Ultrasonographic Evaluation of the Second Stage of Labor according to the Mode of Delivery: A Prospective Study in Greece.

Background And Objectives: Accurate diagnosis of labor progress is crucial for making well-informed decisions regarding timely and appropriate interventions to optimize outcomes for both the mother and the fetus. The aim of this study was to assess the progress of the second stage of labor using intrapartum ultrasound.

Material And Methods: This was a prospective study (December 2022-December 2023) conducted at the Third Department of Obstetrics and Gynecology, School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece. Maternal-fetal and labor characteristics were recorded, and two ultrasound parameters were measured: the angle of progression (AoP) and the head-perineum distance (HPD). The correlation between the two ultrasonographic values and the maternal-fetal characteristics was investigated. Multinomial regression analysis was also conducted to investigate any potential predictors of the mode of delivery.

Results: A total of 82 women at the second stage of labor were clinically and sonographically assessed. The mean duration of the second stage of labor differed between vaginal and cesarean deliveries (65.3 vs. 160 min; -value < 0.001) and between cesarean and operative vaginal deliveries (160 vs. 88.6 min; -value = 0.015). The occiput anterior position was associated with an increased likelihood of vaginal delivery (OR: 24.167; 95% CI: 3.8-152.5; -value < 0.001). No significant differences were identified in the AoP among the three different modes of delivery (vaginal: 145.7° vs. operative vaginal: 139.9° vs. cesarean: 132.1°; -value = 0.289). The mean HPD differed significantly between vaginal and cesarean deliveries (28.6 vs. 41.4 mm; -value < 0.001) and between cesarean and operative vaginal deliveries (41.4 vs. 26.9 mm; -value = 0.002); it was correlated significantly with maternal BMI (r = 0.268; -value = 0.024) and the duration of the second stage of labor (r = 0.256; -value = 0.031). Low parity (OR: 12.024; 95% CI: 6.320-22.876; -value < 0.001) and high HPD (OR: 1.23; 95% CI: 1.05-1.43; -value = 0.007) were found to be significant predictors of cesarean delivery.

Conclusions: The use of intrapartum ultrasound as an adjunctive technique to the standard clinical evaluation may enhance the diagnostic approach to an abnormal labor progress and predict the need for operative vaginal or cesarean delivery.