Risk Factors for Wound Complications After Obstetric Anal Sphincter Injury

Objectives: To evaluate for characteristics associated with wound complications after obstetric anal sphincter injury (OASI). We hypothesized that operative delivery would be associated with wound complications and that peripartum antibiotics would be protective.

Methods: We performed a retrospective cohort study of all patients who sustained obstetric anal sphincter injuries (OASIs) and were evaluated in a specialized postpartum pelvic floor healing clinic at a large, academic center between November 1, 2020 and May 16, 2023. OASI was defined as a 3rd or 4th degree obstetric laceration. Patients who delivered via cesarean delivery or did not sustain an OASI at the time of delivery were excluded. Our primary outcome was wound complications defined as wound infection, wound breakdown or dehiscence, need for additional antibiotics, or need for additional surgical intervention. The electronic medical records were reviewed for demographics, intrapartum, and postpartum factors. This was a convenience sample and thus no a priori sample size calculation was performed. Independent t-tests, chi-square, and Fisher's exact tests were utilized for statistical comparison. Multivariable logistic regression with backward stepwise selection was used to identify and remove redundant independent variables.

Results: The cohort consisted of 332 patients who had sustained OASIs: 294 (88.6%) 3rd degree and 38 (11.4%) 4th degree lacerations. A total of 74 (22.3%) patients experienced a wound complication. There were 31 (9.3%) wound infections and 62 (18.7%) wound breakdowns. Fifty (15.1%) patients received additional antibiotics and 20 (6.0%) patients required additional surgical intervention in the operating room. On univariate analysis, those who experienced wound complications were older (31.9 years vs 30.6 years, p=0.01) and more likely to have had an episiotomy (23.0% vs 12.5%, p=0.03) (Tables 1 and 2). Episiotomy type (midline vs mediolateral) was not significantly associated with OASI wound complications (p=0.15). Those who experienced OASI wound complications were more likely to undergo an in-office procedure (p < 0.001), particularly treatment with silver nitrate (p < 0.001) (Table 2). Patients with wound complications were more likely to report postpartum pain or dyspareunia (p < 0.001), urinary incontinence (p=0.02), fecal urgency (p=0.02), and "other" symptoms such as urinary retention (p=0.04) (Table 2). On multivariable logistic regression analysis, older age was associated with an increased odds of wound complication (OR 1.1, 95% CI 1.01-1.13, p=0.03) and peripartum antibiotics were associated with a decreased odds of wound complication (OR 0.57, 95% CI 0.33-0.97, p=0.04).

Conclusions: In a cohort of patients with OASIs who sought care at a postpartum pelvic floor healing clinic, older maternal age was associated with wound complications while peripartum antibiotics were protective. Patients with OASI wound complications were more likely to report postpartum pelvic floor symptoms and undergo in-office procedures, emphasizing the need for attentive and focused postpartum care for patients who experience OASI.