Factors predicting a failed primary repair of obstetric anal sphincter injury

The success of the primary repair of obstetric anal sphincter injury (OASI) is paramount in maintaining adequate fecal continence after childbirth. The factors determining the success or failure of primary repair are unclear. The aim of this study is to investigate modifiable factors determining the success or failure of the primary sphincter repair after OASI.

Sixty women with OASI were investigated by endoanal ultrasound or magnetic resonance imaging, and with the Wexner incontinence questionnaire. Based on the findings, the women were divided in two groups; successful primary repair group (n = 41) and failed primary repair group (n = 19).

The primary repair failed in 31.7% of the tears. These included more tears repaired by less experienced personnel (p < 0.001) and more repairs performed during on-call hours (p = 0.039) than in the successful primary repair group. Significantly more pain medication was used in the failed group (p = 0.003), and the use of antibiotics and laxatives after the repair was more common in the successful group (p < 0.001). Sphincter injuries were repaired using the overlapping suture technique in 95.1% of the repairs in the successful group compared with 47.4% in the failed group (p = 0.03). The mean (SD) Wexner score was significantly higher in the failed group [5.92 (4.1) vs. 1.88 (4.2), p < 0.001], in agreement with the findings on endoanal ultrasound.

Postpartum perineal tears should be evaluated by personnel familiar with the diagnosis and repair of OASI. Delaying the primary repair until next morning is recommended if experienced personnel are unavailable during on-call hours.