Intrapartum ultrasound use in clinical practice as a predictor of delivery mode during prolonged second stage of labor

Abstract

Purpose To determine the validity of Intrapartum ultrasound (IPUS), and particularly the angle of progression (AOP), in predicting delivery mode when measured in real-life clinical practice among women with protracted second stages of labor. Methods Using electronic medical records, nulliparous women with a second stage of labor of ≥ 3hours ("prolonged") and a documented AOP measurement during the second stage were identified. The ability of a single AOP measurement in "prolonged" second stage to predict a vaginal delivery (VD) was assessed. Fetal head descend, measured by AOP change/hour (calculated from serial measurements) was compared between women who delivered vaginally and those who had a cesarean delivery (CD) for arrest of descent. Results Of the 191 women who met the inclusion criteria, 62 (32.5%) delivered spontaneously, 96 (50.2%) had a vacuum extraction (VE) and 33 (17.3%) had a CD. The mean AOP was wider among women who had VD (spontaneous or VE) compared to those who had CD (153º±19 vs. 133º±17, p < 0.001). Wider AOPs were associated with higher rates of VD and an AOP ≥ 127º was associated with a VD rate of 88.6% (148/167). Among the 87 women who had more than one AOP measurement, the mean AOP change per hour was higher in the VD group than in the CD group (15.1º±11.4º vs. 6.2º±6.3º, p < 0.001). Conclusion Ultrasound assessed fetal head station in nulliparous women with a protracted second stage of labor can be an accurate and objective additive tool in predicting mode and interval time to delivery in real-life clinical practice.