Reassessing the utility of routine urine culture with urodynamics: UTI incidence and risk factors.

INTRODUCTION: There is no consensus regarding use of periprocedural antibiotics or routine urine cultures during urodynamics study (UDS) in children. At our hospital, we historically have obtained urine cultures during UDS. However, even with positive cultures, few patients require treatment. Most are successfully managed with increased hydration and frequent bladder emptying.

PURPOSE: To evaluate clinical characteristics, antibiotic treatment, and outcomes in patients undergoing UDS to identify (1) risk factors for urinary tract infection (UTI) after UDS, and (2) patients who may benefit from routine urine culture.

STUDY DESIGN: Retrospective review of 769 patients who underwent 1057 UDS between January 2013 and January 2015. Positive urine culture was defined as ≥104 colony forming units/ml. Afebrile UTI was defined as new symptoms within 7 days. Febrile UTI was new symptoms with fever (≥38.5 °C). Fisher's exact test was used for comparative analyses.

RESULTS: Nearly all patients had a urine culture taken immediately prior to UDS (94%, 993/1057). Patients on clean intermittent catheterization (CIC) were more likely to be on pre-UDS antibiotics, 22.8% (106/464) vs. 17.9% of those not on CIC (106/593) (p = 0.04). Of patients who had a urine culture, it was positive in 40% (402/993) with more positive cultures in patients on CIC vs. not (72.0%, 316/439 vs. 15.5%, 86/554, p < 0.0001). Factors significantly associated with clinical/possible post-UDS UTI included clinical UTI within 30 days before UDS, immunosuppression, overnight Foley catheter use, febrile UTI as indication, and symptoms on day of procedure (Table). Fifteen patients (1.4%, 95% confidence interval 0.7-2.1%) developed a clinical/possible post-UDS UTI, of which 40% (6/15) were febrile, with one requiring hospitalization. Of patients with post-UDS UTIs, 33% (5/15) had negative cultures at the time of UDS.

DISCUSSION: If urine cultures were obtained selectively based on our study findings, 78% of pre-UDS urine cultures could be eliminated, while "missing" clinically relevant cultures in only 0.4% (4/1057). Study limitations include the retrospective design. However, prospective data collection will now be possible by using standardized, templated UDS and post-UDS follow-up notes with extractable data elements that automatically populate a database.

CONCLUSION: Post-UDS UTI is uncommon (1.4%), even in the setting of bacteriuria. This finding calls into question the utility of routine pre-UDS urine culture. Data from this study and a future prospective study will be used to refine a new working protocol, with the goal of targeting future urine cultures to a high-risk subset of patients.