(492) Can the angle of progression during a prolonged second stage increase the vaginal delivery rate?

The revised 2014 definition by the American College of Obstetricians and Gynecologists allows women to push during the second stage of labor as long as there is observable labor progress. Studies proposed using intrapartum ultrasound during the second stage, particularly the angle of progression (AOP) at rest, as an objective tool to monitor fetal head descent. This study aimed to assess the impact of AOP measurement to monitor fetal head descent on the delivery mode and maternal and neonatal morbidity in women with a second stage of labor of at least 4 hours.

Study Design:

This retrospective study included primiparous women with a prolonged second stage of labor of ≥4 hours who delivered in our labor ward. The study group that included women who delivered between 2017 and 2020 and had a documented AOP measurement at 3:30-4:30 hours from complete dilatation was compared to a control group comprised of women delivering between 2010 and 2014 (before AOP was routinely used in our labor ward). The delivery mode and the maternal and neonatal outcomes were compared between the two groups.

Results:

The demographic characteristics were comparable between the study (n=126) and the control (n=134) groups (Table 1). The second stage was longer, and the spontaneous vaginal delivery (VD) rate was higher in the study compared to the control group (268±21 vs. 249±21 min., p< 0.001 and 14% vs. 3%, p=0.001, respectively). Although not statistically significant, there was a trend towards lower rates of cesarean delivery and failed vacuum extraction (VE) in the study group (24% vs. 33%, p=0.08, 1.5% vs. 5%, p</span>=0.1, respectively). No other significant differences were noted in maternal and neonatal outcomes. One case of neonatal death occurred in the control group.

Conclusion:

In primiparous women with a second stage of labor of ≥4 hours, measurement of the AOP was associated with a longer second stage, a higher rate of spontaneous VD, and a trend toward a lower rate of failed VE attempts without compromising maternal or neonatal outcomes. Further prospective randomized trials are needed to validate our findings.