From the Guidelines
Gross hematuria warrants a more urgent and comprehensive evaluation, including immediate imaging and cystoscopy, due to its high association with malignancy, whereas microscopic hematuria may allow for a more measured approach, but still requires thorough workup and consideration of risk factors. Hematuria, whether gross or microscopic, requires medical evaluation as it may indicate underlying urinary tract pathology 1. The distinction between gross and microscopic hematuria is crucial, as gross hematuria has a high association with malignancy, ranging from 30% to 40%, and thus necessitates a full urologic workup 1. On the other hand, microscopic hematuria has a lower risk of malignancy, ranging from 2.6% to 4%, but still requires evaluation to rule out underlying conditions 1.
The evaluation of hematuria should include a thorough history, physical examination, urinalysis, and serologic testing, with cystoscopy and imaging considered based on the presence of risk factors and symptoms 2. The American Urological Association defines microhematuria as three or more red blood cells per high power field on microscopic evaluation of urinary sediment, and this definition guides the evaluation approach 1. Patients with gross hematuria should undergo a full urologic workup, including cystoscopy and upper tract imaging, whereas patients with microscopic hematuria may require a more tailored approach, considering their individual risk factors and symptoms 2.
Key considerations in the evaluation of hematuria include the presence of risk factors such as smoking, chemical exposure, or family history of urologic malignancies, which increase concern for both gross and microscopic hematuria 1, 3. The American College of Physicians advises against screening urinalysis for cancer detection in asymptomatic adults and recommends confirming heme-positive results with microscopic urinalysis before initiating further evaluation 3. Ultimately, a thorough and timely evaluation of hematuria is crucial to detect underlying conditions, particularly malignancies, and improve patient outcomes.
From the Research
Gross vs Micro Hematuria Implications
The implications of gross and micro hematuria differ in terms of their potential causes and recommended evaluation approaches.
- Gross hematuria is associated with a higher risk of malignancy, with a risk greater than 10% 4, and therefore warrants prompt urologic referral.
- Microscopic hematuria, on the other hand, most commonly has benign causes, such as urinary tract infection, benign prostatic hyperplasia, and urinary calculi 4.
Evaluation Approaches
The evaluation approaches for gross and micro hematuria also differ:
- Gross hematuria requires a thorough history and physical to determine potential causes and assess risk factors for malignancy 4.
- Microscopic hematuria requires laboratory tests to rule out intrinsic renal disease, imaging of the urinary tract, and referral to nephrology and urology subspecialists if no benign cause is found 4.
Risk Factors and Recommendations
Certain risk factors, such as age and history of cigarette use, can influence the recommended evaluation approach for microscopic hematuria:
- Older patients (> 40 years) and those with a history of cigarette use or occupational exposure should undergo upper tract imaging, cystourethroscopy, and cytologic examination of the urine 5.
- The American Urological Association recommends complete urologic evaluation for all patients with microscopic hematuria who are over 40 years of age, and younger patients with a history suspicious for urologic disease 5. Note that study 6 is not relevant to the topic of gross vs micro hematuria implications.