Vacuum-assisted vaginal delivery and levator ani avulsion in primiparous women

We compared the incidence and type of levator ani avulsion diagnosed by translabial ultrasound evaluation in primiparous women six months after vacuum-assisted or spontaneous vaginal delivery.

This retrospective observational study was performed between January 2011 and December 2013. Primiparous women six months after vacuum-assisted vaginal delivery and after spontaneous vaginal delivery underwent translabial ultrasound evaluation. The distance between the urethra and fibers of the musculus levator ani puborectalis (levator-urethra gap) was measured. A levator-urethra gap >25 mm was considered a musculus levator ani avulsion.

In total, 184 women participated in the study. Among them, 92 had vacuum extraction and 92 had uncomplicated spontaneous delivery. A longer levator-urethra gap on both sides of the pubic bone was found in women after vacuum-assisted vaginal delivery (p < 0.0001 for both sides). Musculus levator ani avulsion was identified in 20 women (unilateral in 16 cases and bilateral in four cases). No difference in an incidence of musculus levator ani avulsion was identified in women after vacuum-assisted vaginal delivery [11/92 (12%)] compared to spontaneous delivery [9/92 (10%); p = 0.81].

Vacuum-assisted vaginal delivery in primiparous women is associated with a longer levator-urethra gap but not with a higher frequency of avulsion of the musculus levator ani.