Cervical cerclage for preterm birth prevention in twin gestations with short cervix: a retrospective cohort study: Cerclage for twins with short cervix

Objective To determine if cervical cerclage reduces the rate of spontaneous early preterm birth in cases of dichorionic–diamniotic (DCDA) twin gestation with an ultrasound-detected short cervix. Methods This was a retrospective cohort study of 40 consecutive DCDA twin gestations at Saint Peter’s University Hospital from November 2006 to November 2014 in which cervical cerclage was performed for an ultrasound-determined cervical length of 1–24 mm at 16–24 weeks’ gestation. The cases were matched with 40 controls without cerclage for cervical length and gestational age at cervical assessment. The primary outcome measure was spontaneous birth < 32 weeks. Results There was no difference between the two groups in maternal age, body mass index (BMI), cigarette smoking, use of in-vitro fertilization (IVF), parity and prior spontaneous preterm birth. There were more Caucasian women among the controls compared with cases. In the cases, compared with controls, spontaneous delivery < 32 weeks was significantly less frequent (20.0% vs 50.0%; relative risk, 0.40 (95% CI, 0.20–0.80)). In the prediction of spontaneous delivery < 32 weeks, logistic regression analysis demonstrated that the risk was reduced with the insertion of cervical cerclage (odds ratio, 0.22 (95% CI, 0.058–0.835); P= 0.026), corrected for maternal age, BMI, racial origin, cigarette smoking, IVF, parity and previous preterm birth. Conclusion In DCDA twin gestation with a short cervix, treatment with cervical cerclage may reduce the rate of early preterm birth. The findings suggest the need for adequate randomized controlled trials on cerclage in twin gestations with a short cervix. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. Correspondence to: Dr E. R. Guzman, Saint Peter’s University Hospital, Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, MOB 4th Floor, 254 Easton Avenue, New Brunswick, NJ 08901, USA (e-mail: [email protected]) Accepted: 9 March 2016 INTRODUCTION With a prevalence of less than 2% of all pregnancies, twin pregnancies account for more than 25% of spontaneous early preterm births1,2. Strategies for prevention of preterm birth include the use of vaginal progesterone, cervical pessary and cervical cerclage. Individual patient data meta-analyses (IPDMAs) from randomized controlled trials (RCTs) reported that vaginal progesterone in twin gestation with a sonographic short cervix did not significantly reduce the rate of preterm birth <33 weeks, but it reduced the risk of composite neonatal morbidity and mortality3,4. The Arabin pessary has been shown to be effective in reducing early preterm birth in singleton gestations with short cervix and has generated interest in its use in twin gestations5. A RCT in twin gestations found that prophylactic use of the Arabin pessary reduced the rate of early preterm birth, but only in the subgroup with a short cervix6. However, a large multicenter RCT on the use of the Arabin pessary in unselected twin gestations, administered either prophylactically or for those with cervical length ≤ 25 mm, had no effect on spontaneous birth <34 weeks or neonatal outcome7. An IPDMA of RCTs primarily on singletons that included 49 sets of twins found that, in twin gestation with a short cervix, the use of cervical cerclage may double the rate of spontaneous early preterm birth8. These results led to recommendations in the ‘Choosing Wisely’ program (an initiative of the American Board of Internal Medicine aimed at advancing a dialogue on avoiding wasteful or unnecessary medical tests, treatments and procedures) to warn patients against physicians’ recommendations to perform cerclage for a short cervix in twin gestation9. The IPDMA was subsequently repeated, controlling for confounders, and concluded that cerclage did not reduce the incidence of delivery < 34 weeks’ gestation, and its use was associated Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. ORIGINAL PAPER Cerclage for twin gestation with short cervix 753 with an increase in respiratory distress syndrome and a birth weight < 1500 g8,10. However, a recent retrospective cohort study reported that cerclage in twin gestation with short cervix reduced the rate of early preterm birth (n= 57 cerclage vs 83 expectant)11. Our group has routinely screened twin gestations and offered cerclage for a short cervix since the 1990s with encouraging results12. Consequently, we have continued to perform cervical ultrasound screening and offered cervical cerclage for a progressively shortening cervix. The purpose of this retrospective cohort study was to determine whether cerclage in DCDA twin gestations with short cervix reduces the rate of spontaneous preterm birth < 32 weeks’ gestation. PATIENTS AND METHODS This was a retrospective cohort study of DCDA twin gestations with serial vaginal cervical sonography performed in women who were asymptomatic. Excluded cases were monoamniotic and monochorionic–diamniotic twin gestations, those with major fetal defects and women who had placenta previa or complained of contractions or vaginal bleeding, or were found to have signs or symptoms of intra-amniotic infection. Approval was obtained from the institutional review boards of the institutions involved. The study cases included 49 consecutive asymptomatic DCDA twin gestations that were routinely screened with vaginal sonographic cervical length assessments every 2 weeks from 16 to 24 weeks’ gestation at Saint Peter’s University Hospital, New Brunswick, NJ, USA, between November 2006 and November 2014. Nine of these cases with cervical length of 0 mm, a dilated external cervical os and visible membranes were excluded from subsequent case–control matching and statistical analysis. The 40 cases included in the analysis were treated with cervical cerclage for short cervix at 16–24 weeks’ gestation. Cerclage placement was considered when the cervical length was < 25 mm. Cervical lengths of 16–25 mm were considered as intermediately short and additional factors utilized to offer a cerclage included rate of cervical shortening, progressive shortening within this range, history of prior spontaneous preterm birth or mid-trimester loss and gestational age at onset of cervical shortening. A cervical length of ≤ 15 mm was a definitive indicator for offering cerclage. The sonographic cervical length was not used by itself to determine whether to place the cerclage. The technical difficulty is the same regardless of cervical length on ultrasound, including those with zero length, since these cervices are equally thick and long and simply dilate from within. The preoperative evaluation assessed for vaginal bleeding, vaginal discharge, cervical lacerations, intra-amniotic infection and uterine contractions. Speculum examinations were performed with the use of Q-tips to evert the exocervix to look for vaginal–cervical discharge, cervical lacerations and appearance and location of the membranes, if visible. All patients had an evaluation of serum white blood cell (WBC) count and differential. The patient was observed for a period of up to 48 h before surgery if there was any concern of infection, presence of contractions and/or labor. An isolated finding of vaginal discharge was evaluated for a definitive diagnosis and treated for at least 2 days. Evaluation of vaginal discharge included a wet mount microscopic evaluation without cultures. Amniocentesis was considered if there was a clinical/laboratory suspicion of infection or the cervix was dilated with membranes at, or past, the external os. If amniocentesis was indicated it was the last step of the evaluation process and performed within several hours of the cerclage procedure so that the amniocentesis results were a true assessment of intra-amniotic infection at the time of cerclage placement. Evidence of intra-amniotic infection was defined as WBC count >50, glucose level < 15 mg/dL and positive Gram staining for WBCs or bacteria. Cultures were taken but results were not used in decisions regarding cerclage placement. Evidence of intra-amniotic infection was a contraindication for cerclage. During this period of observation, repeat vaginal sonography was sometimes performed to identify any unfavorable change in cervical status. If membranes were beyond the exocervix, membrane tension, ability to reduce membranes digitally and cervical thickness/effacement were assessed by digital examination to determine technical feasibility of cerclage placement. An effaced cervix was considered evidence of labor and a contraindication to cerclage. Those that did not satisfy the criteria for cerclage placement during the period of preoperative evaluation were not offered the procedure. Preoperative prophylactic antibiotics, initially clindamycin and then ceftriaxone, and perioperative indomethacin were administered. The modified McDonald cervical cerclage procedure was performed by one of two operators (C.H. and E.R.G.). In the operating room, a sponge stick was placed in the endocervical canal to determine the location of the membranes and the anterior lip of the cervix was grasped with the sponge stick. A Foley catheter was passed within the endocervical canal and its balloon was inflated with 30 mL of fluid to displace the membranes from the operative site and avoid inadvertent membrane puncture during suture placement. Two pieces of 0 Prolene (Ethicon, Somerville, NJ, USA) were used with a CT needle, with placement begun at the first to second cervical–vaginal rugal folds at 12 o’clock. At our institution, we use Prolene because (1) it is non-reactive and monofilamentous and therefore may be associated with less inflammation and microbial growth within the suture in comparison with other suture materials, and (2) the needles attached to this suture material are of a size that allows the operator better access to the upper areas of the vagina and cervix leading to consistent high cerclage placement. If a cervical laceration was present the sutures had to be placed beyond the apex of the laceration with or without dissection of the cervical–vaginal mucosa. We placed two sutures for added reinforcement and the second suture was placed above the first by 3–10 mm. Before tying the sutures, Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. Ultrasound Obstet Gynecol 2016; 48: 752–756.