Urinalysis is a readily available test often used for screening. Pyuria is a common finding in asymptomatic patients; however, it is unknown how often identification of pyuria in the absence of confirmatory cultures leads to antimicrobial prescribing. The objective of this study was to measure the association between pyuria and antimicrobial initiation during the perioperative period and assess harms versus benefits of treatment.

A retrospective cohort of preoperative patients within the national healthcare system during the period 1 October 2008–30 September 2013 who had a urinalysis performed during the 30-day preoperative period was created; patients with positive urine cultures were excluded. The primary exposure was pyuria on preoperative urinalysis. The primary outcome was antimicrobial initiation. Secondary outcomes included postoperative surgical site (SSI), urinary tract (UTI), and Clostridioides difficile infections. Trend and logistic regression analyses were performed.

Among 41 373 patients, 3617 had pyuria. 887 (24.5%) patients with pyuria received antimicrobials versus 1918 (5.1%) patients without pyuria. As the degree of pyuria increased, the odds of receiving antimicrobials also increased linearly (low, 14.7%; moderate, 24.0%; high pyuria, 37.4%). Preoperative pyuria was associated with postoperative C. difficile infections (aOR, 1.7; 95% CI, 1.2–2.4); risk was higher in patients who received antimicrobials (aOR, 2.4; 1.7–3.4). Pyuria was not associated with SSI but was associated with increases in UTI after orthopedic and vascular procedures; this risk was not mitigated by antimicrobial therapy.

Urine screening during the preoperative period is a low-value intervention that increases antimicrobial exposure but does not improve postoperative outcomes.