Angle of progression with trans-perineal ultrasound and delivery type in labor’s second stage; a cross-sectional study in Isfahan, Iran

Introduction: Numerous studies have shown that clinical evaluation in labor is not very accurate, therefore ultrasound is one of the instruments that can give us a more objective assessment than the clinical evaluation. Objectives: In this study, we investigate the magnitude of the angle of progression (AoP) at the second stage of labor in fetuses with cephalic presentation and its relation to spontaneous vaginal delivery. Patients and Methods: In this cross-sectional study, we measured the AoP using trans-perineal sonography in the 2nd stage of the labor and compared AoP in normal vaginal delivery (NVD), cesarean and NVD with vacuum groups on 80 pregnant women. We also investigated the correlation between AoP and induction time and duration of the second stage of labor. Results: In 80 study patients, 54 (67.5 %) had normal vaginal deliveries, 21 (26.2 %) had cesarean section and 5 (6.2%) had NVD with a vacuum. There was a statistically significant difference between NVD, cesarean section, and NVD with vacuum in terms of the AoP (P<0.01). There was a statistically significant correlation between AoP and induction time, duration of 2nd stage of labor and Apgar scores (P<0.05). Conclusion: Higher progression angle is associated with shorter induction time and 2nd stage of labor, higher neonatal Apgar scores and a higher chance of spontaneous vaginal delivery which makes it an appropriate index for predicting pregnancy outcomes.