Prolonged Second Stage of Labor and Levator Ani Muscle Injuries

OBJECTIVE To determine the effect of pregnancy and vaginal delivery on the pelvic floor and levatorani morphology and function. METHODS Design. Cross-sectional study. Setting. Tertiary care teaching hospital. Population. 75 primigravid women were recruited for assessment at 6 weeks postpartum compared with 25 nulliparous women. Hiatal morphology and levator ani muscle avulsion were assessed by 4-dimensional translabial ultrasound examination. The volume achievement obtained by ultrasound was performed in supine position with empty bladder at rest, on maximum Valsalva maneuver, and on maximum pelvic floor muscle contraction. Main Outcome Measures. Hiatal diameter and area were measured at the plane of minimal hiatal dimension as defined in the midsagittal plane and Levator avulsion was assessed. RESULTS There were significant differences in hiatal area morphology at rest, on Valsalva maneuver and during contraction of muscles among the study groups, but there was no difference in pelvic diameter at rest, on Valsalva maneuver, and during contraction. There were 21 cases of puborectalis avulsion (42%) with no significant difference between non-progressive labor (8 cases) and Normal Vaginal Delivery (NVD) (13 cases) groups. CONCLUSIONS The results of the present study showed that non-progressive labor is the main risk factor for pelvic muscle injuries, indicating the necessity of a better management and timely cesareans in women with prolonged second stage of labor.