Predictors of preterm birth following emergency and ultrasound-indicated cervical cerclage: A retrospective study on 136 singleton pregnancies.

Objective: We aimed to retrospectively evaluate obstetric and neonatal outcomes in patients who underwent ultrasound-indicated and rescue cervical cerclage and to identify predictors for cerclage failure and consequent preterm birth (PTB).

Materials And Methods: We conducted a retrospective analysis on singleton pregnancies between 16 and 27 weeks of gestation who presented with a transvaginal sonographic cervical length (TVS-CL) <25 mm and a previous PTB/second-trimester miscarriage or prolapsed amniotic membranes and/or a TVS-CL <15 mm and underwent cervical cerclage at Mangiagalli Center, Milan, between September 2011 and December 2021. Univariate and multivariate logistic regression analyses were used to identify possible predictive factors of cerclage failure.

Results: During the study period, a total of 136 singletons met the inclusion criteria. Overall, 3 % of pregnancies did not reach fetal viability, mostly due to post-cerclage preterm premature rupture of membranes and/or chorioamnionitis. The mean gestational age at delivery was 35.9 ± 4.5 weeks. Neonates were delivered beyond 37 weeks in 63.2 % of cases, between 28 and 37 weeks in 26.5 %, and less than 28 gestational weeks in 10.3 %. At the multivariate analysis, independent risk factors for miscarriage or PTB were cervical length <10 mm (odds ratio, OR 3.44), advanced cervical dilatation (OR 4.76), and in vitro fertilization (OR 4.66). A history of previous miscarriage, premature delivery, and uterine malformations did not increase the risk of post-cerclage delivery before 37 weeks. In the preterm delivery group, 14 % of patients experienced preterm premature rupture of membranes (pPROM) and 10 % had chorioamnionitis, while no case was registered in the term delivery group. A positive vaginal swab at the time of cervical cerclage was not significantly associated with PTB at the multivariate analysis but it emerged as a significant risk factor for both chorioamnionitis (OR 11.03) and pPROM (OR 5.28).

Conclusions: Ultrasound-indicated and rescue cervical cerclage were effective in prolonging pregnancy, even when placed beyond 24 weeks of gestation. Preoperative cervical length of less than 10 mm, advanced dilatation, and in vitro fertilization are associated with an increased risk of cerclage failure. A positive vaginal swab before cerclage is associated with increased rates of intrauterine infectious-inflammatory processes.