Prediction of spontaneous onset of labor at term: the role of cervical length measurement and funneling of internal cervical os detected by transvaginal ultrasonography.

The objective of this study was to examine the values of the cervical length measurement and detection of internal cervical os funneling by transvaginal ultrasonography in the prediction of spontaneous labor within a 7-day period at term. Ninety-three pregnant women were enrolled into this study. All patients were evaluated by transvaginal ultrasonography first at the 37th completed week of gestation and weekly thereafter. Endocervical canal length was measured and the presence of funneling was recorded. The end points were the percentage of patients with a spontaneous onset of labor in the week after these data were recorded. The optimal cutoff values for predicting the onset of spontaneous labor within 7 days were 29.5 mm for cervical length at 37 weeks, 27.5 mm at 38 weeks, 25.5 mm at 39 weeks, and 24.5 mm at 40 weeks of gestation. There was also statistically significant agreement between the presence of the funneling and spontaneous labor within 7 days. Measurement of cervical length and detection of funneling at the internal cervical os by transvaginal ultrasonography might help us to predict the spontaneous onset of labor in a 7-day period, and help clinicians to decide about the time of labor induction in certain complicated pregnancies.