Comparison of the Bishop score, sonographic measurement of cervical lengthand fibronectin assay in predicting time to delivery and type of delivery at term

Our aim was to compare the Bishop score, FNf assays, and the sonographic me asurement of cervical length, in order to assess the best marker for time u ntil spontaneous labor at term and risk of cesarean, especially for lack of progress of dilatation. This prospective study included 128 singleton vert ex pregnancies with no clinical evidence of membrane rupture or regular con tractions and a prenatal consultation between 39 weeks 4 days and 40 weeks 3 days. We successively assayed FNf; determine the Bishop scored and measur ed cervical length by transvaginal ultrasound. The endpoints were the perce ntage of patients with a spontaneous onset of labor in the week following t hese tests and the type of delivery. The spontaneous onset of labor within a 7-day period was closely associated with a Bishop score greater than or e qual to 6 and especially with a cervical length less than or equal to 26 mm , but not with a positive FNf On the other hand, vaginal delivery was signi ficantly associated with the fibronectin assay but not,vith either the Bish op score or cervical length. Ultrasound measurement of cervical length and the fetal fibronectin assay provide different physiological data useful for different purposes : cervical length is more valuable than the Bishop scor e for predicting the onset of spontaneous labor within 7 days (when these a ssessments are performed close to term) and the FNf assay is very useful fo r evaluating the risk of cesarean.