Transvaginal sonographic cervical length for the prediction of spontaneous preterm birth in twin pregnancies: a systematic review and metaanalysis

OBJECTIVE: To assess the accuracy of transvaginal sonographic cervical length (CL) in predicting spontaneous preterm birth in women with twin pregnancies. STUDY DESIGN: Systematic review and metaanalysis of predictive test accuracy. RESULTS: Twenty-one studies (16 in asymptomatic women and 5 in symptomatic women) with a total of 3523 women met the inclusion criteria. Among asymptomatic women, a CL <= 20 mm at 20-24 weeks' gestation was the most accurate in predicting preterm birth <32 and <34 weeks' gestation (pooled sensitivities, specificities, and positive and negative likelihood ratios of 39% and 29%, 96% and 97%, 10.1 and 9.0, and 0.64 and 0.74, respectively). A CL <= 25 mm at 20-24 weeks' gestation had a pooled positive likelihood ratio of 9.6 to predict preterm birth <28 weeks' gestation. The predictive accuracy of CL for preterm birth was low in symptomatic women. CONCLUSION: Transvaginal sonographic CL at 20-24 weeks' gestation is a good predictor of spontaneous preterm birth in asymptomatic women with twin pregnancies.