Combination of tomographic ultrasound imaging and three-dimensional magnetic resonance imaging-based model to diagnose postpartum levator avulsion

Vaginal delivery may cause levator avulsion, which may increase the risk of pelvic floor dysfunction (PFD). To explore the morphological changes of the levator ani muscle (including the puborectalis and iliococcygeus) and levator avulsion after vaginal delivery, translabial tomographic ultrasound imaging (TUI) was used to examine 80 women 45–60 days after their vaginal delivery. Subsequently, magnetic resonance imaging (MRI) was performed if at least one-sided puborectalis avulsion was found on TUI. The incidence of puborectalis avulsion in these postpartum women was 13.75% in this study. Both MRI and TUI can detect puborectalis avulsion well, and their results have good consistency. Iliococcygeus muscle injury is difficult to detect using TUI. However, MRI is a good way to observe the morphological changes of the iliococcygeus, which may also be damaged during vaginal delivery. Interestingly, our study reveals that iliococcygeus muscle injury is often associated with severe puborectalis muscle tear.