Using transperineal ultrasound to predict labor onset

Fanghua Peng, Yang Yu, Yanan Sun, Shan Jiang, Yun Han, Zhikun Zhang


Background: Accurate diagnosis of labor onset is especially important for the counseling about elective induction of labor. The study aimed to evaluate whether transperineal ultrasound could better predict the timing and likelihood of spontaneous labor at term.
Methods: This single-center study was conducted between 2018 and 2019.Data on singleton pregnant women after 39 weeks and before labor onset were retrospectively reviewed.
Results: All the transperineal ultrasound parameters were well reproducible between the two doctors [intraclass correlation coefficient (ICC) for progression distance(PD) was 0.892, P<0.001], [ICC for angle of progression (AoP) was 0.881, P<0.001], [ICC for subpubic arch angle (SPA) was 0.766, P<0.001], [ICC for width of symphysis pubis (WSP) was 0.803, P<0.001]. For the pregnant women before 40 weeks, the width of symphysis pubis changed gradually with the of spontaneous labor (WSP) (r=0.33, P<0.05). For all included women, the SPA correlated with the time of spontaneous labor (SPA) (r=0.31, P<0.05).
Conclusions: The antepartum transperineal ultrasound is a simple and objective technique that better observes the initiation of labor. And with the WSP and SPA we were able to predict labor onset and help in counseling about elective induction of labor.