: Distribution of subjects according to gestational age (weeks). 22

Figure 2: Linear regression showing the correlation between SPL and TV 35

Figure 3: Linear Regression showing the correlation between SPL and BL 36

Figure 4: Linear Regression showing correlation between SPL and BW 37

Figure 5: Linear Regression showing correlation between SPL and GA 38

Figure 6: Linear Regression showing correlation between SPL and GA 39

LIST OF APPENDICES

Appendix Page

Appendix A: Ethical Clearance (UNTH) 5 9

Appendix B: Ethical Clearance (ESUTH) 60

Appendix C: Written Permission (MCSH) 61

Appendix D: Consent Form 62

Appendix E: Study Proforma 64

SUMMARY

Establishing the normal penile length of newborn males for every population is of paramount importance as various studies have shown disparity in penile length among different racial and ethnic groups. The reference value currently in use was derived from the Caucasoid race and may not be applicable to Afro population. In addition, the extent of in –utero development of penile length depends partly on the level of testosterone secreted by the testes, which has been found to have a direct positive correlation with testicular volume. There is also a linear relationship between stretched penile length and gestational age, especially from mid trimester until birth.

Indigenous data on the normal penile length and testicular volume of healthy Igbo neonates will help in early diagnosis and prompt treatment of anomalies of penile length and testicular volume such as micropenis and testicular agenesis.

This descriptive, cross-sectional and hospital based study was undertaken to determine the normative values of stretched penile length and testicular volume of apparently healthy term

Igbo neonates in Enugu. Eight hundred and eleven apparently healthy term male neonates within the first three days of life were studied. The stretched penile length was measured using

Schonfeld method while the testicular volume was determined with the Prader orchidometer.

The mean and standard deviation of both stretched penile length and testicular volume were calculated. In addition, the stretched penile length and testicular volume for each gestational age

(37 to 42 weeks) were determined. The relationships between penile length and testicular volume with growth parameters were determined using the Pearson’s correlation coefficient while the linear relationship between the variables were established using the linear regression analyses.

The mean stretched penile length was 3.46cm ± 0.44cm and the mean testicular volume was

1.74mls±0.62. There was a significant positive correlation between the stretched penile length and testicular volume(r =0.592, p =0.0001) as well as body length(r= 0.357, p = 0.0001) and birth weight(r = 0.224, p=0.0001) There was a significant linear relationship between stretched penile length and testicular volume(R =0.356,p=0.0001) as well as body length

(R2=0.117,p=0.0001) using linear regression analysis. Formula was derived for predicting stretched penile length using testicular volume.

The first set of standards for stretched penile length and testicular volume according to gestational age in healthy term Igbo neonates has been established and the mean stretched penile length was found to differ from those reported among other races. These determined values can be used as reference values for Igbo and Nigerian babies at large.

INTRODUCTION

Penile length in newborn males varies among different populations. This is an evidence-based statement emanating from various studies done among different racial/ethnic groups.1-11This observed difference in penile lengths is believed not only to be due to racial differences but also an interplay of some genetic and environmental factors.2 Consequent to this, several countries worldwide have aimed to establish the normative value of stretched penile length for their own populations.5-11 The normal value of penile length currently in use was derived from three widely referenced studies1,3,4 done among Caucasians and may not be applicable to all populations.

Determination of race-related standard values for penile lengths can be helpful for early diagnosis and treatment of potential disease conditions that present with micropenis, as well as to avoid over assessment of micropenis. For instance, Fok et al9 in Hong Kong found out that micropenis would have been over diagnosed in Chinese newborns if non-Chinese reference standards were used for comparison.

Testicular volume is largely a reflection of spermatogenesis with over 80% of testicular mass consisting of seminiferous tubules while Leydig`s cells make up the remaining 20%.12,13,14 Since testicular size is more closely related to spermatogenic activity than Leydig cell function, testicular volume may reflect sperm production and male fertility in the future. Therefore, knowledge of normal testicular volume in neonates might have some predictive values of clinical importance. For instance, it has been hypothesized that some of the problems in adulthood may be due to testicular dysgenesis in fetal life.15 A well-described example is seen in Denmark and

Finland, where it was observed that Danish men have a 4-fold higher incidence of testicular cancer and poor semen quality than the Finnish men do.15 The possible explanation for this was

14 found in a study16 that demonstrated that Danish boys had smaller testes as neonates and throughout infancy than the Finnish boys did. In addition, determination of the normal testicular volume is necessary since the fetal testes secrete testosterone that is required for virilisation and continued penile growth and the quantity of testosterone produced is positively related to TV.17

The only published study on penile length in Africa is that from Jarret et al18 in Ibadan. This dearth of knowledge of the normal penile length of Nigerian babies and Africa at large has created a compelling need to embark on the current study. Hence, the aim of the study is to determine the normal penile length and testicular volume in apparently healthy Igbo male neonates. The reference values currently in use were done in Caucasians and may not be applicable to Nigerian babies. These normative values will create baseline data that will serve as a guide to clinicians in appropriate assessment of penile length and testicular volume among the

Igbo population and Nigeria at large.

LITERATURE REVIEW

Penis and Testis

The penis is a phenotypic sex organ of the male.19 It is pendulous, suspending from the front and sides of the pubic arch, and contains the greater part of the urethra.19 It functions in part in urinary expulsion and reproduction.

The testis is the male gonadal sex organ.20 It is seen as a paired glandular organ suspended in the scrotal sacs by the spermatic cords. The primary functions of the testes are to produce sperm and the male hormone testosterone.20

Development of the Penis and Testis

Following fertilization, differentiation into a male requires the XY karyotype.21 By the 6th week of intra uterine life; the fetal gonads appear as an undifferentiated bipotential germinal ridge arising from the urogenital ridge. The determinant of gonadal differentiation into testes requires the presence of the sex-determine region on the Y chromosome (SRY).18 This SRY gene encodes a protein called testis-determining factor (TDF), which ultimately drives the bipotential gonads towards development of testis. Sexual divergence of the external genitalia begins by 8th week of gestation through the action of circulating testosterone and anti mullerian hormome (AMH) produced from the developing testis. Testosterone reaches the genital tubercle where it is converted to dihydrotestoterone (DHT) by 5α reductase enzyme. DHT acting through the androgen receptor on the tubercle and genital fold causes the final differentiation of these structures into penis and scrotum respectively.18

The descent of the testes into the scrotum is biphasic and occurs in the second and third trimesters respectively.22 The initial descent is transabdominal due to the enlargement of genitoinguinal ligament and gubernaculums, while the final descent that occurs at 26-35 weeks through the inguinoscrotal canal is testosterone dependent.22

Penile length

Epidemiologic studies of penile length

Penile length of normal newborn babies has been studied in many western populations.1,3,4,23

Studies performed by Schonfeld and Beebe1 in 1942 with 125 American newborns, Feldman and

Smith3 in 1975 with 63 full term babies of unknown origin, and by Flatau et al4 in 1975 with 100 healthy full term Jewish neonates showed varied results. The consensus reached from above studies is that the mean stretched penile length (SPL) of a normal male newborn is 3.5 ± 0.7cm.24

This length has since been used as a reference value. However, scientists worldwide have been conducting studies to determine the normal values for their own populations.

Ting and Wu10 in 2009 conducted a study on term newborn males in a multiracial Malaysia.

The study involved 105 Malays, 129 Chinese and 16 Indians and the mean SPLs for Malay as well as Chinese infants were reported as 3.5cm ± 0.4cm, and that of Indians was 3.75 ± 0.4cm. In the same context, Lian et al11 in Singapore recorded mean stretched penile lengths similar to that noted by Ting and Wu10 (3.6cm, 3.5cm and 3.8cm for Malays, Chinese and Indians respectively).

The similarity in their mean SPLs could be because Malaysia and Singapore have the same ethnicity and share very similar environmental factors in terms of climate, diet, culture and lifestyle. It was also observed in both studies that the Indian babies out of the three ethnic groups had the longest stretched penile length.

On the other hand, Fok and coworkers9 recorded a mean stretched penile length of 3.0cm in a large study of 4,628 Hong Kong Chinese term infants .This compared positively with SPL of

2.9±0.2cm reported by Sutan-Assin and colleagues25 in their study of 100 Indonesians neonates as well as Chung-Hsing Wang 26,who noted SPL of 2.9±0.4cm in 156 Taiwanese neonates.

An intra-racial similarity seems to exist among Asian countries, especially those located within the same region as shown by the aforementioned studies. For instance, studies10,11 done in some parts of south-east Asia (Malaysia and Singapore) reported similar values in their SPLs

.Likewise, those9,25,26 done in Eastern Asia like China, Indonesia and Taiwan compared positively with each other. Furthermore, studies done in Middle East Asia by AL-Herbish6 in

Saudi Arabia and Kutlu2 in Turkey reported similar stretched penile length of 3.5cm among their neonates. On the other hand, the SPLs among Caucasians1,3-5 compared positively with each other , but there were significant variations when compared with other races.

There is paucity of information from African countries, which leaves little or virtually no data for comparison. However, in 2010, Jarret et al17 in Ibadan, Nigeria studied the SPLs of 264 male neonates within 72 hours of life and reported a mean SPL of 3.4 ± 0.5cm. This value compared positively with that reported among the Caucasians3,4, but relatively shorter than some Asian countries.10,11 The study was a very good attempt but cannot serve as a true representative of the entire ethnic groups in Nigeria as the majority of the subjects were from the Yoruba ethnic group.

Factors influencing penile length

Race\Genetics: Race\Genetic makeup affect the penile length to some extent. A study done by

Fok et al9 documented SPL of 3.0 cm for native Chinese infants in Hong Kong similar to Cheng and Chanione23 findings on Chinese infants born in Canada. Furthermore, Vasudevan et al7 noted the SPL of healthy Indian neonates as 3.6 ± 0.5cm which was also consistent with Cheng and Chanione`s findings on Indian neonates in Canada.23 In addition, Ting and Wu 10as well as

Lian et al11 in their studies in Malaysia and Singapore respectively, reported similar findings in the three major ethnic groups living in both countries. The similar value obtained for each race irrespective of the environment where they live suggests racial\genetic influence.

Hormonal influence: After gonadal differentiation, the presence of testosterone, 5α- reductase and luteinizing hormone are required for continued penile growth.27 Defects occurring at any level will result in abnormal male sex development.27 The clinical manifestation of the abnormality depends on the timing of the occurrence during embryonic and fetal development.27An abnormality occurring before 12 weeks of gestation results in ambiguous genitalia in a genetically male infant. However, an abnormality occurring after 14 weeks of gestation is likely to result in micropenis.28 Furthermore; gonadal males with deficiency in 5α- reductase will not develop normal male external genitalia.22 This is in agreement with Sasaki et al.29 findings in Japan, who observed that some of the patients with micropenis had deficiency of

5α-reductase.

Environmental Factors

Environmental factors such as culture, diet, chemicals and pollution exposure have been linked to small penile sizes at birth.30 The chemicals could be from a synthetic source such as phthalates and plasticizer (for making plastics, pesticides) or from a natural source like lavender oil.31

Swam et al32 in USA in 2008, noted decreased penile size, shorter anogenital distance and incomplete descent of testicles in newborn sons of women with high blood level of phthalates.

Birth Weight and Body Length

There have been conflicting results with regard to the relationship between penile length and growth parameters of birth weight and body length. Fok et al9 and Flatau et al4 as well as

Assawabumrungkul and Pichetsin8 documented a weak but significant positive correlation between penile length, birth weight and body length. In addition, Kutlu2 noted a positive correlation between the SPL and body length but not with birth weight. Contrary to the above findings, Cheng and Chanione22 found no significant correlation between penile length and birth weight as well as body length. A potential explanation for a positive link between penile length with birth weight and body length is that the development of penis, body length and head circumference in the intra uterine life may be under the control of the same growth factors. This can be inferred from the clinical manifestations of congenital growth hormone deficiency and

Laron syndrome (growth hormone receptor insensitivity).33 The manifestations include low birth weight, micropenis and microcephaly34, which implies that growth hormone and IGF-1 are strong determinants of fetal growth and male sexual differentiation, thus the penile length.34

However some authors 22,35 suggested that penile length and fetal growth are largely regulated by independent growth factors. This submission was supported by studies35 done in patients with androgen insensitivity syndrome that presented with micropenis but had normal birth weight and

20 length. From the study, it was concluded that testosterone is a major determinant of penile length but plays a minor role in fetal weight gain.35

Gestational Age: The penis after developing at nine weeks of gestation, continues to increase in length in utero until birth and afterwards. Penile length in Caucasoid preterm is related to gestational age by the equation D =2.27+0.16×GA. Where D is the penile length in centimeters and GA is the gestational age in weeks.4 Fok and colleagues9 documented a positive correlation between the penile length at birth and gestational age in a large-scale study that involved construction of a normogram on gestation specific penile length from 37 to 42 weeks of gestation. Their report was also similar to the findings of Cheng and Chanione22 in Vancouver as well as Assawabumrungkul and Pichetsin8 in Thailand. However, Kutlu2 found no correlation between stretched penile length and gestational age.

Abnormalities of the penis: Abnormalities of the penis might affect the penile length resulting in micropenis, defined as a normally formed penis that is 2.5 SD below the mean size of a reference value.37 Micropenis results from hormonal abnormalities that occur after 14 weeks of gestation. The most common causes include hypogonadotropic hypogonadism (Kallman`s syndrome) and hypergonadotropic hypogonadism (Klinefelter syndrome).38 Other conditions include Prader-Willi, Noonan and Robinow syndromes. Occasionally micropenis may be idiopathic or a normal variant in the population.27

Testicular Volume

The normal testicular volume in neonates varies from 0.27 ml to 2.5ml 39-48, 58-63 with an average of 1ml40. These reference values were derived from previous studies.41-48, 58-63 Chin and coworkers41 in Taiwan in 1998 measured the normal testicular volume in 430 Taiwanese neonates using Prader orchidometer and reported the testicular volume as 1.35 ± 0.3ml.

Similarly, Matsuo and Colleagues in 2000 42 carried out a study in Japanese boys and recorded

1.2ml as the testicular volume in neonatal period. The above results were consistent with the findings of Beres et al43 in Hungary, in 1989 who reported an average testicular volume of 1.29

± 0.01ml in neonates using Hynie´s testometer. In contrast to the Ting and Wu10 findings in

Malaysia that reported a much larger volume in the three ethnic groups studied( 2.5 ± 0.6ml in

Malay, 2.4± 0.5ml in Chinese and 2.0 ± 0.4ml in Indian infants) using Prader orchidometer.

Main et al16 in 2006, measured the testicular volume of Finnish and Danish newborn boys using ultrasonography and reported 0.98ml and 0.95ml respectively. This is smiliar to findings by

Preiksa et al5 in 2009 in Lithuania who reported an average testicular volume of 0.9±0.3ml in

712 healthy newborn males. Surprisingly, Kuijper et al44 in Amsterdam, in a study of ultrasonographically measured testicular volumes in 0 to six years old boys, recorded a much lesser value of 0.27ml in neonates..

The wide variation in values from the above studies was attributed to the lack of standardization in the instruments used. Measurements by Prader orchidometer tend to overestimate testicular volume especially in small testes as it measures not only the testis but also the epididymis as well as the skin.45,46 Furthermore, the smallest bead in Prader orchidometer is 1 ml, making it impossible to get values less than 1 ml.45,46,47

Factors that affect Testicular Volume

Race/Ethnicity: No consensus has been reached on the influence of race or ethnicity on infant testicular volume.43,44,48 Although several studies41-43,45-48 have been done on testicular volume among different countries worldwide, the emphasis was mainly on the different methods of measurements rather than differences based on racial or ethnic background. However, Kuijper et al44 in Amsterdam studied a multi-ethnic group of Caucasians, Asians, Mediterranean and

Africans living there and found no difference between the various ethnic groups. On the other hand, Main et al16 reported a larger testis size in Finnish neonates compared to Danish boys.

Although the phenomena could be due to genetic difference between the two countries, it may also reflect an adverse environmental influence on testicular development.16

Environmental Factors: The key determinant of testicular volume is the number of sertoli cells, which proliferate in fetal and early postnatal life.15 Therefore, any interference with this stage of proliferation might affect the testicular volume as some studies have linked exposure to phthalates with testicular dysfunction.15,52 Also early introduction of soy formula milk (SFM) at postnatal life, can suppress FSH secretion because of its high level of plant oestrogen. As a result, this can potentially inhibit testosterone production by the testis.53-54Furthermore, studies55,

56 have shown that exposure to maternal smoking in the intra uterine life is associated with smaller testes size and poor semen quality later in life.

Relationship between penile length and testicular volume

Testicular volume is made up of testicular mass which consist of seminiferous tubules and the

Leydig cells.18 The fetal Leydig cell secretes testosterone, which is one of the hormones needed for development of male external genitalia including the penis.18 Subsequently, a certain level of

23 this hormone in addition to luteinizing hormone secreted by the fetal pituitary gland, under the control of luteinizing hormone releasing hormone(LHRH) is needed for continued penile growth in utero and afterwards.18,22 Therefore, normal and intact hypothalamus-pituitary-gonadal axis is needed for adequate penile length and testicular volume at birth. Additionally, studies done by Preiksa et al5 as well as Semiz and co-workers57 on penile length and testicular volume in infants showed a significant positive correlation between penile growth and testicular volume.

Methods of measuring penile length

The conventional and the most acceptable way of measuring penile length is the one proposed by

Schonfeld and Beebe1 in USA in 1942. The stretched penile length was measured with a wooden ruler. This method was supported by the fact that Schonfeld demonstrated correlation between the stretched and erect penile length (r =0.983, p<0.01).1,6 However, this method was criticised by Sepkowitz58 who was of the opinion that the penis exists in two forms in nature: flaccid or erect and should be measured in these forms and not the maximally stretched flaccid penis, which simply does not exist in nature. A new method was introduced by Ozbey et al59 in Britian, in which a piston was fixed to the cut end of a 10ml syringe and was partially withdrawn causing suction to draw the penis into the injector. Afterwards the penile length was read off from the attached scale. This method though accurate is quite discomforting and as such not popular.6

Methods of measuring testicular volume

There are different methods of measuring testicular volume such as orchidometery, ultrasonography, water displacement and use of calipers and rulers.60 The Orchidometer is the most widely used and there are different types such as Prader, Tukihara-punched ring, Rochester and Seager.61,62 Prader orchidometer is the most popular and it consists of a string of twelve numbered wooden or plastic beads of increasing size from about 1-25 mililitres in width. The beads are compared with the testicles and the volume of the bead that matches most closely in size is read off in ml.47,62,63 Although Prader orchidometer is more practical, inexpensive and less time consuming, it tends to overestimate the testicular volume especially in small testes because it measures the epididymis as well as the scrotal skin.44,47,64

On the other hand, ultrasonography is done by careful measurement of the testes in longitudinal and transverse planes to obtain the length, width and height and the testicular volume is then calculated using various formulae. These formulae include Lambert formula 0.71x Lx W x H64,

π/6(LWH) x 0.52 and Prolate formula (LW) 0.52.65 The Lambert formula is the most accurate formula as shown by a study done by Hsieh et al65 in China. The Prolate formula is associated with less accuracy because of the inherent assumption that testicular width equals its height. That assumption is however, not always the case.65

Several studies that have compared orchidometery and ultrasonography58-61,65-67 concluded that ultrasound measured volume is more precise, shows low variability and correlates well with true testicular volume, and thus should be regarded as gold standard. However, the above studies58-61,

65-67 still found a strong linear positive correlation (R2=0.96) between orchidometer and ultrasound measured volume.

AIM AND OBJECTIVES

Aim:

The aim is to determine the normative values of stretched penile length and testicular volume in apparently healthy term Igbo newborns in Enugu.

Specific Objectives:

The specific objectives are to:

1. establish normative values of stretched penile length of apparently healthy term newborn

males of Igbo extraction,

2. establish normative values of testicular volume of apparently healthy term newborn

males of Igbo extraction,

3. determine the correlation between stretched penile length and birth weight and body

length.

4. determine the correlation between testicular volume and birth weight and body length.

5. determine the correlation between stretched penile length and testicular volume.

SUBJECTS AND METHODS

Study Location

Description of Enugu and its characteristics:

Enugu is the capital city of Enugu State in Nigeria.66 It is located in southeastern area of Nigeria and is largely populated by members of Igbo ethnic group. The city has a hilly geography with a population of 722,664 inhabitants.67 It has a tropical savannah climate with a mean daily temperature of 26.7oC and average annual rainfall of 2000 millimeters.66 Enugu was a major coal mining area in West Africa and was once famed for producing half the world total output of palm kernels. Subsequently after the civil war and with the oil boom, trading became the dominant occupation of the inhabitants followed by civil services (white-collar job).66 There are more than 25 hospitals in Enugu. Three are tertiary hospitals while the rest are being managed by private sectors.

The study was hospital based involving three hospitals. These hospitals included University of

Nigeria Teaching Hospital (UNTH), Enugu, Enugu State University Teaching Hospital

(ESUTH), Enugu and Mother of Christ Specialist Hospital (MCSH), Enugu. These hospitals were purposively chosen because they enjoy very high patronage of patients.

Description of the study centers and their characteristics:

University of Nigeria Teaching Hospital is a tertiary health facility that is 21 kilometers from

Enugu Metropolis. It is a 500 -bed hospital equipped with infrastructure for all specialties including Obstetrics and Paediatrics. It has an annual delivery of 600 babies with average number of 50 deliveries per month. ESUTH is also a tertiary health facility that offers regular

Obstetric and Paediatric care with annual delivery of 1600. The MCSH is a faith based secondary health facility, managed by Roman Catholic Church, and offers Obstetric and Pediatrics services with an annual delivery of about 1200. The study was carried out in the labour wards and lying- in wards of the chosen hospitals.

Study design

The study was hospital based, cross-sectional and descriptive. Subjects were enrolled consecutively within the first 72 hours of life.

Determination of the minimum sample size:

The sample size was calculated for each gestational age 37 weeks through 42 weeks using the formula: n = (Zæ) ² (S) ²/ (D) ².68

Where: n = the uncorrected sample size estimate

Zæ= the standard normal coefficient which is 1.96 at 95% confidence interval

S= the standard deviation

D= the desired precision level expressed as half of the maximum acceptable confidence interval width.

Using the study by Jarret et al, 17 the values are as follow:

Zæ=1.96

S=0.49cm

The maximum permissible acceptable confidence interval is 5% around a mean value of 3.4cm as reported by Jarret et al.17 Five percent of 3.4cm =0.17cm and half of this figure is 0.085.

This means that D= 0.085

Thus n= (1.96)² × (0.49)²/ (0.085)² =128

The calculated sample size of 128 was applied to each gestational age in weeks to get a total expected sample size of 128x6=768. However, because of the natural concentration of deliveries at GA of 38 to 40 weeks observed in the three hospitals, the ratio of deliveries at each gestational age was determined over one year period in the three hospitals and the proportional observations per GA are shown in the table below:

Table 1: Stratification of study subjects according to gestational age

GA One-year %age Expected Observed

pre-report Sample size sample size

37 235 8 61 65

38 850 25 192 203

39 966 26 200 211

40 932 28 215 227

41 283 9 69 73

42 130 4 31 32

Total 3400 100 768 811

To ensure that the sample size collection was spread across the study centers; the proportionate sampling method68 based on the ratio of annual deliveries was applied by converting the number of deliveries to percentages as follows: 18%, 35% and 47% for UNTH, MCSH & ESUTH giving

146, 284 and 381 respectively.

Subjects

Enrolled subjects for the study were consecutive apparently healthy term male neonates of Igbo extraction with appropriate weight, delivered in these hospitals within the first 72 hours of life during the period of study.

Definition of terms

A term baby is one delivered between 37 completed weeks to 42 weeks of gestation.69 While, an apparently healthy baby is a baby who appears to be well.69

Exclusion Criteria

1. Neonates with ambiguous genitalia or suspected endocrinological disorders

2. Babies with undescended testes and hydrocele.

3. Babies with dysmorphism or multiple congenital abnormalities

4. Neonates less than 2.5kg and more than 4.0kg

5. Neonates of non-consenting mothers

Ethical Considerations

Ethical approval was obtained from the Health Research and Ethics Committee of University of

Nigeria Teaching Hospital Enugu (Appendix A).Written Permissions(Appendices B $ C) were also obtained from Enugu State University Teaching Hospital and Mother of Christ Specialist

Hospital.

Informed written consent (Appendix D) was obtained from the parent/guardian of each subject after delivery. Details of the study were explained to the parents and only those who gave consent were included in the study.

Data collection

Information obtained from the history and physical examination were entered into a purpose- designed proforma (Appendix E). Subjects were consecutively enrolled from both the labour ward and lying –in ward. An informed written consent (Appendix D) was obtained from the mothers. Thereafter, the mothers were interviewed to obtain biodata such as age, sex, tribe of their babies etc (see proforma: section 1). Antenatal history and condition of each infant were obtained from the mothers and hospital records. A general examination was done for each neonate to determine the gender and other features of inclusion and exclusion criteria.

Gestational age was calculated to the completed weeks and was determined from the maternal last menstrual period (LMP), if the mother had regular menstrual cycles and was certain of her menstrual history. The gestation of each neonate was also assessed using the new ballard score.70

Only neonates whose calculated gestation agreed within two weeks with that assessed postnatally were included.

Measurements:

Quality Control

The research was carried out by the researcher with two research assistants, who were trained in all aspects of the methodology including measurement of weight, length, SPL, testicular volume and adequate filling of forms. A standard operating procedure was formulated to ensure uniformity. To validate the accuracy of the measurements, a pilot study was conducted; the researcher and the two assistants repeated the measurements on 30 babies in the first week of research. The inter-observer difference was tested using the kappa analysis and it was 0.95 for penile length and 0.96 for testicular volume indicating that there were no significant differences in the three sets of measurements. In addition, there were three consecutive measurements of the

SPL and TV by each investigator. The precision of each investigator and measurements was assessed by establishing the intra-observer reliability obtained from the first 30 babies. The intra- observer reliability was 97% (Cronhbach`s Alpha=0.97), showing that the intra observer error was minimal and not significant. Thereafter the researcher and the assistants continued with their individual measurements.

Measurement of Body Length

The body length was measured to the nearest 0.1cm using an infantometer (Seca), model:

210182109. The naked neonate was placed in a supine position, eyes looking upwards with the crown of the head held steadily against the headboard by the research assistant. The legs were straightened by placing a hand on both knees and the measuring footplate was slid to bring it in contact with the soles of the feet. The distance between the top of head and heel was measured in cm and recorded appropriately.

Measurement of Weight

All subjects were weighed naked on a digital weighing scale (Seca, Vogel and Halke) sensitive to the nearest 10 grams. It was set at zero point before use and at the beginning of each measurement; the accuracy of the scale was determined by measuring a known standardized weight.

Measurement of the stretched penile length

The stretched penile length (SPL) was measured using the Schonfeld method. The subjects were placed in supine position and the perineum properly exposed. The penile length was measured to the nearest 0.1cm using a disposal ruler. The SPL was determined by measuring the stretched distance from the pubic symphsis to the tip of the glans penis. The pubic symphsis was identified by palpation and the straight edge of the ruler was placed against the pubic symphsis from the dorsal side of the penis. The penis was subsequently stretched alongside the ruler to the point of maximum resistance to palpate the glans penis. A mark was made on the ruler at the level of the top of the glans penis excluding the foreskin and the value read off in cm.

Measurement of Testicular Volume

Testicular volume was measured with a Prader Orchidometer (ZKL-135-H), ESP Model. It has a sensitivity of less than 50%, this meant that a volume differential of 10%, 15%, 20%, 25% etc was not detected by orchidometery. The Prader orchidometer consists of 12 ellipsoid testis models graded from one ml to 25ml (1 to 6, 8, 10, 12, 15, 20 and 25 ml) against which each testis was compared. The scrotal skin was stretched over the testis in a warm room and the beads were compared by visual inspection with the testes. The volume of the bead that matches most closely was read off in ml. Both the right and left testes were measured. A testis size that was in -

33 between two standard ellipsoid volumes was determined by calculating the mean between the larger and the smaller ellipsoid sizes.10

Data analysis:

All the data obtained were recorded and analyzed using the Statistical Package for Social

Sciences (SPSS) version 17.0. Data were presented in prose, tables, figures and graphs. The means, standard deviations and 95% confidence intervals of the continuous variables (SPL, TV,

BW and BL) were reported. The smoothed centiles (3rd to 97th percentile values) for SPL and TV by gestational age were calculated. Pearson Correlation coefficient (r) and linear regression analyses on the established correlations were conducted to express the linear relationship between stretched penile length and testicular volume, SPL and birth weight as well as body length and testicular volume with birth weight and body length. Formula for predicting SPL using TV was derived. P-value less than 0.05 was regarded as statistically significant.

RESULTS

The study lasted six months; from April to September 2012 .Eight hundred and eleven neonates

were studied. 146 neonates were from UNTH, 284 from MCSH, while 381 newborns were from

ESUTH. The characteristics of the subjects were shown in Figure 1 and Table II-V.

Figure1 shows the distribution of subjects according to gestational age. The minimum gestational

age was 37weeks, while the maximum was 42 weeks with mean gestational age of 39.17 weeks

± 1.24

The majority of the subjects were delivered between 38 to 40 weeks of gestation.

Gestational Age (weeks)

Fig 1: Distribution of 35 subjects by Gestational Age Table II shows the distribution of birth weight of the subjects .The minimum birth weight was

2.5kg while the maximum was 4.0kg with mean birth weight of 3.36± 0.42kg. The majority of the patients weighed between 3.0kg and 3.5kg.

Table 1I: Distribution of Birth Weight (kg) of subjects

Birth weight(kg) Frequency(n) %

2.500 to 2.749 72 8.9

2.750 to 2.999 72 8.9

3.000 to 3.249 195 24.0

3.250 to 3.499 97 12.0

3.500 to 3.749 189 23.3

3.750 to 4.000 186 22.9

Range: 2.5 -4.0kg 95% confidence interval: 3.33 -3.39kg

The majority of the subjects had body length between 49.1cm to 51.0cm, with a range of 45 to

55cm and mean value of 51.12 cm.±2.03cm.(Table III)

Table III: Distribution of body length (cm)

Body length (cm) Frequency %

≤ 47 25 3.1

47.1 to 49.0 99 12.2

49.1 to 51.0 331 40.9

51.1 to 53.0 239 29.5

53.1 to 55.0 117 14.4

Range: 45.0 – 55.0 cm 95% confidence interval: 51.06-51.31 cm

The mean stretched penile length of term newborns was 3.46 cm ± 0.44cm .Consequently the lower and upper limits (±2.5SD) were 2.36cm - 4.56cm and the 95% confidence interval around the mean was 3.43-3.49cm. (Table IV). On the other hand, -2SD corresponded to 2.58cm.

Table IV: Distribution of Stretched penile length (cm) of subjects

Stretched penile length(cm) Frequency %

<2.50 6 0.7

2.51 to 3.00 217 26.8

3.01 to 3.50 275 33.9

3.51 to 4.00 272 33.5

4.01 to 4.50 38 4.7

4.51 to 5.00 3 0.4

Range: 2.50- 4.70 cm 95% confidence interval: 3.43 -3.49cm

The smoothed percentiles for stretched penile length by gestational age were calculated and presented in Table V. The 50th percentile corresponded to the median value of stretched penile length for each gestational age. The values at 37, 38, 39, 40, 41 and 42 weeks were 3.24cm,

3.31cm, and 3.38cm, 3.45cm, 3.52cm and 3.59cm respectively. The 3rd percentiles corresponded to -2SD while the 97th percentiles corresponded to +2SD. The values that corresponded to -2SD at each gestational age 37 to 42 weeks include 2.61cm, 2.66cm, 2.71cm, 2.76cm, 2.81cm and

2.85cm.

Table V: Smoothed percentiles for stretched penile length (cm) by gestational age (weeks)

Gestational age Percentiles

3 5 10 25 50 75 90 95 97

37 2.61 2.64 2.73 2.84 3.24 3.62 3.86 4.00 4.13

38 2.66 2.71 2.80 2.94 3.31 3.68 3.90 4.03 4.19

39 2.71 2.78 2.86 3.05 3.38 3.75 3.94 4.06 4.25

40 2.76 2.86 2.93 3.16 3.45 3.81 3.97 4.09 4.31

41 2.81 2.93 3.00 3.26 3.52 3.88 4.01 4.12 4.37

42 2.85 3.00 3.07 3.37 3.59 3.94 4.05 4.14 4.43

The mean testicular volume was 1.74ml ± 0.62ml with a range of 1ml to 3mls and the 95 % percent confidence interval around the mean was 1.698-1.783 ml as shown in Table VI.

Subsequently, the smoothed percentiles for testicular volume by gestational age were calculated and shown in Table VII. There was no observed difference in testicular volume for each gestational age below the 10th percentile (Table VII)

Table VI: Distribution of testicular volume (ml) of subjects

Testicular Volume(ml) Frequency Percentage

1 to 1.50 354 43.6

1.51 to 2.00 282 34.8

2.01 to 2.50 114 14.1

2.51 to 3.00 61 7.5

Range: 1-3mls 95% Confidence interval: 1.698-1.783ml

Table VII: Percentiles for testicular volume (ml) by gestational age (weeks)

Gestation Percentiles weeks 3 5 10 25 50 75 90 95 97

37 1.00 1.00 1.00 1.00 1.48 2.00 2.33 2.61 2.74

38 1.00 1.00 1.00 1.08 1.59 2.06 2.43 2.69 2.81

39 1.00 1.00 1.00 1.16 1.70 2.12 2.53 2.77 2.88

40 1.00 1.00 1.00 1.24 1.81 2.18 2.63 2.85 2.95

41 1.00 1.00 1.00 1.32 1.92 2.24 2.73 2.93 3.02

42 1.00 1.00 1.00 1.40 2.03 2.30 2.83 3.00 3.09

Pearson’s correlation test that was used in assessing the association between the variables (SPL,

TV, BW and BL) demonstrated significant positive correlation between stretched penile length and testicular volume (r=0.592, p = 0.001). Similarly, there was a positive correlation between stretched penile length and body length (r= 0.343, p=0.001). However, there was a positive correlation though weak between stretched penile length and birth weight (r=.0.229, p=0.001).

On the other hand, the testicular volume correlated positively with body length(r=0.301, p=0.001) as well as birth weight(r=0.247, p=0.001) though weak as shown in (Table VIII).

Table VIII: Pearson’s correlation between Stretched penile length and Testicular volume with growth parameters of Birth weight and length.

Correlation(r) Testicular volume Stretched penile length

r p r p

Birth weight 0.247 0.001 0.229 0.001

Birth length 0.301 0.001 0.343 0.001

Linear regression analysis showed a significant correlation between testicular volume and stretched penile length (p=0.0001, R²=0.356) (Figure 2). This shows that 35.6% of variations in stretched penile length are explained by testicular volume. The following formula can be used for predicting SPL using TV as the independent variable (Table IX).

SPL =2.720 + (0.426× Testicular volume ml).

In addition, the linear regression between stretched penile length and length at birth showed a statistically significant correlation (p=0.0001, R²= 0.117) (Figure3 and Table X), implying that

11.7% of variations are explained by body length.

The linear regression between SPL and BW showed that only 4.8% of the variations can be explained by birth weight (p=0.0001, R² =0.048) (Figure 4). Also, the linear regression between gestational age and SPL (p=0.0001, R² =0.054) (Figure 5 and Table XI) implied that only 5.4% of the variations are explained by gestational age. A multiple regression was run to predict stretched penile length from gestational age and testicular volume. These variables statistically significantly predicted stretched penile length (p =0.0001). (Table XII).

Table IX: Linear Regression for Stretched penile length versus Testicular volume

Constant Std .Error t Sig

α 2.720 0.037 73.190 .0001

Testicular 0.426 .020 21.146 .0001

Volume(ml)

SPL =2.720 + (0.426× Testicular volume ml)

Table X: Linear Regression for Stretched penile length versus Body length

constant Std. Error T Sig

α -.341 .367 -.931 .352

Body length 0.074 .007 10.377 .0001

Table XI: Linear regression for Stretched penile length versus Gestational age

Constant Std. Error t Sig

α 0.754 0.037 1.891 .059

Gestational age 0.069 .020 6.791 .0001

Table XII: Multiple regression of Stretched penile length versus Gestational age and

Testicular volume.

constant t Sig 95%confidence

interval

α 1.555 4.724 0.000 0.909-2.201

Testicular 0.409 0.409 0.000 0.369-0.449 volume(ml)

Gestational age 0.030 3.562 0.000 0.014-0.047

Figure 2: Linear regression showing the correlation between SPL and TV

Figure 3: Linear regression showing the correlation between SPL and BL

Figure 4: Linear regression showing correlation between SPL and BW

Figure 5: Linear regression showing correlation between SPL and GA

Figure 6: Linear regression showing the correlation between TV and BL

Discussion

The mean SPL of term Igbo babies in this study was 3.46cm ± 0.44cm .This mean SPL is similar to SPL of 3.5± 0.4cm reported by Feldman and Smith3 among the Caucasians as well as

3.49 ± 0.4cm reported by Boas and colleagues71 in Denmark and Finland. However, it was longer than the SPL documented by some authors in Eastern part of Asia; Sutan-Assin et al25 in

Indonesia (2.86 ± 0.23cm), Wang and De-Line26 in Taiwan (2.9 ± 0.4cm) and Fok et al 9 in

China (3.0±0.4cm). On the other hand, the SPL of Igbo babies was relatively shorter than the values reported in Middle East and Southeast Asia by Al-Herbish6 in Saudi –Arabia (3.55±

0.57cm), Vasudevan et al7 in India (3.75±0.4cm) as well as Ting and Wu10 in Malaysia

(3.6±0.4cm) and Carmudan et al24 in Turkey (3.65±0.27cm). The discrepancies in the mean SPLs across countries could be explained by genetic heterogeneity of various ethnicities and racial groups in addition to environmental influence. In Nigeria, the mean SPL of 3.4±0.49cm reported by Jarret and co-workers18, was within the same range with the mean SPL noted in Igbo babies.

However, further studies are needed to fully evaluate the tribal factors in Nigeria.

Micropenis is usually defined as a normally formed penis that is 2.5 SD below the mean size of a reference value.37 It was formally defined as any value less than 1.9cm in newborns.1,3,9,28,72 In this study, a SPL less than 2.36 (mean-2.5SD) is defined as micropenis. Ting and Wu10 reported that a SPL of 2.5cm was considered as micropenis for Malay term neonates, Boas et al71 reported this length as 2.49cm, Preiksa et al5 as 2.45cm, AL-Herbish6 from Saudi Arabia as 2.13cm and

Fok et al9 from China as 2.00cm. In Ibadan, Jarret et al 18reported 2.26cm as the cut-off value for micropenis, slightly different from the results of present study. These results challenge the usage of a single standard value claiming applicability and universality for all. However, some investigators9,23 are proposing that the definition of micropenis should be adjusted to penile

53 length of 2SD below the mean as using 2.5SD below the mean would make the number of suspected cases to be much lower (0.3% of the population). For instance, in some case series reported by Sasaki and colleagues29 in Japan, one infant with penile length of 2.4SD below the mean was proven to have 5α –reductase deficiency and required hormonal (5α- dihydroxytestosterone) therapy. The above-mentioned baby would not have been identified by using the cut-off of 2.5SD below the mean. Therefore, based on the above findings, the definition of inadequate penile length should be adjusted to a penile length below the third percentile (mean-2SD). However, definition of abnormal values as -2SD will perennially face the criticism of declaring 3%(below the 3rd percentile) of the population as having micropenis, while it is still possible that some are constitutionally small or may have failed to reach their potential size but did not fall into the percentile-based definition of micropenis. Nevertheless, if 2SD below the mean was used, micropenis in Igbo babies would have been defined as any SPL less than 2.58cm instead of 2.36 cm as currently reported, hence increasing the number of suspected cases.

The mean TV (1.74mls) in this study was similar to the TV (1.73mls) documented by Semiz et al

57 in Turkey but slightly higher than the findings of Chin and coworkers41 in Taiwan (1.35mls) as well as Matsuo and colleagues42 in Japan (1.2mls ) and Beres et al 43 in Hungary. However, it was relatively lower than the TV of 2.4mls reported by Ting and Wu10 in Malaysia. There are appreciable differences in the values of TV reported by the aforementioned studies, though they all used Prader orchidiometer for measurement but for Beres et al 43 that used Hynie`s testsometer. The differences can be explained by lack of precision and low sensitivity associated with Prader orchdiometer. On the other hand, TV reported in this study was much higher than the values of ultrasound measured testicular volume reported in some studies.44,48 The observed

54 significant differences could be explained by lack of standardization in the methodologies.

However, racial and ethnic influence cannot be ruled out entirely.

There was statistically significant moderate positive correlation between SPL and TV, but the clinical significance was not so strong since only 35.6% of the observed variation in SPL could be explained by the variability in TV. This positive correlation is consistent with the findings of

Prieska et al5 in Lithuania as well as Semiz et al57 in Turkey and it can be explained by the fact that the fetal testes secrete testosterone, which is one of the hormones needed for continued penile growth. In addition, the quantity of testosterone produced is positively related to testicular volume. A typical representation is seen in patients with androgen insensitivity syndrome that manifest with impaired penile growth because of lack of effect of testosterone on the organ (end organ resistance syndrome) as well as in testicular dysgenesis/agenesis (failure of the testes to secrete testosterone). In contrast to this, Ting and Wu 10reported a negative correlation between

TV and SPL for each ethnic group in multi- ethnic Malaysia. The reason for the negative correlation could not be explained.

There was also statistically significant positive correlation between SPL and body length at birth, but weak clinical significance since only 11.4% of the variation in SPL was explained by variability in body length. Similar to the findings of Fok et al 9, Lian et al 11as well as Flatau et al4, Boas et al71 and Camurdan et al.24 In contrast to the above findings, Cheng and Chanoine23 found no such correlation, which may be attributed to smaller number of subjects (<50) in their study. Furthermore, there was a statistically significant positive correlation though weak between

SPL and birth weight similar to the findings of Fok and colleagues9 as well as Camurdan et al 24.

However, Boas et al 71and Akin et al 72found no correlation between SPL and birth weight. The discrepancy in results could be explained by studies in patients with androgen insensitivity that

55 manifested with micropenis d normal birth weight. This shows that testosterone is a major determinant of penile length but plays a minor role in fetal weight gain.35 In adult studies,

Ponchietti et al73 reported that penile dimensions correlated with other anthropometric measurements such as height and weight suggesting that penile length should be considered as one of the anthropometric measurements. This positive correlation especially in body length could explain the lower mean SPL reported in East and Southeast Asia 8,9,25,26 where majority of the populace are short. The mean anthropometric differences, especially with regard to height of various ethnicities may account for the varying mean SPL of different populations.

Correspondingly, there was a statistically significant positive correlation between TV and birth weight as well as body length.

From the above findings, it becomes meaningful to evaluate and calculate the individual expected values for SPL of the newborns that this sample represents, based on testicular volume of each of the male neonates at birth with the use of the formula generated. However, the nature of these correlations on a much more comprehensive scale can only be understood via the contribution of future studies by various centers around the world on penile anthropometry of newborn males.

Conclusions

1. The mean SPL and TV of term healthy Igbo neonates from this study were 3.46 ± 0.44cm

and 1.74 ± 0.62mls respectively.

2. The percentiles of penile length and testicular volume created should serve as a useful

guide to clinicians in the interpretation of relevant data on Igbo newborn babies.

3. There was a moderate positive correlation between SPL and TV (r=0.592 , p=0.001)

4. There were positive correlations though weak between SPL and birth weight(r=0.229,

p=0.001) as well as body length (r=0.343, p=0.001).

5. Testicular volume correlated positively with birth weight (r=0.247, p=0.001) and length.

(r=0.301, p=0.001).

Recommendations

1. Routine evaluation of the external genitalia of newborns should form an integral part of

the neonatal physical examination. This will lead to early detection of any abnormality

and prompt institution of appropriate management.

2. The normative values established from this study should be used as reference values for

Igbo babies and near-reference values for Nigerian babies at large.

LIMITATION OF THE STUDY

This study is limited in the generalization of findings to the population because it was a cross- sectional study conducted in urban and peri-urban areas. A randomized controlled study comparing the SPL of Igbo neonates with that of non-Igbo neonates, and involving the rural population would have made it a stronger study.

The exclusion of term low birth weight babies was also a limitation.

Lines of Future Research

1. A multistate study that will represent all the 370 ethnic groups74 in Nigeria may need

to be conducted to get a reference value that will be a true representation of the

Nigeria population.

2. Further studies that will compare testicular volume among different ethnic groups.

3. A study that will involve low birth weight and preterm babies.

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Appendix A

APPENDIX B

APPENDIX C

APPENDIX D:

Determination of normal penile length and testicular volume in healthy Igbo newborns in

Enugu.

Information and consent form

Dear mothers, early detection of abnormal penile sizes and early establishment of diagnosis of the underlying disease; will help prevent some medical and psychosocial effect of these conditions on your child. I hereby, invite you and your baby boy to participate in this research study under DR CHIKANI UGO N of Department of Paediatrics UNTH, Enugu. This study is purely for research purposes and will last for 3-4 months with no stress on you or your baby.

Your baby will have just a single contact with the researcher throughout the study. However, the mother will simply give information on baby`s antenatal history. Please be part of this study and give your child the opportunity to receive quality examination. Your baby will be examined generally with plastic medical devices. The procedure is totally safe and non- invasive (no incisions/ cuts). It will be gently done to minimize possible discomfort.

Your identity and that of your baby as well as the information obtained in this study will be handled with confidentiality. The immediate benefit in this research study is that in the course of examining the baby, if found to have an abnormal genitalia will be referred to the appropriate unit for proper management for a stitch in time saves nine. Please be part of this research to

73 create a healthy and bright future for your child. However, participation is voluntary and you may refuse to give consent without being denied access to adequate medical care.

For questions and complaints, you can contact the researcher or ethics committee with these numbers 08037431002 or 0803332469 respectively.

Thank you in anticipation of your co-operation and participation.

ASSENT FORM (CONSENT)

I ______have read the consent form which was duly explained to me on the nature, benefits and the risk of this study. I have also been given opportunity to ask questions which were all explained and I understood them very well. I hereby voluntarily without any form of coercion or inducement give my consent that my baby will participate in this study.

…………………………………. ……………………………………….

Name of parent/guardian Signature of parent/guardian/date

…………………………………. ………………………………………..

Name of Researcher Signature of Researcher/date

………………………………… ……………………………………….

Name of Witness Signature of Witness/date

APPENDIX E

Determination of normative values of stretched penile length and testicular volume in apparently healthy term Igbo neonates in Enugu.

RESEARCH PROFORMA

SECTION 1: BIODATA OF BABY

1. Name code______

2. Serial number______3. Date of enrolment______

4. Hospital No______5. Date of birth ______

6. Age ______(hrs) 7. Tribe ______

8. Sex ______

9. Address code ______

10. Contact phone number______

Gestational age from LMP:------in weeks

Gestational age from Ballard score:------in weeks

SECTION II: EXAMINATION

Vital signs

Temperature oC

Pulse rate (beats/min)

Respiratory Rate (breaths/min)

Anthropometry

Weight (kg)

Length (cm)

EXAMINATION OF THE GENITALIA

Normal appearance Yes No

(Typical male phenotype)

1st Measurement 2nd Measurement Mean

Stretched penile length (cm)

Testicular Volume (ml)