[Efficacy of cervical cerclage in singleton pregnancies with short cervix and stratified analysis of cervical length: a retrospective matched cohort study].

Objective: To investigate the clinical efficacy of cervical cerclage in singleton pregnancy with different degrees of short cervix. Methods: The clinical data of singleton pregnant women who underwent transvaginal ultrasound examination at 18-24+6 weeks of gestation and found cervical dilation with cervical length (CL) ≤20 mm, and without history of spontaneous preterm delivery or late abortion in Women's Hospital, Zhejiang University School of Medicine from January 2021 to September 2023 were collected and retrospectively analyzed. According to the case control matching, 78 pregnant women in the cerclage group and 78 women in the conservative treatment group were finally included. The pregnancy outcomes and neonatal prognosis of the two groups were compared. Meanwhile, the two groups of pregnant women were divided into three subgroups for stratification (CL≤10, 11-15, 16-20 mm). Multivariate logistic regression analysis and Kaplan-Meier curve were used to evaluate the effect of cervical cerclage on pregnancy outcomes in different subgroups. Results: (1) Compared with the conservative treatment group, the gestational age at delivery (median: 36 vs 37 weeks) and the duration of pregnancy extension (median: 90 vs 97 days) in the cerclage group were not significantly prolonged (all P>0.05). There was no significant difference in the cumulative non-delivery rate between the cerclage group and the conservative treatment group (P=0.143). The rate of neonatal intensive care unit (NICU) admission in the cerclage group was significantly higher than that in the conservative treatment group (46.1% vs 31.2%, P<0.001), but there were no significant differences in other neonatal outcomes between the two groups (all P>0.05). (2) CL 16-20 mm subgroup: compared with the conservative treatment group (28 cases), the cerclage group (18 cases) had a significantly higher rate of preterm birth before 37 weeks of gestation (3.6% vs 6/18, P<0.001) and a significantly lower neonatal birth weight (median: 3 370 vs 2 925 g, P<0.001). There was no significant difference in the cumulative non-delivery rate between the cerclage group and the conservative treatment group (P=0.168). (3) CL 11-15 mm subgroup: compared with the conservative treatment group (26 cases), the gestational age of delivery in the cerclage group (32 cases) was later (median: 36 and 37 weeks, respectively), and the difference was statistically significant (P<0.05). The cumulative non-delivery rate in the cerclage group was significantly higher than that in the conservative treatment group (P=0.001). (4) CL≤10 mm subgroup: compared with the conservative treatment group (24 cases), the pregnant women in the cerclage group (28 cases) had a later gestational age at delivery (median: 34 vs 37 weeks), a longer duration of pregnancy (median: 74 vs 97 days), and a larger newborn birth weight (median: 2 300 vs 3 165 g). The rates of preterm birth before 34 weeks of gestation (45.8% vs 14.3%) and before 37 weeks of gestation (83.3% vs 39.3%) were lower, and the differences were all statistically significant (all P<0.05). The cumulative non-delivery rate of pregnant women in the cerclage group was significantly higher than that in the conservative treatment group (P<0.001). Conclusion: Cervical cerclage could significantly prolong the gestational weeks and improve the perinatal outcomes for singleton pregnant women with cervical internal orifice dilation and CL≤15 mm without a history of spontaneous preterm delivery or late abortion.