Post-Aspiration Balloon Reinjection During Urethral Catheter Removal in Adult Men and Women: A Systematic Review and...

Background: Guidance on catheter removal addresses passive balloon deflation and cuffing, but the comparative effect of small-volume reinjection after complete aspiration remains uncertain. This review evaluated reinjection versus conventional complete aspiration in adult men and women. Methods: The review was registered in PROSPERO (CRD420261451421) after the initial search and preliminary analyses had begun. Eight English- and Chinese-language databases were formally searched from inception to 9 July 2026. Randomized and quasi-randomized controlled trials of routine transurethral catheter removal were eligible. The primary outcome was pain experienced during withdrawal of the deflated balloon through the urethra, measured during removal or at the earliest immediate post-removal assessment. Pain was pooled as Hedges' g; a harmonized 0-10 mean difference was examined for interpretability. Secondary outcomes were pooled as risk ratios. Risk of bias was assessed with Risk of Bias 2 and certainty with GRADE. Results: Forty-six Chinese trials (6395 participants; both sexes represented) were included: 35 were reported as randomized and 11 used predictable quasi-random allocation. Sex-stratified outcome data were not available. Reinjection was associated with less pain (26 trials; SMD -1.14, 95% CI -1.35 to -0.92; I² = 89.8%; 95% prediction interval -2.25 to -0.03); the harmonized 0-10 mean difference was -1.73 points (95% CI -2.11 to -1.35). Associations also favored reinjection for urinary retention (RR 0.22; low certainty), successful spontaneous voiding (RR 1.29; very low certainty), any hematuria (RR 0.21; very low certainty), macroscopic hematuria (RR 0.28; low certainty), microscopic hematuria (RR 0.34; very low certainty), and catheter reinsertion (RR 0.44; low certainty). Infection-related adverse events were not reported in extractable comparative form. Conclusions: Reinjection was associated with lower pain and fewer removal-related events compared with active complete aspiration, but certainty is low or very low, heterogeneity is substantial, all evidence is from one country, and sex-specific effects and the influence of prostatic hyperplasia or catheter diameter could not be assessed. The findings do not establish superiority over passive balloon deflation or support routine international implementation.