Levator hematoma at the attachment zone as an early marker for levator ani muscle avulsion

Childbirth causes overstretching of the levator ani muscle (LAM), predisposing to avulsion. LAM avulsion has not been evaluated early postpartum using endovaginal ultrasound (EVUS). The aim of this study was to evaluate the relationship between hematomas and LAM avulsion using EVUS and palpation early and late postpartum.

Nulliparous women were studied prospectively at 36 weeks' gestation and within 4 days and 3 months postpartum. Palpation and high-frequency three-dimensional EVUS were performed. Two independent investigators reviewed the scans.

No antenatal LAM avulsions were found (n = 269). 114/199 (57.3%) women seen early postpartum agreed to examination. 27/114 (23.7%) had well delineated, hypoechoic areas consistent with hematomas (100% agreement), 26 following vaginal delivery, one following emergency Cesarean section. In total, 38 hematomas were found (11 bilateral, 16 unilateral). Hematomas away from the attachment zone of the LAM to the pubic bone (n = 22) resolved. Hematomas at the attachment zone (n = 16) manifested as pubococcygeus avulsions 3 months postpartum. In addition to these 16 avulsions, we found another 20 at 3 months postpartum. 13/20 were not scanned early postpartum and in seven no hematomas were seen, but avulsion was seen early postpartum. Overall, LAM avulsion was found in 23/191 (12.0%) women (13 bilateral, 10 unilateral) 3 months postpartum. Hematomas were significantly associated with episiotomy, instrumental delivery and increased hiatal measurements. Palpation was unreliable early postpartum as only seven avulsions were diagnosed.

Hematomas at the site of LAM attachment to the pubic bone always result in avulsion diagnosed 3 months postpartum. However, one third of avulsions are not preceded by a hematoma at the site of LAM attachment to the pubic bone.