First-trimester ultrasound measurements are predictors of early abortion. Risk assessment tables based on combinations of abnormal measures might improve prediction rates.

Objectives: To assess the role of mid-trimester transvaginal sonographic assessment of cervix in predicting the risk of primary cesarean section. Methods: Hundred pregnant women, who attended out-patient department of Tata Main Hospital for ante natal examination, from 1 st December 2011 to 1 st December 2012, were taken up for the study. Only those who had confirmed dates were included in the study. Transvaginal sonography was done at 18 -26 week to measure cervical length. Parameters studied were gestational age at delivery, whether spontaneous or induced, duration of labor, pregnancy outcome and mode of delivery and indication for cesarean section. Results: Majority of LSCS were in the group with cervical length ≥4 cm (57.1%) with "p" value of <0.0001. Only 13.8% women who had vaginal delivery had cervical length ≥4 cm. Out of the 32 women with cervical length ≥4 cm, 26 (81.3%) required induction of labor and 10 (31.3%) delivered after 40 weeks. Mean cervical length for spontaneous onset of labor was 3.11 ± 0.85 cm and for induction of labor was 4.36 ± 1.11 cm ("p" value ≤ 0.001). Multiple logistic regression analysis was performed to study outcome variable of mode of delivery. Cervical length and induction to delivery interval were found to be independent predictor of mode of delivery. In the receiver operating characteristic (ROC) curve analysis, the best cut-off point for prediction of primary cesarean section was 40 mm for cervical length. Sensitivity, specificity, positive predictive value and negative predictive value of cervical length as a predictor of mode of delivery was 54.8%, 91.4%, 82.1% and 73.6% respectively. R 2 (coefficient of determination) was 0.271. Conclusion: Transvaginal cervical length measurement at mid trimester can be used as a predictive tool to determine the risk of primary cesarean section as well as the need of induction of labor.* Capsule: This study assesses the efficacy of transvaginal ultrasound measurement of cervical length as predictor of primary caesarean section. # Corresponding author. M. R. Datta et al.856