Clinical Decisionmaking

Urethral catheterization to diagnose urinary tract infections in feverish infants is questioned

Urinary tract infections (UTIs) are the most common cause of serious bacterial infections in feverish infants younger than 3 months, but there is a debate over the optimal method of urine collection to diagnose UTIs in these infants. According to a study supported in part by the Agency for Healthcare Research and Quality (HS06485), most doctors use urethral catheterization; however, its accuracy is only marginally better than bag collection. Urethral catheterization is considered more accurate than bag collection, but is technically difficult, invasive, and painful.

Researchers examined urine collection methods to diagnose UTI among 3,066 infants 3 months or younger (fever of 38 degrees C or higher) cared for in 219 practices from within the Pediatric Research in Office Settings' multistate network. Overall, 70 percent of urine samples were obtained by catheterization. Predictors of catheterization included infant female sex, practitioner older than 40 years, Medicaid insurance, Hispanic ethnicity, nighttime evaluation, and infants' severe dehydration.

Urinary specimens from bag and catheterization methods had similar sensitivity for detecting the number of white blood cells in the urine (leukocyte esterase levels), which indicates infection. However, bag specimens had somewhat lower specificity (84 vs. 94 percent), that is, they had many more false positives. The poorer specificity of bag specimens is of greater concern for doctors who manage UTIs aggressively with routine hospitalization and imaging. Ultimately, the choice of urine collection method should incorporate a number of factors, including patient age, parental preference, need for immediate diagnosis and/or antibiotic treatment, and plans for future imaging, suggest the researchers.

See "Choice of urine collection methods for the diagnosis of urinary tract infection in young, febrile infants," by Alan R. Schroeder, M.D., Thomas N. Newman, M.D., M.P.H., Richard C. Wasserman, M.D., M.P.H., and others, in the October 2005 Archives of Pediatric and Adolescent Medicine 159, pp. 915-922.

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