Background: One to eight per cent of women suffer third-degree perineal tear (anal sphincter injury) and fourth-degree perineal tear (rectal mucosa injury) during vaginal birth, and these tears are more common after forceps delivery (28%) and midline episiotomies. Third- and fourth-degree tears can become contaminated with bacteria from the rectum and this significantly increases in the chance of perineal wound infection. Prophylactic antibiotics might have a role in preventing this infection.
Objectives: To assess the effectiveness of antibiotic prophylaxis for reducing maternal morbidity and side effects in third- and fourth-degree perineal tear during vaginal birth.
Search strategy: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 August 2010) and the reference lists of retrieved articles.
Selection criteria: Randomised controlled trials comparing outcomes of prophylactic antibiotics versus placebo or no antibiotics in third- and fourth-degree perineal tear during vaginal birth.
Data collection and analysis: Two review authors independently assessed the reports and extracted data.
Main results: We identified and included one trial (147 participants) that compared the effect of prophylactic antibiotic (single-dose, second generation cephalosporin, intravenously) on postpartum perineal wound complications in third- or fourth-degree perineal tears. Perineal wound complications (wound disruption and purulent discharge) at the two-week postpartum check up were 8.20% and 24.10% in the treatment and the control groups respectively (risk ratio 0.34, 95% confidence interval 0.12 to 0.96).
Authors' conclusions: Although the data suggest that prophylactic antibiotics help to prevent perineal wound complications following third- or fourth-degree perineal tear, loss to follow-up was very high. The results should be interpreted with caution as they are based on one small trial.