Can a menstrual period cause microscopic hematuria?

Menstruation as a Cause of Microscopic Hematuria

Yes, menstruation can cause microscopic hematuria, and patients without risk factors who have microhematuria attributed to menstruation do not require a complete imaging workup if the hematuria resolves after menstruation. 1

Benign Causes of Microscopic Hematuria

• Menstruation is recognized as one of several benign causes of microscopic hematuria, along with vigorous exercise, infection, trauma, and recent urologic procedures 1
• When microscopic hematuria is suspected to be due to menstruation, a repeat urinalysis should be performed 48 hours after cessation of menstruation 1
• If the hematuria resolves after menstruation ends, no additional evaluation is warranted 1, 2

Proper Sample Collection

• In women, obtaining a clean-catch urine specimen may be difficult during menstruation due to vaginal contamination 1, 2
• A catheterized urinary specimen is indicated if a clean-catch specimen cannot be reliably obtained during menstruation 1, 2
• Urethral and vaginal examinations should be performed in women to exclude local causes of microscopic hematuria 1

Evaluation Algorithm for Persistent Hematuria

If hematuria persists after menstruation:

1. Initial Assessment:

   • Determine if hematuria is persistent (≥3 red blood cells per high-power field) 3, 2
   • Assess for risk factors for urologic malignancy (age >35 years, smoking history, occupational exposures) 1

2. For Persistent Hematuria:

   • Complete urologic evaluation including examination of urinary sediment, testing for proteinuria and urinary tract infection 1, 2
   • Radiologic imaging of the upper urinary tract and cystoscopic examination may be necessary 1, 3

Risk Stratification

• Microscopic hematuria has a low risk of malignancy (2.6% to 4%) compared to gross hematuria (30% to 40%) 1
• In most patients with asymptomatic microscopic hematuria, a cause is never found 1, 4
• Approximately 80% of patients with asymptomatic hematuria have "idiopathic microscopic hematuria" without an obvious underlying medical condition 4

Common Pitfalls to Avoid

• Do not assume that menstruation is the cause of hematuria without proper verification through repeat testing after menstruation 1, 2
• Do not neglect evaluation of persistent hematuria even if there is a potential benign cause like menstruation 3, 2
• Be aware that contamination from vaginal bleeding during menstruation can produce false-positive results for hematuria 1, 2

By following this approach, clinicians can appropriately manage patients with microscopic hematuria potentially caused by menstruation while ensuring that persistent hematuria receives proper evaluation.