Role of transvaginal sonographic cervical length in predicting spontaneous preterm delivery in triplet pregnancies with therapeutic cerclage

OBJECTIVE: To assess the role of transvaginal sonographic cervical length in predicting spontaneous preterm delivery at <32 weeks in patients with both triplet pregnancy and therapeutic cerclage. STUDY DESIGN: The maternal records of all triplet pregnancies with therapeutic cerclage and sonographic cervical length before and after cerclage were reviewed (n = 17). Each of these triplet gestations was matched with 2 triplet pregnancies without cerclage based on cervical length after cerclage (+/-0.5 cm) and gestational age (+/-3 weeks). Statistical analysis included Fisher's exact test or chi(2) analysis, one-way analysis of variance, logistic regression analysis and receiver operating characteristic curve analysis. RESULTS: Cerclage was placed at a gestational age of 19.0 +/- 3.1 weeks (mean +/- SD) and increased cervical length from 2.0 +/- 0.7 cm to 3.1 +/- 1.4 cm (P < .05). The rate of spontaneous preterm delivery at <32 weeks was higher among cases than controls (7/17 vs. 4/27, P = .08). Logistic regression analysis demonstrated that only postcerclage cervical length was predictive of spontaneous preterm delivery at <32 weeks, with a cervical length of 3.3 cm the optimal predictor. CONCLUSION: In women with triplets and therapeutic cerclage, the only significant predictor of spontaneous preterm delivery at <32 weeks is cervical length after cerclage placement.