From the Guidelines
The diagnostic workup for asymptomatic microcytic hematuria should begin with a thorough history and physical examination, followed by urinalysis confirmation with microscopic examination showing >3 red blood cells per high-power field on at least two separate occasions, as recommended by the American Urological Association 1.
Initial Evaluation
The initial evaluation should include:
- Complete blood count
- Serum creatinine
- Urine culture to rule out infection
- Upper tract imaging with CT urography or renal ultrasound to evaluate for kidney stones, masses, or structural abnormalities 1
Cystoscopy and Urine Cytology
Cystoscopy should be performed in all adults over 35 years old and in younger patients with risk factors for bladder cancer such as smoking history or chemical exposures 1. Urine cytology may be useful as an adjunct test, particularly in high-risk patients.
Follow-up Evaluation
If initial evaluation is negative, consider causes such as glomerular disease, which may require nephrology consultation and possibly kidney biopsy. For persistent hematuria with negative workup, follow-up evaluation should occur at 6,12, and 24 months with repeat urinalysis and possibly cystoscopy.
Importance of Comprehensive Approach
The comprehensive approach is necessary because while most cases are benign, asymptomatic microscopic hematuria can be the first sign of serious urological malignancies or kidney disease, with approximately 5-10% of cases revealing significant pathology 1. Key points to consider in the initial evaluation of asymptomatic microcytic hematuria include:
- Receipt of antiplatelet or anticoagulant therapy is not believed to be a satisfactory explanation for hematuria 1
- Routine cytologic evaluation of urine is no longer recommended in the initial evaluation, and urine markers approved by the U.S. Food and Drug Administration for bladder cancer detection may be useful in high-risk patients 1
From the Research
Diagnostic Workup for Asymptomatic Microcytic Hematuria
The diagnostic workup for asymptomatic microcytic hematuria typically involves a combination of tests to determine the underlying cause of the condition.
- The initial evaluation may include:
- Renal ultrasound (US) scanning
- Cystoscopy
- Urinalysis
- Urine culture
- Cytology 2
- If the initial evaluation is negative, patients may undergo re-evaluation after 3 months to check for persistence of microhematuria 2
- For patients with persistent microhematuria, upper urinary tract imaging may be recommended, which can be done using intravenous urography (IVU) 2 or multiphasic computed tomography urography 3
- Cystoscopy is also recommended to evaluate the lower urinary tract for urethral stricture disease, benign prostatic hyperplasia, and bladder masses 3
- Voided urine cytology is no longer recommended as part of the routine evaluation of asymptomatic microscopic hematuria, unless there are risk factors for malignancy 3
Guidelines for Evaluation and Management
There are various guidelines for the evaluation and management of asymptomatic microscopic hematuria, including those from the American Urological Association, Canadian Urological Association, and National Institute for Health and Care Excellence 4
- These guidelines recommend evaluation for asymptomatic microscopic hematuria in the absence of potential benign aetiologies, with the evaluation including cystoscopy and upper urinary tract imaging 4
- However, there is significant variation among current guidelines for asymptomatic microscopic hematuria with respect to who should be evaluated and in what manner 4
Risk Factors and Considerations
Certain risk factors, such as age, sex, and history of smoking, may increase the risk of urologic malignancy in patients with asymptomatic microscopic hematuria 3
- Patients with dysmorphic red blood cells, cellular casts, proteinuria, elevated creatinine levels, or hypertension in the presence of microscopic hematuria should prompt concurrent nephrologic and urologic referral 3