What is the next step in managing a patient with abnormal urinalysis results suggesting a possible urinary tract infection?

Management of Abnormal Urinalysis Results

The next step in managing a patient with this urinalysis showing elevated squamous epithelial cells and few bacteria is to obtain a new urine specimen via catheterization or clean-catch method for culture, as the current specimen likely represents contamination rather than a true urinary tract infection.

Interpretation of Current Urinalysis Results

The urinalysis shows:

• Normal color, appearance, specific gravity, pH
• Negative for glucose, bilirubin, ketones, blood, protein, nitrite, and leukocyte esterase
• No WBCs or RBCs seen
• Elevated squamous epithelial cells (10-20/HPF, reference range ≤5/HPF)
• Few bacteria

This pattern strongly suggests specimen contamination rather than a true UTI for the following reasons:

• The presence of elevated squamous epithelial cells (10-20/HPF) indicates contamination from the vagina in females or prepuce in uncircumcised males 1
• The absence of pyuria (no leukocyte esterase, no WBCs) with bacteria present suggests contamination rather than infection 2
• Both nitrite and leukocyte esterase tests are negative, which has a high negative predictive value for UTI 2

Next Steps in Management

1. Obtain a proper specimen:

   • For adults: Request a clean-catch midstream urine specimen after proper cleansing 1
   • For children: Obtain urine via catheterization or suprapubic aspiration 1
   • For women where vaginal contamination is likely: Consider catheterized specimen 1

2. Perform urinalysis and culture on the new specimen:

   • A properly collected specimen should be processed within 1 hour at room temperature or within 4 hours if refrigerated 1
   • Both urinalysis and culture are necessary for definitive diagnosis 2

3. Interpret results based on established criteria:

   • Diagnosis of UTI requires both:
     • Urinalysis showing pyuria and/or bacteriuria
     • Culture with ≥50,000 CFU/mL of a uropathogen 1, 2

Diagnostic Considerations

The combination of urinalysis findings is crucial for accurate interpretation:

• Leukocyte esterase has 83% sensitivity and 78% specificity for UTI 1, 2
• Nitrite testing has 53% sensitivity but 98% specificity 1, 2
• Combined testing (either positive) increases sensitivity to 93% 2

When interpreting results, remember:

• Negative dipstick tests (both leukocyte esterase and nitrite) have excellent negative predictive value 2
• Positive nitrite is highly specific for bacteriuria 2
• The presence of squamous epithelial cells indicates contamination 1

Common Pitfalls to Avoid

1. Don't treat based on contaminated specimens: Treating based on the current specimen would likely lead to unnecessary antibiotic use 3

2. Don't ignore specimen quality: A "positive" culture from a contaminated specimen cannot be used to document a UTI 1

3. Don't rely solely on dipstick testing: While useful for screening, dipstick testing alone is insufficient for definitive diagnosis 2

4. Don't confuse asymptomatic bacteriuria with UTI: Treatment decisions should be based on both symptoms and laboratory findings 2

In this case, the elevated squamous epithelial cells with few bacteria but no pyuria strongly suggests contamination rather than infection, necessitating a new, properly collected specimen before any treatment decisions are made.