The value of ultrasonographic examination of the uterine cervix in predicting post-term pregnancy

Object: To assess whether transvaginal ultrasound is helpful in predicting the post-term onset of labor (greater than or equal to1 weeks). Setting: Antenatal clinic of a University hospital and referral center. Subject and mehods: One hundred and twenty singleton uncomplicated pregnanc ies in primiparous women were enrolled at 37 weeks of gestation. Ultrasound examination of the cervical length by a transvaginal probe was performed a t recruitment and at weekly intervals until 40 completed weeks. Subjects we re divided into Group A (those with spontaneous onset of labor less than or equal to 1 completed weeks) and Group B (those not in labor by that date). Results: Eighty women delivered less than or equal to 41 completed weeks, f orty were not in labor by that date. The cervix was significantly shorter a t 39 and 40 weeks in group A, but no particular cervical length was predict ive of post-term delivery. Discussion: There is a significant difference in cervical length in women d elivering at term compared with those due to have a post-term delivery. Thi s difference is significant from 39 weeks of gestation onwards. We speculat e that targeted transvaginal ultrasound may be useful in predicting the pos t-term onset of labor and possibly in assisting its active management.