Cerclage in singleton gestations with an extremely short cervix (≤10 mm) and no history of spontaneous preterm birth

BACKGROUND: Data regarding the efficacy of a cervical cerclage for preterm birth prevention in patients with a short cervix and no history of spontaneous preterm birth are limited and inconclusive. OBJECTIVE: This study aimed to determine whether cervical cerclage is associated with an increased time interval to delivery in asymptomatic patients with singleton pregnancies with an extremely short cervical length (<= 10 mm) and no history of spontaneous preterm birth. STUDY DESIGN: This was a multicenter retrospective cohort study of asymptomatic patients with singleton pregnancies with a cervical length of <= 10 mm between 16 and 23 weeks' gestation from January 2014 to December 2019. Patients with previous spontaneous preterm birth, symptoms of preterm labor, cervical dilation of >1 cm, pessary, major fetal structural malformations, or missing data were excluded from the study. The primary outcome of time interval from diagnosis to delivery was compared between those who had a cervical cerclage after diagnosis and those who did not. The secondary outcomes included gestational age at delivery and adverse neonatal outcomes. Moreover, a subgroup analysis of all outcomes in patients already being treated with vaginal progesterone in each group was performed. Statistical analysis included chi-square and Wilcoxon rank-sum tests and a multivariate Cox proportional hazard regression for time interval to delivery. RESULTS: Of the 90 patients included in the study, 52 (57.8%) had cervical cerclage, of which 35 (67.3%) were already being treated with progesterone. Moreover, 38 patients (42.2%) did not have cervical cerclage, of which 21 (55.3%) were already being treated with progesterone. Patients in the cervical cerclage group had an earlier gestational age (21.0 vs 22.0 weeks' gestation; P <=.001) and shorter cervical length (5 vs 7 mm; P=.002) at the diagnosis of a short cervix (cervical length <= 10 mm) than those who did not have a cerclage. Cervical cerclage was associated with a longer time interval to delivery (17.0 vs 15.0 weeks; P=.02) and lower hazard of earlier delivery after diagnosis (adjusted hazard ratio, 0.61; 95% confidence interval, 0.38 -0.99; P=.04) than no cerclage, after accounting for gestational age and cervical length at diagnosis. In patients already treated with progesterone, cervical cerclage was also associated with a longer time interval to delivery (17.0 vs 13.1 weeks; P=.01) and a lower hazard of earlier delivery after diagnosis (adjusted hazard ratio, 0.49; 95% confidence interval, 0.27-0.87; P=.02) compared to those with no cerclage. Late preterm birth was less common in patients with a cervical cerclage compared with those with no cervical cerclage (11.5% vs 31.6%; P=.03). CONCLUSION: Cervical cerclage should be considered in asymptomatic patients with an extremely short cervical length (<= 10 mm) and no history of spontaneous preterm birth.