Transvaginal ultrasonographic measurement of cervical length as a predictor of preterm birth: a systematic review with meta-analysis.

The advent of effective interventions to prevent preterm delivery such as 17 hydroxyprogesterone and cerclage serve as an impetus to determine whether routine second trimester transvaginal cervical length screening can identify which women would benefit from these therapies. A systematic review was conducted, 957 abstracts were screened, 234 articles underwent full-text review, and 23 studies were included in the final analysis including 26,792 women. Data from relevant studies were pooled to produce summary estimates of sensitivity, specificity, and likelihood ratios using a random effects model. The ideal criteria of transvaginal cervical length measurements to predict preterm delivery are discussed.