RESUMO
OBJECTIVES: We compared the pregnancy prolongation effect attributable to cervical cerclage to that achieved by conservative management, and determined the cervical length for which cervical cerclage is effective. METHODS: We retrospectively examined medical records of 281 women admitted to our hospital between January 2013 and December 2017 for management of threatened preterm birth at 22-28 weeks of gestation. Obstetricians determined suitability for cervical cerclage, which was performed using the McDonald procedure in all cases. Of the 281 subjects, 71 underwent cervical cerclage (cerclage group); the other 210 received conservative therapy (non-cerclage group). We recorded maternal and neonatal characteristics of all patients. The two groups were compared in terms of length of extension of pregnancy and weeks of gestation at delivery. Multivariate analysis was performed to identify factors associated with extension of time to delivery. RESULTS: Our analyses revealed that the cerclage group was hospitalized earlier in pregnancy than the non-cerclage group (23.7 ± 1.5 weeks vs. 26.4 ± 1.9 weeks, p < .001) and had shorter cervixes (6.0 ± 9.4 mm vs. 16.9 ± 13.0 mm, p < .001). The two groups did not differ significantly in terms of gestational weeks at delivery. Multivariate analysis regarding extension of pregnancy revealed significant differences in extension of pregnancy related with cervical cerclage (26.65 days, 95% CI 17.0 - 36.3, p < .001) and cervical length <10 mm (-27.4 days, 95% CI -36.0--18.8, p < .001). While the time to delivery was extended by cervical cerclage in women with short cervixes (<25 mm), the two groups did not differ when cervical length was ≥15 mm. CONCLUSIONS: Cervical cerclage was a significant positive factor and short cervix was a significant negative factor for elongating pregnancy. In primigravida and multigravida women with no history of preterm birth, when the cervix is short (<10 mm), cervical cerclage should be recommended.