How many urinalysis and urine cultures are necessary?

Background: Urinalysis and urine culture are two of the most commonly ordered tests. A positive urine test in asymptomatic patients often leads to overtreatment. Antimicrobials for asymptomatic bacteriuria is one of the most common unnecessary treatments. We aimed to explore the current ordering patterns of urinalysis and cultures.

Methods: This is a substudy of the multicentre RICAT-trial, a successful quality improvement project to reduce inappropriate use of intravenous and urinary catheters in seven hospitals in the Netherlands. Adult patients with a (central or peripheral) venous or urinary catheter admitted to internal medicine and non-surgical subspecialty wards were eligible for inclusion. Data were collected every other week during baseline (seven months) and intervention periods (seven months). The primary outcome was the proportion of urine cultures performed following a negative urinalysis, i.e. dipstick and/or microscopic analysis, within 24 h.

Results: Between September 2016 and April 2018, we included 3748 patients, of which 3111 (83%) were admitted from the emergency department. Urinalysis and/or urine cultures were obtained in 2610 (70%) of 3748 patients. 626 (23.7%) of 2636 urine cultures and 1351 (55.8%) of 2419 microscopic analysis were unnecessary performed after a negative urinalysis. Cancelling urine testing orders after a negative dipstick would have saved almost € 19.500 during the study period in these seven hospitals.

Conclusion: Unnecessary urine testing is frequent in non-surgical patients in the Netherlands. We need to take action to reduce unnecessary urinalysis and cultures, and thereby probably reduce overtreatment of asymptomatic bacteriuria.