From the Guidelines
The next step in managing a patient with persistent microscopic hematuria is to conduct a comprehensive evaluation to determine the underlying cause, starting with a detailed medical history and physical examination, followed by laboratory tests and imaging studies as necessary, as recommended by the most recent guidelines 1.
Initial Evaluation
This evaluation should begin with a thorough history, physical examination, urinalysis, and serologic testing prior to any initial imaging, as suggested by the American College of Radiology 1. The definition of microscopic hematuria is three or more red blood cells per high-power field on microscopic evaluation of urinary sediment from two of three properly collected urinalysis specimens, as defined by the American Urological Association 1.
Risk Factors and Further Evaluation
For patients over 35 years old or those with risk factors for urological malignancies, such as smoking history, chemical exposures, or prior pelvic radiation, a more thorough evaluation including a CT urogram or cystoscopy should be performed to rule out urological cancers, as advised by the American College of Physicians 1. The use of anticoagulant therapy does not alter the urologic evaluation of microhematuria, according to the American College of Radiology 1.
Imaging and Referral
Imaging studies are essential, typically starting with renal ultrasound to evaluate the kidneys and bladder. If these investigations suggest glomerular disease as the source of bleeding, referral to a nephrologist for possible kidney biopsy may be warranted. It's also important to address modifiable risk factors such as smoking cessation and blood pressure control throughout this process.
Key Considerations
- Microscopic hematuria can indicate various conditions ranging from benign causes like urinary tract infections to serious pathologies such as malignancies or glomerular diseases.
- Proper identification of the cause determines appropriate treatment.
- The evaluation should be tailored based on the presence of risk factors and the initial findings, with a focus on ruling out malignancy and other significant conditions, as emphasized by the American College of Radiology 1 and the American College of Physicians 1.
From the Research
Next Steps in Managing Microscopic Hematuria
The presence of blood in urine, known as hematuria, can be either microscopic or gross. Microscopic hematuria requires further investigation to determine its cause. The following steps can be taken:
- A thorough history and physical examination to determine potential causes and assess risk factors for malignancy 2
- Laboratory tests to rule out intrinsic renal disease 2
- Imaging of the urinary tract, such as multiphasic computed tomography urography, to identify hydronephrosis, urinary calculi, and renal and ureteral lesions 3
- Referral to nephrology and urology subspecialists for further evaluation and management 2, 3
- Cystoscopy to evaluate the lower urinary tract for urethral stricture disease, benign prostatic hyperplasia, and bladder masses 3
Factors to Consider
When evaluating microscopic hematuria, the following factors should be considered:
- Age: older patients are at higher risk for urologic malignancy 3, 4
- Number of red blood cells per high-power field: patients with <5 RBCs/HPF on three urinalyses are unlikely to have significant pathology 4
- Presence of proteinuria, cellular casts, or dysmorphic red blood cells: these findings should prompt concurrent nephrologic and urologic referral 3
- History of smoking: increases the risk of urologic malignancy 3
Diagnostic Tests
The following diagnostic tests can be used to evaluate microscopic hematuria:
- Urine culture: to rule out urinary tract infection 5, 3
- Urine cytology: no longer recommended as part of the routine evaluation of asymptomatic microscopic hematuria, unless there are risk factors for malignancy 3
- Computed tomography urography: to evaluate the upper urinary tract for hydronephrosis, urinary calculi, and renal and ureteral lesions 3, 4
- Cystoscopy: to evaluate the lower urinary tract for urethral stricture disease, benign prostatic hyperplasia, and bladder masses 3, 4