The predictive value of transvaginal cervical length and cervical angle ultrasonography in term delivery outcomes: a cohort study.

Background: Various techniques have been proposed to predict and evaluate the timing and conditions of childbirth in pregnant women at different stages of pregnancy. Providing precise methods for forecasting childbirth status can reduce the burden on the healthcare system. This study aimed to evaluate the predictive value of transvaginal sonography of cervical length (CL) and cervical angle (CA) on full-term delivery outcomes.

Methods: This cohort study analyzed 151 pregnant women between 37 and 42 weeks of gestational age who were treated at Rasoul Akram Hospital affiliated with Iran University of Medical Sciences from June 2023 to January 2024. All Participants received transvaginal examinations. This study evaluated the accuracy of CL and CA by transvaginal sonography in predicting outcomes like vaginal delivery, cesarean section, necessity for labor induction, and the rate of Premature Rupture of Membranes (PROM). The study used the Receiver Operating Characteristic (ROC) curve to determine the optimal cutoff for predicting birth outcomes.

Results: The mean age of the pregnant women was 28.9 ± 4.22 years, while the average duration of pregnancy was 39.8 ± 2.11 weeks. Cesarean delivery was performed on 45 individuals (29.8%) and 106 (70.1%) underwent vaginal delivery. The mean CL overall stood at 21.2 ± 6.4 mm. PROM was observed in 41 cases (27.1%) among full-term pregnancies. A significant difference was noted in mean CL between the cesarean and vaginal delivery groups (24.2 ± 2.4 vs. 20.1 ± 2.1 mm, p = 0.001). The predictive value of a CL measuring 21 mm for cesarean delivery was 72.2% sensitive and 79.1% specific. Similarly, a CL of 22 mm showed 66.6% sensitivity and 80.2% specificity for labor induction. Regarding PROM in full-term pregnancies, a CL assessment demonstrated 59.8% sensitivity and 69.1% specificity. Finally, a CA of 115.2° exhibited 70.3% sensitivity and 78.4% specificity in predicting vaginal delivery.

Conclusion: The present study showed that evaluating CL and CA via transvaginal sonography demonstrated adequate diagnostic accuracy in predicting spontaneous birth, need for labor induction, cesarean delivery, and incidence of PROM in full-term pregnant women. This method is suggested to be an accurate and appropriate way to predict delivery results.