IN THE NAME OF GOD Cervical insufficiency
FARZANEH .VASHGHANI FARAHANI DEARTMANT OF OB&GYN TUMS JUIY /9/2018
INTRODUCTION
Classically, the term „cervical insufficiency‟ was used to describe a disorder in which painless cervical dilation led to recurrent second trimester pregnancy losses/birth of otherwise normal pregnancies.
Although structural cervical weakness is the source of some preterm losses/births, most are caused by other disorders, such as decidual inflammation/infection, hemorrhage, or uterine over distension.
Historical factors suggestive of cervical insufficiency include a history of second trimester pregnancy losses/deliveries, especially in the setting of short labors or progressively earlier deliveries in successive pregnancies. Short cervical length — Cervical length is normally stable between 14 and 28 weeks, and declines substantially after 28 to 32 weeks.
2nd centile at 15 mm
5th centile at 20 mm
10th centile at 25 mm
50th centile at 35 mm
90th centile at 45 mm
The median cervical length is 40 mm before 22 weeks, 35 mm at 22 to 32 weeks, and 30 mm after 32 weeks. Cervical length is not significantly affected by parity, race/ethnicity, or maternal height.
Cervical risk factors .
Congenital factors
Collagen abnormalities : Alterations in the regulation of type I collagen expression,and genetic disorders affecting collagen (Ehlers-Danlos syndrome) have been associated with increased risk of preterm birth .This may explain familial history of cervical insufficiency .
Uterine anomalies :The risk of second trimester preterm birth is increased with uterine anomalies, including canalization defects (septate uterus), unification defects (bicornuate uterus), and even arcuate uterus .
Diethylstilbestrol (DES) exposure
Biologic variation :The wide range in normal cervical length (the 10 th and 90 th percentiles are 25 and 45 mm, respectively) is due, in part, to biologic variation, but may also result from premature cervical effacement.
Acquired factors
Obstetric trauma : A cervical laceration during labor and delivery, including spontaneous, forceps, vacuum, or cesarean birth .
Mechanical dilation :Cervical insufficiency has also been attributed to rapid mechanical dilation of the cervix during gynecologic procedures [D&C], [D&E], pregnancy termination,
Treatment of cervical intraepithelial neoplasia : It has been associated with an increased risk of subsequent pregnancy loss/preterm birth. (Cervical conization)
Symptoms Physical examination
pelvic pressure, Soft somewhat effaced cervix, with minimal, if any, dilation . premenstrual-like cramping or backache, Tocodynamometry usually reveals no or infrequent contractions at irregular Increased vaginal discharge, intervals A slight change in the color and Application of suprapubic or fundal consistency of vaginal discharge, pressure, or Valsalva, rarely reveals Contractions are absent or mild, membranes in the endocervical canal or vagina. These symptoms have usually been present over several days or Late clinical presentation is characterized weeks, typically beginning around by advanced dilation ≥4 cm and 14 to 20 weeks of gestation. effacement ≥80 % , spotting, prolapsed membranes or ruptured membranes, Contractions that seem inadequate to explain the advanced effacement and dilation.
Imaging : Before 28 weeks of gestation, cervical length by transvaginal ultrasound below the 10th percentile (25 mm) is consistently associated with an increased risk of spontaneous preterm birth. Other sonographic features suggestive of increased risk of preterm birth include separation of the membranes and debris (sludge) in the amniotic fluid. Laboratory : There are no laboratory abnormalities characteristically associated with uncomplicated cervical insufficiency. In some cases, cervical insufficiency is caused by, or leads to, subclinical intraamniotic infection, which can be diagnosed by examination of amniotic fluid from amniocentesis. Cervico-vaginal fetal fibronectin may be positive. Can cervical insufficiency be diagnosed before pregnancy? The diagnosis of cervical insufficiency cannot be made or excluded outside of pregnancy by any test. Evaluation of cervical function with dilators, balloons, or hysteroscopy is not helpful. Ultrasound, MRI, or HSG may reveal a uterine anomaly, which is a risk factor for cervical insufficiency, but is not diagnostic.
DIAGNOSIS : The diagnosis of cervical insufficiency based on historic factors , is defined as:
Painless cervical dilatation leading to at least two pregnancy losses/births before 28 weeks of gestation .
A preferable definition allows the diagnosis of cervical insufficiency to be made in primigravidas or in multigravidas without multiple prior pregnancy losses. Using this definition, cervical insufficiency is defined by :
TVU cervical length <25 mm and/or advanced cervical changes on physical examination before 24 weeks of gestation in women with either:
One or more prior pregnancy losses /births at 14 to 36 weeks, and/or
Other significant risk factors for cervical insufficiency .
The diagnosis of cervical insufficiency is usually limited to singleton gestations because the pathogenesis of delivery at 14 to 28 weeks in multiple gestations is usually unrelated to a weakened cervix.
In addition, preterm labor, infection, abruptio placenta, and bleeding placenta previa should be excluded.
APPROACH TO MANAGEMENT
Women with prior pregnancy losses or preterm births Candidates for history-indicated cerclage : We suggest history-indicated cerclage at 12 to 14 weeks for women who meet all of the following criteria :
Two or more consecutive prior second trimester pregnancy losses or three or more early (<34 weeks) preterm births.
Risk factors for cervical insufficiency (history of cervical trauma and/or short labors or progressively earlier deliveries in successive pregnancies).
Other causes of preterm birth (Infection, Placental bleeding, Multiple gestation) have been excluded. We also treat these women with 17-alpha-hydroxyprogesterone caproate weekly from 16 to 36 weeks of gestation .
Although randomized trials support the benefit of history-indicated cerclage ,and the benefit of progesterone supplementation in this population, no trials have evaluated the efficacy of combination therapy (both history-indicated cerclage and 17 alpha hydroxy-progesterone caproate)
Con…
Candidates for ultrasound surveillance and possible ultrasound indicated cerclage : The majority of women with suspected cervical insufficiency do not meet the above criteria for history-indicated cerclage.
For these women, we usually initiate TVU cervical length screening, administer 17-alpha-hydroxyprogesterone caproate prophylaxis, and apply a cerclage if cervical length decreases to <25 mm .
Women with a short cervix on TVU are at increased risk of spontaneous preterm birth. In women with a history of spontaneous preterm birth, a systematic review of controlled studies showed that measurement of cervical length in the second trimester, especially before 24 weeks, predicted the risk of recurrent preterm birth .(The use of a TVU cervical length <25 mm at <24 weeks predicts preterm birth at <35 weeks ) and lowers perinatal mortality and morbidity. Protocol for cervical length screening
Approach to transvaginal ultrasound (TVU) measurement of cervical length for screening singleton gestations
Past pregnancy history TVU cervical length screening Frequency
Prior preterm birth 14 to 27 Start at 14 weeks and end at 24 weeks Every 2 weeks as long as weeks cervix is at least 30 mm*
Prior preterm birth 28 to 36 Start at 16 weeks and end at 24 weeks Every 2 weeks as long as weeks cervix is at least 30 mm*
• No prior preterm birth One exam between 18 and 24 weeks Once
* Increase frequency to weekly in women with TVU cervical length of 25 to 29 mm. If <25 mm before 24 weeks, consider cerclage. • If ≤20 mm before 25 weeks, consider progesterone supplementation.
Management of women with previous preterm delivery or second trimester loss
Patient population Interventions to be considered Options in next pregnancy if history- indicated cerclage was not successful (preterm birth <33 weeks)
Women with: Transvaginal cerclage at 12 to 14 weeks, Transabdominal cerclage ≥2 consecutive prior second trimester losses*, 17-alpha-hydroxyprogesterone caproate 17-alpha-hydroxyprogesterone caproate or 250 mg IM weekly from 16 to 36 weeks 250 mg IM weekly from 16 to 36 weeks
≥3 early (<34 weeks) preterm births
Women with: 17-alpha-hydroxyprogesterone caproate One prior second trimester loss*, 250 mg IM weekly from 16 to 36 weeks
Or Serial measurement of cervical length beginning at 14 to 16 weeks and ending at 24 One or two preterm births <37 weeks weeks
If cervical length <25 mm before 24 weeks, place transvaginal cerclage
*Usually a spontaneous pregnancy loss between 16 and 27 6/7ths weeks of gestation. Con…
Women with singleton pregnancy, no prior birth, but risk factors for cervical insufficiency :
Studies of women with risk factors for cervical insufficiency, such as uterine anomaly, prior minor cervical surgery, or pregnancy termination, observed a correlation between risk of preterm birth and short cervical length, but data are limited.
We perform a single TVU cervical length measurement at 18 to 24 weeks in women with risk factors for cervical insufficiency and no prior delivery ,and treat those with a short cervix (≤20 mm) with vaginal progesterone supplementation . In a meta-analysis of five trials, administration of vaginal progesterone to women with a short cervix reduced the rate of spontaneous preterm birth and composite neonatal morbidity and mortality ,and it appears to be cost-effective . If the patient delivers preterm, subsequent pregnancies are managed as described above .
If she delivers at term, we again perform a single cervical length measurement at 18 to 24 weeks and give vaginal progesterone if the cervix is short.
Physical examination reveals a dilated cervix and visible membranes before 24 weeks : Rarely, a woman presents before 24 weeks with minimal or no symptoms and physical examination reveals a dilated cervix. Occasionally, such findings follow the identification of a very short cervical length <5 mm on TVU. In the absence of indications for delivery (such as overt infection, ruptured membranes, or significant hemorrhage), the gestational age and degree of cervical dilation are the next considerations. Prior to viability, management is aimed at prolonging the pregnancy, After viability, the goal is to both prolong the pregnancy and improve neonatal outcome in the likely event of preterm birth. Placement of a physical exam-indicated cerclage when a dilated cervix and visible membranes are detected on digital examination at <24 weeks(in the absence of infection, labor, and vaginal bleeding) appeared to prolong pregnancy and improve pregnancy outcome compared to expectant management.
In women without clinical signs of infection, we offer amniocentesis to check for subclinical infection when the cervix is ≥2 cm and on a case-by-case basis when there are ultrasound findings suggestive of inflammation: membrane edema, separation of membranes from the decidua, or debris in the amniotic fluid (“sludge”)
Prior successful outcome after cerclage :
Prolongation of pregnancy after cerclage does not prove a diagnosis of cervical insufficiency .
In randomized trials and controlled studies, about 60 percent of women with a history of early preterm birth or recurrent late miscarriage maintain cervical length above 25 mm and have low rates of recurrent preterm birth/loss without placement of a cerclage.
Therefore, repeat cerclage in subsequent pregnancies is not mandatory.
In women who received a cerclage in a prior pregnancy without an appropriate indication, especially those who, after removal of cerclage at 36 to 37 weeks, did not go into labor in the subsequent two weeks, the risk of preterm birth in a subsequent pregnancy probably does not warrant a history-indicated cerclage; instead we suggest TVU cervical length screening .
Prior unsuccessful outcome after cerclage :
Transabdominal cerclage may be successful in women who deliver very preterm despite placement of a transvaginal cerclage. No more preterm babies, It is time to act