A Cochrane review included 26 studies with a total of 2 933 subjects. There was no significant difference in need for recatheterisation (11 RCTs, n=1 389). Following urological surgery and procedures, patients whose indwelling urethral catheters were removed at midnight passed significantly larger volumes at their first void (Difference [fixed] 96 ml; 95% CI 62 to 130). Similar findings were reported for patients following TURP (Difference [fixed] 27; 95% CI 23 to 31). Removal at midnight was also associated with longer time to first void, and shorter lengths of hospitalisation (relative risk of not going home on day of removal = 0.71, 95% CI 0.64 to 0.79). Participants having early rather than delayed catheter removal were consistent with a higher risk of voiding problems and a lower risk of infection, with shorter hospitalisation (13 trials, n=1422). The data were too few (3 trials, n=234) to assess differential effects of catheter clamping compared with free drainage prior to withdrawal.
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison) and by inconsistency (heterogeneity in interventions and outcomes).