Angle of progression as a predictor of success in labor induction in term pregnancies

Abstract

Objective: To establish the utility of the angle of progression as a predictor of the success of labor induction in term pregnancies. Methodology: A prospective, comparative case-control study was conducted at the Central Hospital of Maracaibo between November 2020 and December 2024. Before the induction, all participants underwent cervical ultrasound evaluation to determine the value of the angle of progression. The main variables measured were the type of delivery and the interval between the start of induction and delivery. Results: A total of 443 pregnant women underwent labor induction. There were 349 vaginal deliveries (78.8%) and 94 cesarean deliveries (21.2%). The angle of progression before labor induction was significantly greater in patients who achieved vaginal delivery compared to those who required cesarean delivery (p  < 0.0001). The cutoff value of 94° for the angle of progression in pre-induction showed a high capacity to predict the success of labor induction, with an index of 0.863. This cutoff value exhibited a sensitivity of 72.8%, a specificity of 84.0%, a positive predictive value of 94.4%, and a negative predictive value of 45.4%. The predictive accuracy was 75.2%. Patients with an angle of progression of 94° or more had a shorter interval between induction and delivery than those with an angle of progression less than 93° (p  < 0.0003). Conclusions: The angle of progression is established as a predictor of the success of labor induction in term pregnancies.