Post-cerclage ultrasonographic cervical length can predict preterm delivery in elective cervical cerclage patients

OBJECTIVE To evaluate the usefulness of transvaginal ultrasound measurements of cervical length before and after elective prophylactic cervical cerclage in predicting preterm delivery before 32 weeks of gestation. METHODS Women who underwent an elective cerclage operation at 14 to 19 weeks of gestation and who delivered between January 2004 and December 2009 were enrolled in this study (n=52). Ultrasonography was performed to measure cervical length before and after cerclage. The primary outcome was defined as preterm delivery before 32 weeks of gestation. A receiver operating characteristic curve was used to determine the most discriminating cut-off values of ultrasonographic cervical parameters predictive of preterm delivery before 32 weeks of gestation. RESULTS Among the 52 patients studied, ten delivered before 32 weeks of gestation. Among the ultrasonographic cervical parameters compared, only the cervical length after cerclage was significantly different (shorter) in patients who delivered before 32 weeks of gestation (P=0.037) compared to that of those who delivered after 32 weeks of gestation in univariate and multivariate analyses (odds ratio, 0.402; 95% confidence interval, 0.174 to 0.925; P=0.021). The receiver operating characteristic curve showed that a cervical length of 25 mm or less after cerclage was predictive of preterm delivery before 32 weeks of gestation (area under curve, 0.71; 95% confidence interval, 0.56 to 0.87; P=0.029) with a sensitivity of 91.0% and a specificity of 30.0%. CONCLUSION Patients with a cervical length less than 25 mm after elective cerclage may be at higher risk of preterm delivery before 32 weeks of gestation.