Practice Guidelines

Microscopic Hematuria in Adults: Updated Recommendations from the American Urological Association

 

Am Fam Physician. 2021 Dec ;104(6):655-657.

Author disclosure: No relevant financial affiliations.

Key Points for Practice

• Consider repeating urinalysis in women found to have microscopic hematuria associated with UTI following successful treatment.

• With microscopic hematuria in patients at low risk of cancer, performing repeat urinalysis at six months is a reasonable alternative to imaging and cystoscopy.

• Although gross hematuria is strongly associated with malignancy, microscopic hematuria is more common and has a lower malignancy risk.

From the AFP Editors

Previous guidelines from the American Urological Association (AUA) recommended that all patients with microscopic hematuria be fully evaluated for urinary tract cancer without regard to the patient's risk of malignancy. Although this strategy results in the fewest missed cancers in modeling studies, it is costly, increases patient risk, and can result in overdiagnosis. The AUA released an updated guideline for risk-based evaluation of microscopic hematuria.

Defining Microscopic Hematuria

The AUA defines microscopic hematuria as three or more red blood cells per high-power field (RBC/HPF) on urine microscopy. A threshold between three and 10 RBC/HPF has the highest sensitivity for detecting bladder cancer and the lowest negative likelihood ratio. A single urinalysis is sufficient because 95% of microscopic hematuria is detected in one sample. Because at least 20% of positive dipstick tests for blood have no red blood cells on subsequent urine microscopy, any positive dipstick should be confirmed.

Initial Evaluation

Initial evaluation for patients with microscopic hematuria involves searching for a likely cause to be addressed. Common causes include urinary tract infections (UTIs), menstruation, external genital lesions, vaginal atrophy, pelvic organ prolapse, urolithiasis, benign prostatic enlargement, and urethral stricture. After addressing any of these issues, a repeat urinalysis should be performed. With conditions such as prostatic hypertrophy, vaginal atrophy, and pelvic organ prolapse, microscopic hematuria may not completely resolve. In these cases, full evaluation may be warranted. Obtaining a catheter urine sample also may be helpful.

Women with urologic malignancies are often treated repeatedly for UTI before cancer is diagnosed. Repeating urinalysis with microscopy after identifying hematuria associated with UTI should be considered, although this strategy has not been prospectively validated.

Anticoagulation does not appear to explain microscopic hematuria, and the appropriate workup should be performed in these patients. Patients taking antithrombotic medications are more likely to be diagnosed with bladder cancer, suggesting these medications may increase bleeding from underlying malignancies.

Risk Stratification

If the initial evaluation suggests no obvious source of microscopic hematuria, possible risk factors should be assessed. Smoking, higher numbers of RBC/HPF, persistent hematuria, and history of gross hematuria increase the risk of malignancy (Table 1).

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TABLE 1.

American Urological Association Microhematuria Risk Stratification System

Low (patient meets all criteria)

Men age < 40 years; women age < 50 years

3 to 10 RBC/HPF on a single urinalysis

Never smoker or < 10 pack-years

No risk factors for urothelial cancer

Intermediate (patient meets any one of these criteria)

Men age 40 to 59 years; women age 50 to 59 years

11 to 25 RBC/HPF on a single urinalysis

10 to 30 pack-years

Low-risk patient with no prior evaluation and 3 to 10 RBC/HPF on repeat urinalysis

Additional risk factors for urothelial cancer

High (patient meets any one of these criteria)

Women or men age 60 years

> 25 RBC/HPF on a single urinalysis

> 30 pack-years

History of gross hematuria


RBC/HPF = red blood cells per high-power field.

Reprinted with permission from Barocas DA, Boorjian SA, Alvarez RD, et al. Microhematuria: AUA/SUFU guideline. J Urol. 2020;204(4):783.

TABLE 1.

American Urological Association Microhematuria Risk Stratification System

Low (patient meets all criteria)

Men age < 40

Author disclosure: No relevant financial affiliations.

Coverage of guidelines from other organizations does not imply endorsement by AFP or the AAFP.

This series is coordinated by Michael J. Arnold, MD, contributing editor.

A collection of Practice Guidelines published in AFP is available at https://www.aafp.org/afp/practguide.

 

 

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