title: Abnormal urinalysis results are common, regardless of specimen collection technique, in women without urinary tract infections.
abstract: BACKGROUND
  Voided urinalysis to test for urinary tract infection (UTI) is prone to false-positive results for a number of reasons. Specimens are often collected at triage from women with any abdominal complaint, creating a low UTI prevalence population. Improper collection technique by the patient may affect the result. At least four indices, if positive, can indicate UTI.
  
  
  OBJECTIVE
  We examine the impact of voided specimen collection technique on urinalysis indicators of UTI and on urine culture contamination in disease-free women.
  
  
  METHODS
  In this crossover design, 40 menstrual-age female emergency department staff without UTI symptoms collected urine two ways: directly in a cup ("non-clean") and midstream clean catch ("ideal"). Samples underwent standard automated urinalysis and culture. Urinalysis indices and culture contamination were compared.
  
  
  RESULTS
  The proportion of abnormal results from samples collected by "non-clean" vs. "ideal" technique, respectively, were: leukocyte esterase (>trace) 50%, 35% (95% confidence interval for difference -6% to 36%); nitrites (any) 2.5%, 2.5% (difference -2.5 to 2.5%); white blood cells (>5/high-powered field [HPF]) 50%, 27.5% (difference 4 to 41%); bacteria (any/HPF) 77.5%, 62.5%, (difference -7 to 37%); epithelial cells (>few) 65%, 30% (difference 13 to 56%); culture contamination (>1000 colony-forming units of commensal or >2 species) 77%, 63% (difference -5 to 35%). No urinalysis index was positively correlated with culture contamination.
  
  
  CONCLUSIONS
  Contemporary automated urinalysis indices were often abnormal in a disease-free population of women, even using ideal collection technique. In clinical practice, such false-positive results could lead to false-positive UTI diagnosis. Only urine nitrite showed a high specificity. Culture contamination was common regardless of collection technique and was not predicted by urinalysis results.
authors.affiliation: Department of Emergency Medicine, Oakland, California.
authors.forename: Bradley W
authors.initials: BW
authors.lastname: Frazee
authors.affiliation: Department of Emergency Medicine, Oakland, California.
authors.forename: Kayla
authors.initials: K
authors.lastname: Enriquez
authors.affiliation: Department of Pathology, Alameda Health System - Highland Hospital, Oakland, California.
authors.forename: Valerie
authors.initials: V
authors.lastname: Ng
authors.affiliation: Department of Emergency Medicine, Oakland, California.
authors.forename: Harrison
authors.initials: H
authors.lastname: Alter
mesh_terms: D000328:Adult; D002265:Carboxylic Ester Hydrolases / Q000032:analysis; D015169:Colony Count, Microbial; D018592:Cross-Over Studies; D004847:Epithelial Cells; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D009573:Nitrites / Q000032:analysis; D011446:Prospective Studies; D016482:Urinalysis; D014552:Urinary Tract Infections / Q000175:diagnosis* / Q000652:urine; D059349:Urine Specimen Collection / Q000379:methods*
chemical_list: D009573:Nitrites; C021443:leukocyte esterase; D002265:Carboxylic Ester Hydrolases
keywords: urinalysis; urinary tract infection