Levator ani abnormality 6 weeks after delivery persists at 6 months.

Objective: Assess postpartum changes in the levator ani muscle using magnetic resonance imaging and relate these changes to obstetric events and risk factors associated with pelvic floor dysfunction.

Study Design: A board-certified radiologist specializing in abdominal imaging evaluated 146 pelvic magnetic resonance studies from 57 primiparous women 6 weeks and 6 months after first obstetric delivery and 32 nulliparous women. A yes/no determination of muscle body and insertion integrity, muscle thinning, and measurement of muscle thickness in millimeters was made for each of 4 muscle sites: right and left puborectalis and right and left ileococcygeous.