Cervical Cerclage for Preventing Spontaneous Preterm Birth in Singleton Pregnancies Without Prior Spontaneous Preterm Birth and With Short Transvaginal Ultrasound Cervical Length

Spontaneous preterm birth (SPTB) remains the number one cause of perinatal mortality in many countries, including the United States. In singleton gestations a short cervical length (CL) on transvaginal ultrasound (TVU) has been shown to be a good predictor of SPTB. Different strategies have been adopted for prevention of SPTB. Growing interest has focused on pessary for prevention of SPTB. Cervical pessary is relatively non-invasive, easy to use, does not require anesthesia, can be used in an outpatient clinic setting, and it is easily removed when necessary. However, a recent systematic review and meta-analysis of randomized clinical trials showed that in singleton pregnancies with short cervix, prophylactic use of the pessary did not reduce the rate of spontaneous preterm delivery or improve perinatal outcome. The evidence supports the use of vaginal progesterone in singleton pregnancies with short cervix, while cervical cerclage seems to be beneficial only in the subgroup of women with both prior SPTB and TVU CL ≤25mm. Interestingly, only 235 singletons without prior SPTB,7 and 504 singletons gestations with prior SPTB,6 have been included in randomized studies on cerclage for TVU CL ≤25mm. A meta-analysis of four trials showed that cervical cerclage did not prevent SPTB in women with short TVU CL and without prior preterm birth.7 However, even if the statistical significance were not reached, they found a reduction in SPTB \<35 weeks by 16% in singletons with short TVU CL and without prior SPTB (20.6% vs 31.2%; relative risk (RR) 0.84, 95% confidence interval (CI) 0.60 to 1.17) and by 24% in singletons without risk factors for SPTB (25.6% vs 33.3%; RR 0.76, 95% CI 0.52 to 1.15). Therefore, the aim of this study is to evaluate the efficacy of cervical cerclage in prevention of SPTB in singleton pregnancies with short TVU CL in second trimester, without prior SPTB.