[Levator ani trauma after childbirth, from stretch injury to avulsion: review of the literature].

OBJECTIVE: Pelvic floor injuries as avulsion (disruption of the muscle) or overdistension were identified in 15 to 35% of deliveries. Our objective is to clarify the consequences of these muscles trauma on pelvic floor symptoms, pelvic organ prolapse and the management of postnatal assessment of pelvic floor function.
METHOD: The literature search was conducted over a period from 2000 to January 2013 using the PubMed database and the following keywords: levator ani, ultrasound, magnetic resonance imaging, pelvic floor, obstetric trauma, pelvic organ prolapse, incontinence, delivery, avulsion. Seventy-four articles were identified, 43 were selected. The level of evidence was determined using the Oxford table.
RESULTS: The instrumental extraction was found as the main risk factor with a prevalence of avulsions from 35% (NP3) to 72% (NP3) and an odd-ratio of 3.4 (NP3). Whatever the mode of assessment, the strength of the pelvic floor was reduced in 100% of cases of avulsion. Avulsions were diagnosed clinically and could be confirmed by ultrasound or MRI (correlation palpation imaging/k=0.497 (NP2) to 86% (NP3). An association was found with the risk of genital prolapse (odd-ratio from 2 [NP4] to 7 for prolapse grade 1 [NP4]) and fecal incontinence (16% [NP3] to 72% [NP4] with an odd-ratio of 14 [NP4]).
CONCLUSION: This review has shown that obstetric muscle avulsions had an impact on pelvic organ prolapse and anal continence. The mode of the pelvic floor muscle postnatal assessment remains to be defined.