Clinical implications of uterine cultures obtained during urgent caesarean section

Postpartum endometritis (PPE) is 12-25 times more common following caesarean sections (CS) performed after labour onset than after vaginal delivery. Risk factors for PPE include prolonged rupture of membranes (ROM), chorioamnionitis, prolonged labour, multiple cervical examinations and Group B Streptococcus colonisation of the lower genital tract.

We compared uterine culture results and microbial antibiotic susceptibility according to ROM duration in emergent intrapartum CS. Secondary outcomes included PPE incidence, and identification of clinical and microbiological predictors of infectious postpartum morbidity.

In a retrospective case series of intrapartum CS in which uterine culture was performed, associations with postpartum outcomes including postpartum microbiology are reported. The results were stratified by the duration of ROM (treated as a categorical variable). Univariate analysis was performed.

Positive uterine cultures were identified in 15% of emergent CS and correlated with prolonged ROM. Escherichia coli was the sole pathogen isolated in preterm CS; the ampicillin resistance rate was 75%. Among women with positive uterine cultures, rates were increased for postpartum fever, re-admission, PPE and surgical site infection. Cultures obtained from postpartum infections correlated with pathogens isolated from uterine cultures during CS in 46.1% of women. Positive uterine culture was related to umbilical cord pH < 7.1 (P = 0.017).

Obtaining routine intrauterine culture during intrapartum CS is of low risk and low cost, and relatively easy to perform. Further research should investigate clinical and health economic impacts of obtaining intrauterine culture during CS, influences on postpartum antibiotic treatment, and maternal and neonatal morbidity.