Antibiotics After Operative Delivery Prevent Infection Irrespective of Perineal Trauma

Timely antibiotic prophylaxis with amoxicillin and clavulanic acid after operative vaginal birth decreases the risk for infection irrespective of perineal trauma.

Results of a study published in the American Journal of Obstetrics and Gynecology found that all women should receive timely prophylactic antibiotics to prevent infection following operative vaginal birth, including those with perineal trauma.

In this post hoc analysis, researchers evaluated primary outcome data sourced from a randomized control trial (RCT) comprising women (N=3225) who gave birth assisted by forceps or vacuum between 2016 and 2018. Patients included in the RCT were randomly assigned in a 1:1 fashion to receive either a single intravenous dose of amoxicillin and clavulanic acid or placebo no more than 6 hours after operative vaginal birth. The primary outcome for this post-hoc analysis was to determine whether prophylactic antibiotics decrease the risk for confirmed or suspected infection at 6 weeks irrespective of perineal trauma.

Among 2925 patients included in a multivariable risk factor analysis, 425 did and 2473 did not develop confirmed or suspected infection following operative vaginal delivery. Of these 2 patient groups, the mean age was 30.5 and 30.4 years, the median gestational age was 40.1 and 40.3 weeks, the median BMI was 25.1 and 24.5 kg/m2, 16.6% and 83.4% were primiparous, 17.7% and 82.3% had a forceps-assisted birth, 16.4% and 83.6%% had episiotomy, and 15.5% and 84.5% received amoxicillin and clavulanic acid, respectively.

In patients who had no perineal trauma, the overall infection rate was 11.1% among those who received amoxicillin and clavulanic acid and 19.1% among those who received placebo.

Further analysis was performed among patients who did experience perineal trauma. Compared with receipt of placebo, receipt of prophylactic antibiotics was associated with decreased risk for infection among patients who experienced tear only (risk ratio [RR], 0.20; 95% CI, 0.04-0.87), episiotomy only (RR, 0.66; 95% CI, 0.53-0.81), and those who experienced both episiotomy and tear (RR, 0.50; 95% CI, 0.37-0.69).

Analysis of this large prospective cohort of women undergoing OVB suggests that prophylactic amoxicillin and clavulanic acid is protective against confirmed or suspected infection following perineal trauma whether or not an episiotomy is used.

Overall, receipt of prophylactic antibiotics after operative vaginal delivery was found to be protective against infection compared with placebo (RR, 0.60; 95% CI, 0.51-0.72).

Factors significantly associated with infection risk included episiotomy (RR, 2.94; 95% CI, 1.62-5.31) and forceps-assisted delivery (RR, 1.37; 95% CI, 1.12-1.69). After adjustments for BMI, mode of birth, episiotomy, and parity, the researchers found the risk for infection increased by 3% for every 15-minute interval between delivery and receipt of amoxicillin and clavulanic acid.

Limitations include potential residual confounding, and the study may have been underpowered due to its post hoc design.

According to the researchers, “Analysis of this large prospective cohort of women undergoing OVB [operative vaginal birth] suggests that prophylactic amoxicillin and clavulanic acid is protective against confirmed or suspected infection following perineal trauma whether or not an episiotomy is used.

References:

Humphreys ABC, Linsell L, Knight M. Factors associated with infection following operative vaginal birth – a secondary analysis of the ANODE randomized controlled trial. Am J Obstet Gynecol. 2022;S0002-9378(22)00679-2. doi:10.1016/j.ajog.2022.08.037