The quality ov evidence is downgraded by study limitations (unclear allocation concealment or blinding in half of the studies).
A Cochrane review included 11 studies with a total of 3403 subjects. The risk of bias was generally low, with the quality of most of the studies being high. Vaginal preparation (povidone-iodine, chlorhexidine, benzalkonium chloride) immediately before cesarean delivery significantly reduced the incidence of post-cesarean endometritis from 8.7% in control groups to 3.8% in vaginal cleansing groups (average risk ratio (RR) 0.36, 95% CI 0.20 to 0.63; 10 trials, n=3283). The risk reduction appeared stronger for women who were already in labor at the time of the cesarean delivery and for women with ruptured membranes.