Can Urine Clarity Exclude the Diagnosis of Urinary Tract Infection?

Abstract

ABSTRACT. Objectives. To determine the association of clear urine by visual inspection with the absence of significant bacteruria, and to compare it with standard urinalysis.Methods. The study was performed in the emergency department of Children's Hospital Medical Center, Cincinnati, Ohio. It was a prospective, convenience sample of children <21 years of age who had catheterized or midstream clean-catch urine specimen collected for culture. Clinical findings including the presence or absence of fever, abdominal pain, dysuria, frequency, and urgency were collected for each patient. Urine was visually assessed for clarity by 2 independent observers using a standardized technique. Standard laboratory urinalysis and microscopy were also performed on all specimens. A positive urine culture was defined as >10 4 colony-forming unit (CFU)/mL of a urinary pathogen if obtained by catheterization and >10 5 CFU/mL if obtained by midstream.Results. Samples were obtained from 159 patients ranging in age from 4 weeks to 19 years. Females comprised 77% of the patients. One hundred ten of the samples (69%) were clear to visual inspection. There were a total of 29 positive cultures; however, 3 were in children with clear urine. The finding of clear urine on visual inspection had a negative predictive value of 97.3%. These results were similar to those obtained with standard urinalysis.Conclusion. Clear urine on visual inspection cannot completely eliminate the possibility that a child has a urinary tract infection. However, it is a reproducible test that offers the advantages of being simple, fast, and inexpensive. The finding of clear urine should be considered a reasonable and relatively effective bedside screen for the presence of a urinary tract infection. Pediatrics 2000;106(5). URL: http://www.pediatrics.org/ cgi/content/full/106/5/e60; urinary tract infection, child, urine clarity, urinalysis, diagnosis.ABBREVIATIONS. UTI, urinary tract infection; NPV, negative predictive value; ED, emergency department; LE, leukocyte esterase; WBC, white blood cell count; hpf, high-power field; CFU, colony-forming unit; MSU, midstream specimen. U rine specimens for urinalysis and culture are frequently obtained on pediatric patients suspected of having a urinary tract infection (UTI). A culture result of an appropriately obtained urine specimen is considered the gold standard for diagnosis of a UTI; however, these results require up to 24 hours to obtain. Investigators have tried using the urine dipstick, Gram stain, microscopy, and enhanced urinalysis for more rapid diagnosis, but none of these methods were capable of detecting all UTIs. [1][2][3][4][5][6] Because no rapid method can exclude a UTI with 100% certainty, most clinicians send all urine specimens for culture, irrespective of the findings on routine urinalysis.There are 2 studies that have examined the association of crystal clear urine with the absence of a UTI. 7,8 In the first study, the presence of clear urine had a negative predictive value (NPV) for the absence of UTI o...

Diagnostic test of urine clarity in urinary tract infection

“…Three previous studies had investigated the correlation between urine clarity and the absence of UTI. [9][10][11][12] Uncircumcised genital is a risk factor of UTI. In our study, there were 72.5% uncircumcised male subjects, which was consistent with Wiswell 13 that incidence of UTI decreased in circumcised men.…”

“…Urine clarity in UTI had high negative predictive value, between 96% and 100%, and it was able to be used to rule out the diagnosis of UTI. [9][10][11][12] The objective of this study was to identify the diagnostic value of urine clarity through a visual examination in children with UTI.…”

Urinary tract infections: diagnosis and management

“…A clear urine sample has been shown to have a negative predictive value (NPV) of 97 per cent for excluding urine infection. 9,10 However, visual appearance is prone to observer error and may not be a useful discriminator.…”

The point of view of the paediatric nuclear medicine physician Monica A Rossleigh

“…Urine culture is indicated if the child's urine is cloudy or if the dipstick test shows positive leukocyte esterase or nitrite activity. [13][14][15][16] Urine culture also is recommended for children with recurrent symptoms.…”