Role of intrapartum transperineal ultrasound: Angle of progression cut-off and correlation with delivery mode

Abstract

Objective: The aim of this study was to investigate the role of the 'angle of progression' (AOP) in the prediction of vaginal delivery and establish a cut-off value.Method: 101 pregnant women were included in this prospective study. They were admitted in labor to our hospital and had singleton cephalic presentations and full-term pregnancies. AOP was measured at admission time. We analyzed the results of all the women included but also a subgroup of 66 singleton pregnant women whose assessment of the AOP was performed at the beginning of the second stage of labor.Results: Ninety-one patients had a vaginal delivery (90%) and 19 a cesarean section (10%).The area under the curve was 0.85 (95% confidence interval [CI], 0.77-0.92)and the value of the AOP that optimizes the curve was 125º (S 67.1% E 100%). In the subgroup that was assessed at the second stage of labor, the area under the curve was 0.97 (95%CI,0.90-0.99) and a value of the AOP that optimizes the curve was also 125º (S 91.38% E 100%). Conclusions:The angle of progression is a simple and reliable intrapartum ultrasound parameter for the evaluation of fetal head descent. Transperineal ultrasound assessment could help to decide the method of delivery. In our experience, the sensitivity of the ultrasound measurement increases when this is taken in the second stage of childbirth.

Utility of Ultrasonographic Parameters for Monitoring of Progress of Labor and Prediction of Successful Vaginal Delivery: Narrative Review

“…The cutoff value of AOP that predicted vaginal delivery in both stages was 125°. 29 Angle of progression was measured in the late first and second stages of labor among 500 women in a prospective cohort study. Angle of progression was significantly higher in spontaneous vaginal delivery group (with cutoff 123° ± 8.5°) as compared with women delivered by vacuum or by CS (113° ± 10.5°) (p = 0.003).…”