Risk factors associated with deep perineal wound dehiscence after second‐degree perineal tears or episiotomy

Abstract Introduction Second‐degree perineal tears and episiotomies, involving the bulbocavernosus and/or superficial transverse perineal muscles, are common after vaginal birth and may lead to wound dehiscence, infection, and long‐term pelvic floor dysfunction. Despite this, risk factors for deep wound dehiscence involving perineal musculature remain insufficiently studied. This study aimed to identify risk factors for wound dehiscence in second‐degree tears and episiotomies to inform potential use of antibiotic prophylaxis. Material and Methods A single‐center case–control study (1:2 ratio) was conducted including 105 cases with 2nd degree perineal tears or episiotomies complicated by deep wound dehiscence, diagnosed within two weeks postpartum and 210 controls with second‐degree tears or episiotomies without dehiscence. Exposure data were retrieved from medical records. Univariate analyses were performed on a priori selected exposure variables, using Mann–Whitney U and Fisher's exact tests. Variable selection used Lasso regression with leave‐one‐out cross‐validation. Multivariate logistic regression generated adjusted odds ratios (aOR). Statistical significance was set at p < 0.05. Results Women with wound dehiscence were more often vaginal primiparas (87% vs 69%, p < 0.001) and had higher rates of episiotomy (33% vs 7%, p < 0.001). Intrapartum antibiotics were administered less frequently among cases (7% vs 20%, p = 0.002). Cases had longer second stage of labor, more active pushing, and greater postpartum bleeding. After multivariate adjustment, only episiotomy (aOR 4.40, 95% CI 2.10–9.64) and intrapartum antibiotic administration (aOR 0.21, 95% CI 0.07–0.50) remained significantly associated with wound dehiscence. Conclusions Episiotomy substantially increased the risk of deep perineal wound dehiscence compared with spontaneous second‐degree perineal tears, while intrapartum antibiotics were protective. These findings support selective episiotomy use and suggest that antibiotic prophylaxis may reduce this risk in women with second‐degree perineal tears or episiotomies.