Urethral closure pressures among primiparous women with and without levator ani muscle defects

Vaginal birth is an established risk factor for levator ani (LA) defects and incontinence. We hypothesized an association between urethral pressure profiles and LA defects.

One hundred sixty primiparous women, 9-12 months postpartum, were assessed with MRI for LA defects, urodynamic testing, and instrumented speculum for vaginal closure force. Urodynamic testing included resting maximal urethral closure pressure (MUCP) and urethral closure pressure with a pelvic floor contraction or Kegel (KUCP). We examined the relationships between MUCP, KUCP, LA defect status, and vaginal closure force.

There was no significant association between MUCP or KUCP in women with and without LA defects (p = 0.94, p = 0.95). Additionally, there was no correlation between MUCP and vaginal closure force (r = 0.06, p = 0.41), and a weak correlation between KUCP and vaginal closure force (r = 0.20, p = 0.01).

In this population, urethral pressure profiles are unrelated to LA defect status after vaginal birth, indicating that the mechanism responsible for LA damage spares the urethra.