Risk and Outcome of Obstetrical Anal Sphincter Injury

In Brief Objective: To describe risk factors for sustaining anal sphincter injury during vaginal delivery and to describe the frequency of short-term complications. Methods: A case-control review of 83 patients sustaining third or fourth degree obstetrical lacerations and a group of 166 controls. Univariate and multivariate logistic regression analyses were performed. The frequency of wound complications and perineal/anal symptoms was calculated. Results: The presence of chorioamnionitis, use of forceps, midline episiotomy, first delivery, larger birth weight, and longer second stage of labor (P < 0.02) had increased odds ratios for association with anal sphincter lacerations using univariate analysis. Only use of forceps and midline episiotomy (P < 0.02) demonstrated significantly increased odds ratios using a logistic multivariate model. Following repair of anal sphincter lacerations, the rate of wound breakdown was 2% and the rate of wound infection was 5%, which were unrelated to the degree of laceration. Of 62 patients with follow-up documentation, 21% complained of some degree of anal incontinence, pain with defecation, dyspareunia, or anal urgency. Conclusions: Risk factors for anal sphincter injury include use of forceps and midline episiotomy. Wound breakdown and infection frequencies were not different between third and fourth degree lacerations. Risk factors for recognized obstetrical anal sphincter injury include use of forceps and midline episiotomy. In the short term, one-fifth of patients complained of some degree of adverse symptoms related to third or fourth degree laceration.