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Question clinique
Does the presence of squamous epithelial cells decrease the accuracy of urinalysis?
L’Essentiel
This study confirms both what we were taught and what we have observed in our own practices: The presence of squamous epithelial cells makes the interpretation of urine cultures less accurate. 2b
Référence
Plan de l'etude: Cohort (retrospective)
Financement: Government
Cadre: Emergency department
Sommaire
These authors examined the records of 6490 patients who had a urine culture and a contemporaneous urinalysis performed in a single emergency department over a 26-month period. The authors included all samples, regardless of collection method. They classified a urine culture as positive when they detected at least 10^4 colony-forming units (CFUs) of pathogenic bacteria, negative when they detected no growth, or contaminated for all other results (including a growth of fewer than 10^4 CFUs pathogenic organisms, mixed growth of multiple bacterial species in any concentration, or any growth of nonpathogenic organisms). Although these classifications are well-grounded in the literature, there is a bit of noise as to the number of CFUs and method of collection. Women composed approximately 48% of the total panel, but 74% of the samples with more than 5 squamous epithelial cells (SECs) came from women. Additionally, patients with more than 5 SECs were younger (50.2 vs 54.6 years of age) and had a higher body mass index (29.2 vs 27.9) than those with 5 or fewer SECs. Overall, 19.2% of all samples grew more than 10^4 pathogens and 21.6% were contaminated. When more than 5 SECs were present, 21.4% of the cultures were positive and 44.5% were contaminated. The authors then performed a bunch of statistical jujitsu that basically indicated that urine chemistry and microscopy all performed better when SECs were absent. The "good" news is that leukocyte esterase activity didn't perform all that well regardless of the presence or absence of SECs and the presence of nitrites remained fairly specific independent of SECs.
Reviewer
Henry C. Barry, MD, MS
Professor
Michigan State University
East Lansing, MI
Commentaires
Relationship between urinalysis and positive urine cultures.
Leukocyte esterase activity less reliable regardless of the presence or absence of squamous epithelial cells. The presence of nitrites remained fairly specific independent of SECs.
gunk in urine
the presence of nitrates still is the single most reliable indicator on the urine stick.
As expected
As expected
Schmutz in the Urine
A nice, folksy read. Good job, doctor! JV
Thanks for the laugh
"Schmutz". That is all.