The effect of levator avulsion on hiatal dimension and function

Objective: Pelvic floor trauma as a result of vaginal childbirth can cause significant pelvic floor morbidity. In this observational study, we intended to define whether such trauma is associated with abnormal hiatal biometry and/or abnormal biomechanical properties of the levator muscle. Study Design: The datasets of 414 urogynecologic patients were assessed in a retrospective study. Patients underwent an interview, clinical examination, and 3-/4-dimensional pelvic floor ultrasound. All analysis was performed offline using proprietary software. Hiatal dimensions and strain were measured. Results: In 21.1% of parous women with a history of vaginal delivery, an avulsion of the levator muscle was diagnosed, and in 8.6% it was bilateral. The relative risk of abnormal distensibility was 3.5 (95% confidence interval, 1.7-6.5) in unilateral and 3.96 (95% confidence interval, 1.7-9.2) in bilateral avulsion. Avulsion increased muscle distensibility on Valsalva and reduced muscle shortening on pelvic floor muscle contraction. Conclusion: Avulsion injury is associated with abnormal levator biometry and function.