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Letter to the Editor

Best Evidence on Clean-Catch Urine Samples

doi: 10.1097/01.EEM.0000552808.35348.c7
Letter to the Editor


We read the article, “The Myth of Midstream Clean-Catch Urine Samples” (EMN 2018;40[10]:43; with great interest because asymptomatic bacteriuria and urine specimen collection are significant areas of interest for our emergency department antibiotic stewardship program. (J Emerg Med 2016;51[1]:25.) We agree with the authors' overall message, but the article misses the mark on three important points.

First, clean-catch urine collection may not reduce culture contamination rates, but the diagnostic performance of urinalysis degrades rapidly in the presence of squamous epithelial cells, which are associated with an increased rate of pyuria (WBCs in the UA). (Acad Emerg Med 2016;23[3]:323.) UTIs in the ED are primarily diagnosed using UA results, so pyuria may bias clinicians toward the presence of infection and result in unnecessary antibiotics. Rather than abandon the midstream clean-catch, we advocate implementation research aimed at mitigating factors that result in poor patient compliance with the technique. (J Emerg Med 2017;52[5]:639; J Clin Pathol 2016;69[10]:921; Am J Emerg Med 2018;36[1]:61.)

Second, visual inspection of urine clarity is misleading in diagnosing UTI because it is more likely related to hydration status or the quantity of urea in the sample. The positive predictive value of cloudy urine for UTI has been reported at only 40%. (J Am Board Fam Med 2011;24[4]:474.)

Finally, the literature does not support diagnosing UTI based on “typical” symptoms without a UA. The probability of UTI in women presenting with urinary complaints is only 50 percent. (JAMA 2002;287[20]:2701; Ann Emerg Med 2007;49[1]:106.) To reduce overuse of antibiotics and the associated patient safety and public health implications, UTI should be diagnosed only after consideration of symptoms, physical examination findings, and the UA.

Robert S. Redwood, MD, MPH

Portage, WI

Barry Fox, MD, &

Michael S. Pulia, MD

Madison, WI

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