Should a patient with a single episode of microscopic hematuria (presence of red blood cells in urine) undergo a full evaluation or have a repeat urinalysis?

From the Guidelines

A single bout of microscopic hematuria should be fully evaluated rather than simply repeating the urinalysis, as recommended by the American Urological Association (AUA) and Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction (SUFU) guideline published in 2020 1. The evaluation should include a detailed medical history, physical examination, and additional testing such as urine culture, imaging studies, and possibly cystoscopy. This comprehensive approach is recommended because microscopic hematuria can be a sign of serious underlying conditions including urinary tract malignancies, kidney disease, or urinary stones, even when it occurs just once.

• Key factors to consider in the evaluation include:
  • Age, with adults over 35 years old being at higher risk for underlying malignancy
  • Smoking history and occupational exposures, which increase the risk of urothelial cancer
  • Degree and persistence of microhematuria, with 3 or more red blood cells per high-power field on microscopic examination of urinary sediment defining microhematuria
  • Prior gross hematuria, which may indicate a higher risk for genitourinary malignancy According to the AUA/SUFU guideline, a risk classification system should be used to stratify patients as low-, intermediate-, or high-risk for genitourinary malignancy, and diagnostic evaluation with cystoscopy and upper tract imaging should be recommended according to patient risk and involving shared decision-making 1.
• The guideline also recommends repeating urinalysis following resolution of a gynecologic or non-malignant genitourinary cause of microhematuria, but this does not preclude the need for a thorough initial evaluation to rule out more serious conditions. In clinical practice, delaying evaluation risks missing significant pathology, and prompt evaluation is particularly important in higher-risk populations.

From the Research

Evaluation of Microscopic Hematuria

• Microscopic hematuria is a common finding on routine urinalysis of adults, and its evaluation is crucial to determine the underlying cause 2, 3.
• The exact definition of microscopic hematuria is debated, but it is generally defined as > 3 red blood cells/high power microscopic field 2.
• The causes of hematuria are extensive, and the most common differential diagnosis for both microscopic and gross hematuria in adults includes infection, malignancy, and urolithiasis 2.

Approach to Evaluation

• In patients with suspected microscopic hematuria, urine dipstick testing may suggest the presence of blood, but results should be confirmed with a microscopic examination 4.
• The evaluation of microscopic hematuria should include renal function testing, urinary tract imaging, and cystoscopy in the absence of obvious causes 4.
• Patients with proteinuria, red cell casts, and elevated serum creatinine levels should be referred promptly to a nephrology subspecialist 3.
• Microscopic hematuria with signs of urinary tract infection should resolve with appropriate treatment of the underlying infection 3.

Repeat Analysis and Referral

• Persistent microscopic hematuria indicates the presence of a renal disease that warrants close monitoring and evaluation 5.
• Prompt referral to a pediatric nephrologist is indicated in situations when hematuria does not resolve within 2 weeks of onset of glomerulonephritis, there is a need for a renal biopsy, in the presence of persistent microscopic hematuria, and need for specific urine biochemistry testing or imaging studies 5.
• Patients who have no identifiable cause after an extensive workup should be monitored for early detection of malignancy or occult renal disease 2.