Can menstruation cause microscopic hematuria (presence of blood in urine)?

Menstruation as a Cause of Microscopic Hematuria

Yes, menstruation can cause microscopic hematuria, and if hematuria resolves after menstruation ends, no additional evaluation is warranted.

Understanding Microscopic Hematuria and Benign Causes

Microscopic hematuria is defined as three or more red blood cells per high-power field on microscopic evaluation of urinary sediment from properly collected specimens 1. While microscopic hematuria can be a sign of urinary tract malignancy, there are several benign causes that should be excluded before proceeding with extensive evaluation.

The American Urological Association and American College of Radiology guidelines specifically identify menstruation as one of the benign causes of microscopic hematuria, along with:

• Vigorous exercise
• Sexual activity
• Trauma
• Recent urologic procedures
• Infection 1, 2

Management Algorithm for Menstruation-Related Hematuria

1. Initial detection of microscopic hematuria during menstruation:

   • Document timing in relation to menstrual cycle
   • Avoid collecting urine samples during active menstruation when possible

2. Repeat testing approach:

   • Wait at least 48 hours after cessation of menstruation
   • Repeat urinalysis 1
   • If hematuria resolves, no additional evaluation is necessary

3. For persistent hematuria after menstruation:

   • Proceed with standard hematuria evaluation including:
     • Upper urinary tract imaging
     • Cystoscopy (particularly if risk factors are present)
     • Urine cytology if indicated

Risk Stratification for Women with Microscopic Hematuria

The risk of urinary tract malignancy is significantly lower in women than in men 3. Key risk factors that warrant more thorough evaluation include:

• Age over 60 years
• History of smoking
• Gross hematuria (visible blood)
• More than 25 red blood cells per high-power field 3

For low-risk women (younger than 50 years, never-smokers, without gross hematuria, and fewer than 25 RBCs per high-power field), the risk of urinary tract malignancy is ≤0.5% 3.

Common Pitfalls in Hematuria Evaluation

1. Over-evaluation of transient hematuria:

   • Performing extensive workups for hematuria that resolves after menstruation ends
   • Subjecting patients to unnecessary radiation exposure through CT urography

2. Under-evaluation of persistent hematuria:

   • Assuming hematuria is due to menstruation without confirmation through repeat testing
   • Failing to evaluate persistent hematuria even after menstruation has ended

3. Specimen collection issues:

   • Collecting urine samples during active menstruation without proper technique
   • Not using catheterized specimens when clean-catch specimens cannot be reliably obtained due to vaginal contamination 1

Key Practice Points

• Menstruation is a recognized benign cause of microscopic hematuria 1, 2
• Repeat urinalysis 48 hours after cessation of menstruation is the appropriate next step 1
• If hematuria resolves after menstruation ends, no additional evaluation is needed
• Persistent hematuria after menstruation warrants standard evaluation
• Consider risk factors (age, smoking history, degree of hematuria) when determining the extent of evaluation needed 3

Research shows that many cases of hematuria are not fully evaluated according to guidelines 4, but it's equally important to avoid unnecessary testing when a benign cause like menstruation has been identified and confirmed through appropriate follow-up testing.