Abstract: The search retrieved 16 studies (from 17 reports). Ten studies were excluded and one study is awaiting assessment. We included five studies involving 1065 women (1090 recruited). The five included studies were at moderate risk of bias. Data relating to one of our primary outcomes (UTI) was reported in four studies but did not meet our definition of UTI (as prespecified in our protocol). The included studies did not report on our other primary outcome – intraoperative bladder injury (this outcome was not prespecified in our protocol). Two secondary outcomes were not reported in the included studies: need for postoperative analgesia and women’s satisfaction. The included studies did provide limited data relating to this review’s secondary outcomes. Indwelling bladder catheter versus no catheter - three studies (840 women) Indwelling bladder catheterisation was associated with a reduced incidence of bladder distension (non-prespecified outcome) at the end of the operation (risk ratio (RR) 0.02, 95% confidence interval (CI) 0.00 to 0.35; one study, 420 women) and fewer cases of retention of urine (RR 0.06, 95% CI 0.01 to 0.47; two studies, 420 women) or need for catheterisation (RR 0.03, 95% CI 0.01 to 0.16; three studies 840 participants). In contrast, indwelling bladder catheterisation was associated with a longer time to first voiding (mean difference (MD) 16.81 hours, 95% CI 16.32 to 17.30; one study, 420 women) and more pain or discomfort due to catheterisation (and/or at first voiding) (average RR 10.47, 95% CI 4.71 to 23.25, two studies, 420 women) although high levels of heterogeneity were observed. Similarly, compared to women in the ‘no catheter’ group, indwelling bladder catheterisation was associated with a longer time to ambulation (MD 4.34 hours, 95% CI 1.37 to 7.31, three studies, 840 women) and a longer stay in hospital (MD 0.62 days, 95% CI 0.15 to 1.10, three studies, 840 women). However, high levels of heterogeneity were observed for these two outcomes and the results should be interpreted with caution. There was no difference in postpartum haemorrhage (PPH) due to uterine atony. There was also no difference in the incidence of UTI (as defined by trialists) between the indwelling bladder catheterisation and no catheterisation groups (two studies, 570 women). However, high levels of heterogeneity were observed for this non-prespecified outcome and results should be considered in this context. Indwelling bladder catheter versus bladder drainage – two studies (225 women) Two studies (225 women) compared the use of an indwelling bladder catheter versus bladder drainage. There was no difference between groups in terms of retention of urine following CS, length of hospital stay or the non-prespecified outcome of UTI (as defined by the trialist). There is some evidence (from one small study involving 50 women), that the need for catheterisation was reduced in the group of women with an indwelling bladder catheter (RR 0.04, 95% CI 0.00 to 0.70) compared to women in the bladder drainage group. Evidence from another small study (involving 175 women) suggests that women who had an indwelling bladder catheter had a longer time to ambulation (MD 0.90, 95% CI 0.25 to 1.55) compared to women who received bladder drainage. This review includes limited evidence from five RCTs of moderate quality. The review's primary outcomes (bladder injury during operation and UTI), were either not reported or reported in a way not suitable for our analysis. The evidence in this review is based on some secondary outcomes, with heterogeneity present in some of the analyses. There is insufficient evidence to assess the routine use of indwelling bladder catheters in women undergoing CS. There is a need for more rigorous RCTs, with adequate sample sizes, standardised criteria for the diagnosis of UTI and other common outcomes.

Plain-language summary: This review is based on five studies involving 1065 women undergoing CS. The studies were of moderate quality. The included studies did not use this review's criteria for diagnosis for UTI, so there are no data for this primary outcome. When considering UTI, as defined by the trial authors, there were no clear differences between groups. There were no data relating to bladder injury during the CS (the review's other primary outcome). Our analysis showed that the use of urinary catheter was associated with less retention of urine after CS. On the other hand, pain/discomfort due to catheterisation or at first voiding after CS, time to ambulate and hospital stay favoured non-use of urinary catheter. There was no difference in the incidence of uterine bleeding due to uterine atony (relaxation of the uterus) after the delivery. The limited evidence in this review is based five trials of moderate quality and results should be considered in this context. There is not enough evidence to assess the routine use of indwelling bladder catheters in women undergoing CS. There is a need for more rigorous research on this topic and future trials should use a standardised criteria for the diagnosis of UTI and other common outcomes.