Levator Ani Muscle Avulsion After Soft Cup Vacuum-Assisted Versus Spontaneous Vaginal Delivery: A 3D Transperineal Ultrasound Study.

INTRODUCTION AND HYPOTHESIS: Operative vaginal delivery is associated with an increased risk of levator ani muscle (LAM) injury. We aimed to compare LAM avulsion and pelvic floor morphology after soft cup vacuum-assisted versus spontaneous vaginal delivery using 3-dimensional transperineal ultrasound (3D-TPUS) and hypothesized that soft cup vacuum-assisted delivery would not increase LAM avulsion rates.

METHODS

In this prospective case-control study, nulliparous women who delivered at a tertiary center between January 2023 and December 2025 were included. Women undergoing soft cup-vacuum assisted vaginal delivery were compared with those having spontaneous vaginal delivery. At 6-8 weeks postpartum, participants underwent 3D-TPUS assessment. LAM avulsion, levator-urethra gap (LUG), hiatal dimensions, ballooning, and loss of tenting were evaluated. Functional outcomes were also assessed.

RESULTS

A total of 77 women were analyzed (soft cup n = 36; control n = 41). Complete avulsion was more frequent in the soft cup group (25.0% vs. 9.7%), although this did not reach statistical significance (p = 0.126). Hiatal dimensions, LUG measurements, ballooning, and tenting loss were comparable between groups. Functional outcomes did not differ significantly. Episiotomy rates were higher in the soft cup group (91.7% vs. 53.7%, p < 0.001). Neonatal scalp complications were more frequent following soft vacuum cup-assisted delivery (36.1% vs. 12.2%, p = 0.017), whereas neonatal intensive care unit admissions were similar.

CONCLUSIONS

Soft cup vacuum-assisted vaginal delivery was not associated with a statistically significant increase in LAM avulsion compared with spontaneous vaginal delivery. Despite higher rates of minor neonatal scalp complications, pelvic floor morphology and functional outcomes were comparable between groups.