Objective
To describe occurrence, recovery, and consequences of musculoskeletal injuries in women at-risk for childbirth-related pelvic floor injury at first vaginal birth.
Study Design
Evaluating Maternal Recovery from Labor and Delivery (EMRLD) is a longitudinal cohort design study of women recruited early post-birth and followed over time. We report here on 68 women who had birth-related risk factors for levator ani muscle injury, including long second stage, anal tears, and/or older maternal age, and who were evaluated by musculoskeletal magnetic resonance imaging at both 7-weeks and 8-months postpartum. We categorized magnitude of injury by extent of bone marrow edema, pubic bone fracture, levator ani muscle edema, and levator ani muscle tear. We also measured the force of levator ani muscle contraction, urethral pressure, pelvic organ prolapse, and incontinence.
Results
In this higher-risk sample, 66% (39/59) had pubic bone marrow edema, 29% (17/59) had subcortical fracture, 90% (53/59) levator ani muscle edema, and 41% (28/68) low-grade or greater levator ani tear 7-weeks postpartum. The magnitude of levator ani muscle tear did not substantially change by 8-months postpartum (p=0.86), but levator ani muscle edema and bone injuries showed total or near total resolution (p<.05). The magnitude of unresolved musculoskeletal injuries correlated with magnitude of reduced levator ani muscle strength and posterior vaginal wall descent (p<.05) but not with urethral pressure, volume of demonstrable stress incontinence, nor self-report of incontinence severity (p>.05).
Conclusion
Pubic bone edema and subcortical fracture and levator ani muscle injury are common when studied in women with certain risk factors. The bony abnormalities resolve, but levator tear does not, and is associated with levator weakness and posterior-vaginal wall descent.