Measurement of angle of progression by trans perineal-ultrasound in labour to predict mode of delivery in nulliparous women.

Objective: The objective of the study was to assess whether the measurement of the angle of progression in nulliparous women in labour can predict the mode of delivery.

Methods: This prospective observational study was conducted at Benazir Bhutto Hospital, Rawalpindi Medical University from 16^th February to 25^th March 2024. Nulliparous pregnant women in the active first stage of labour with singleton pregnancy and cephalic presentation were included in the study after taking informed consent. The angle of progression (AOP) was measured by trans-perineal ultrasound using the curvilinear probe. The primary outcome was the mode of delivery in relation to angle of progression.

Results: Seventy-eight patients were included in the study. Angle of progression was wider in patients who underwent vaginal delivery and narrower in patients who underwent cesarean section. AOP of 121 or more is associated with 86.6% of vaginal delivery and an angle of progression of 70 or less is associated with 83.3% of cesarean section.

Conclusion: The angle of progression is a reliable tool for predicting the mode of delivery. Wider angle is associated with vaginal delivery and a narrower angle is associated with cesarean section.