What is the interpretation of a urinalysis with positive nitrites, small leukocyte esterase, mild leukocyturia, few epithelial cells, and significant bacteriuria?

Interpretation of Urinalysis with Positive Nitrites, Small Leukocyte Esterase, and Bacteriuria

This urinalysis strongly indicates a urinary tract infection (UTI) requiring antibiotic treatment based on the combination of positive nitrites, leukocyte esterase, and significant bacteriuria. 1

Diagnostic Significance of Individual Findings

High-Specificity Markers

• Positive nitrites: Highly specific (98%) for UTI, indicating the presence of bacteria that convert nitrates to nitrites 1
• Bacteriuria (>20 bacteria/HPF): Strong indicator of infection, especially when combined with other positive markers 1

Supporting Markers

• Small leukocyte esterase: Indicates pyuria with sensitivity of 83% for UTI 1
• WBCs (4-6/HPF): Represents mild pyuria, consistent with inflammatory response to infection 2
• Epithelial cells (4-6): Moderate contamination but doesn't invalidate other positive findings 3

Interpretation Algorithm

1. Assess high-specificity markers:

   • Positive nitrites have excellent specificity (98%) 1
   • Significant bacteriuria (>20/HPF) strongly supports infection

2. Evaluate supporting evidence:

   • Presence of leukocyte esterase (even small) increases probability of UTI
   • WBCs 4-6/HPF represent mild pyuria consistent with UTI

3. Consider specimen quality:

   • Moderate epithelial cells (4-6) indicate some contamination
   • However, epithelial cells reduce but don't eliminate diagnostic accuracy 3
   • The presence of both nitrites and leukocyte esterase maintains high specificity despite contamination 1

Clinical Implications

• Diagnostic conclusion: This urinalysis is consistent with UTI despite moderate specimen contamination 1
• Next steps: Urine culture should be obtained to confirm infection and guide targeted antibiotic therapy 2
• Treatment consideration: Empiric antibiotic therapy is appropriate while awaiting culture results due to the high probability of infection 1

Important Caveats

• Specimen quality matters: The moderate epithelial cell count (4-6) suggests some contamination, which reduces but doesn't eliminate diagnostic accuracy 3
• False positives: Epithelial cells are associated with higher false-positive rates for leukocyte esterase and WBCs, but nitrites maintain high specificity regardless 3
• Clinical correlation required: Always interpret urinalysis in context of symptoms; asymptomatic bacteriuria generally doesn't require treatment except in specific populations (pregnancy, pre-urologic procedures) 1
• Avoid overdiagnosis: In asymptomatic patients, even with positive urinalysis findings, consider whether this represents asymptomatic bacteriuria rather than true infection 4

This urinalysis demonstrates multiple markers consistent with UTI, with positive nitrites being particularly specific. While the moderate epithelial cell count indicates some contamination, the combination of findings strongly supports a diagnosis of UTI.