The estimated prevalence of levator ani muscle (LAM) injury after vaginal delivery ranges from 13% to 36%. Levator ani muscle injury is associated with pelvic organ prolapse, but its association with stress incontinence is unclear. Differences have been demonstrated between white and Chinese women in structural and pelvic organ mobility. There are limited data on the effect of LAM injury on health-related quality of life.
This prospective observational study evaluated the effect of LAM injury on pelvic floor disorders and health-related quality of life in Chinese primiparous women during the first year after delivery. At 8 weeks and 12 months after delivery, women with and without LAM injury were assessed for symptoms of pelvic floor disorders and quality of life using the standardized questionnaire (Pelvic Organ Prolapse Quantification [POP-Q]); translabial ultrasound was used to detect LAM injury. A total of 442 women were recruited in a tertiary obstetric unit during the first trimester from August 2009 to September 2010. Data were analyzed using descriptive analysis, independent-sample t test, nonparametric testing, χ2 test, and 2-sided Fisher exact test.
Of the 442 women enrolled, 328 (74.2%) completed the study. At 8 weeks after delivery, LAM injury was detected in 48 women (19.0% [95% confidence interval, 14.2%–23.8%]) with vaginal delivery; 12 months after delivery, the injury persisted in 38 women (79.2%).
Eight weeks after delivery, LAM injury was associated with prolapse symptoms, descent at POP-Q Aa and Ba points, and higher Pelvic Organ Prolapse Distress Inventory and Urinary Distress Inventory Obstructive subscale scores.
By 12 months, LAM injury was not associated with prolapse symptoms or with either Pelvic Floor Distress Inventory (PFDI) or Pelvic Floor Impact Questionnaire (PFIQ) scores. At both time points, no association was found between stress urinary incontinence, urge urinary incontinence, mixed urinary incontinence, and fecal incontinence with LAM injury.
In this prospective cohort, LAM injury persisted 12 months after vaginal delivery in 79% of women who had LAM injury at 8 weeks. Eight weeks after delivery, LAM injury was associated with prolapse symptoms, lower POP-Q Aa and Ba points, and higher Pelvic Organ Prolapse Distress Inventory general and Urinary Distress Inventory Obstructive subscale scores. However, there was no association between LAM injury and stress urinary incontinence, urge urinary incontinence, mixed urinary incontinence, and fecal incontinence at 8 weeks or 12 months after delivery, or prolapse symptoms, PFDI, or PFIQ scores at 12 months after delivery.