For a patient with a kidney stone and hematuria, should I order a urine dipstick or a urinalysis with reflex to culture?

Order Urinalysis with Reflex to Culture

For your patient with a kidney stone and hematuria returning for follow-up, you should order a urinalysis with reflex to culture rather than a simple urine dipstick. 1

Rationale Based on AUA Guidelines

The American Urological Association explicitly states that urinalysis should include both dipstick and microscopic evaluation to assess urine pH, identify indicators of infection, and detect crystals that may indicate stone type. 1 A simple dipstick alone is insufficient for proper evaluation of kidney stone patients.

When to Add Urine Culture

Urine culture should be obtained if the urinalysis suggests urinary tract infection (presence of pyuria, positive leukocyte esterase, or positive nitrite) or if the patient has clinical signs of infection. 1 The reflex approach is ideal because:

• It automatically triggers culture only when pyuria (≥10 WBCs/high-power field) or positive leukocyte esterase/nitrite is detected 1
• This prevents unnecessary cultures in patients without infection while ensuring appropriate testing when infection is present 1
• It reduces overtreatment of asymptomatic bacteriuria, which is common but does not require antibiotics 2, 3

Critical Considerations for Hematuria Follow-Up

Confirm True Microscopic Hematuria

Since your patient had blood in the urine during the acute stone episode, you must verify with microscopic urinalysis showing ≥3 red blood cells per high-power field to confirm true hematuria. 4, 5 A positive dipstick alone has limited specificity (65-99%) and requires microscopic confirmation. 4, 5

Post-Treatment Hematuria Evaluation

If hematuria persists after the stone has passed or been treated, proceed with full hematuria evaluation including urologic referral, especially if the patient has risk factors for malignancy. 4 Risk factors include:

• Age >40 years 4
• Smoking history 4
• Occupational chemical exposures 4
• History of gross hematuria 4

If hematuria resolves after stone passage, no additional cancer evaluation is necessary. 4 However, repeat urinalysis 6 weeks after resolution to confirm clearance. 4

Common Pitfalls to Avoid

• Never assume hematuria is solely from the kidney stone without confirming resolution after stone passage 4
• Do not skip microscopic confirmation if ordering only a dipstick—this misses critical diagnostic information about pyuria, crystals, and true RBC count 1, 5
• Do not obtain urine culture without first checking urinalysis—this leads to overdiagnosis of asymptomatic bacteriuria and unnecessary antibiotic use 1, 2

Practical Algorithm for Your Patient

1. Order urinalysis with reflex to culture 1
2. Review microscopy for:
   • RBC count to confirm hematuria resolution or persistence 4, 5
   • WBC count and bacteria to assess for infection 1
   • Crystal type to guide stone prevention strategies 1
3. If pyuria or positive leukocyte esterase/nitrite: Culture will automatically be performed and antibiotic therapy guided by results 1
4. If hematuria persists (≥3 RBCs/hpf) after stone resolution: Consider urologic referral based on risk factors 4
5. If hematuria resolved: Proceed with metabolic stone evaluation and prevention strategies as indicated 1