Multichannel urodynamic study (UDS) is essential for diagnosing lower urinary tract dysfunction, especially in patients with neurological disease or refractory symptoms. However, its invasive nature poses a risk for post-procedural urinary tract infections (UTIs). The Best Practice Policy Statement (BPPS) discourages routine antibiotic prophylaxis in low-risk "index" patients, though evidence supports potential benefit in high-risk individuals. The clinical value of prophylactic antibiotics in non-index, high-risk populations remains unclear. This study aims to evaluate whether prophylactic antibiotics reduce post-UDS UTIs, especially in patients with known high-risk features.

This retrospective cohort study included patients who underwent multichannel UDS at our institution between January and September 2024. Baseline characteristics, history of neurogenic lower urinary tract dysfunction, catheter use, immunosuppression status, prior recurrent UTI, and urodynamic parameters were collected. All UDS procedures followed International Continence Society (ICS) standards. Antibiotic prophylaxis was clinician-dependent but typically withheld in index patients. Post-UDS symptomatic UTI was defined as a new-onset, symptomatic, culture-proven UTI within 30 days. Febrile UTI was defined by concurrent fever >38°C. Statistical analyses included chi-square tests and logistic regression to identify risk factors. Subgroup analyses evaluated prophylaxis effects in high-risk subpopulations.

Among the 254 patients analyzed (166 males, 88 females; mean age 64.1 ± 16.5 years), 113 (44.4%) received prophylactic antibiotics. Overall, 32 patients (12.6%) developed symptomatic UTIs following urodynamic study (UDS), including 12 (4.7%) febrile UTIs. Prophylactic antibiotic use was not significantly associated with a reduced incidence of symptomatic (p = 0.166) or febrile UTIs (p = 0.771). Multivariate analysis identified elevated post-void residual (PVR >100 mL) (OR = 5.73, p < 0.001) and catheter use (OR = 4.96, p < 0.001) as independent risk factors for post-UDS symptomatic UTIs. Subgroup analyses showed no protective antibiotic effect in patients with elevated PVR (p=0.660) or catheter use (p=0.253).

Elevated PVR and catheter use are significant risk factors for post-UDS infections. Prophylactic antibiotics did not demonstrate protective efficacy, even among high-risk patients.