[Ultrasonographic and clinical methods in the management of prolonged pregnancy]

The aim of this study was to evaluate the role of Bishop score, sonographic measurements of uterine cervical length and maternal characteristics, as predictors of spontaneous onset of labor within 24 hours, as well as response to induction in prolonged pregnancies.

Pregnancies with gestational age over 280 days were followed as outpatient. Patients were included in the study if spontaneous delivery occurred between 286 and 295 days of gestation, or in pregnancies with gestational age of 291-293 days who required labor induction. Data about Bishop score, ultrasonographic cervical characteristics (length, funneling, volume) and maternal features (parity, body mass index and age) registered at the last control immediately before the delivery were retrieved from clinical charts.

Data from 195 patients were available. Bishop score and, in particular, ultrasonographic cervical length can predict the spontaneous onset of labor with a positive predictive value (PPV) of 22% and 44%, respectively in 24 hours. On the other hands, in patients requiring labor induction, parity and ultrasonographic cervical length remained the only predictive parameters with a PPV of 39% and 42%, respectively. In term of predictive performance, the value of 30 mm was identified as the best cut-off value for the ultrasonographic cervical length (specificity 59% and sensitivity 69%).

In prolonged pregnancies, Bishop score and ultrasonographic cervical length were shown to be relevant in the prediction of spontaneous onset of labor, while in patients who required labor induction, ultrasonographic cervical length represented the only clinic parameter predicting the onset of labor.