From the Guidelines
Gross and micro hematuria imply potential urinary tract pathology, ranging from benign to serious conditions, and warrant thorough evaluation to rule out underlying malignancies or other significant conditions. Hematuria can be classified as either gross or microscopic, with gross hematuria being visible blood in the urine and microscopic hematuria being detectable only through laboratory testing, typically defined as more than 3 red blood cells per high-power field on urinalysis 1. The causes of hematuria can vary, including urinary tract infections, kidney stones, trauma, strenuous exercise, certain medications, and more concerning conditions like urinary tract malignancies, glomerular diseases, or bleeding disorders.
Some key points to consider in the evaluation of hematuria include:
- Gross hematuria has a high association with malignancy, with a risk of up to 30% to 40%, and therefore warrants a full urologic workup 1.
- Microhematuria 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 detailed history, physical examination, urinalysis, urine culture, imaging studies, and possibly cystoscopy, especially in adults over 35 years with risk factors for urological malignancies 1.
- The presence of associated symptoms like pain, fever, or weight loss can help narrow the differential diagnosis and guide management.
According to the most recent guidelines, patients with gross hematuria should undergo a full urologic workup, including cystoscopy and upper tract imaging, while patients with microhematuria should be evaluated based on their risk classification, with low-risk patients potentially undergoing less extensive evaluation 1. It is essential to note that the evaluation of hematuria should be individualized, taking into account the patient's risk factors, symptoms, and medical history.
From the Research
Definition and Classification of Hematuria
- Hematuria is classified as either gross or microscopic 2, 3
- Gross hematuria implies a higher risk of malignancy, with a risk greater than 10% 2
- Microscopic hematuria most commonly has benign causes, such as urinary tract infection, benign prostatic hyperplasia, and urinary calculi 2
Causes and Evaluation of Hematuria
- The causes of hematuria are extensive, but the most common differential diagnosis for both microscopic and gross hematuria in adults includes infection, malignancy, and urolithiasis 3
- Clinical evaluation of patients with hematuria often involves urological consultation with urine cytology, urine culture, imaging studies, and cystoscopy 3, 4
- Patients who have no identifiable cause after an extensive workup should be monitored for early detection of malignancy or occult renal disease 3
Investigation and Management of Hematuria
- Recommended investigations for hematuria include computed tomography intravenous pyelogram, urine cytology, urine microscopy and culture, and blood tests 4
- Patients with risk factors for genitourinary malignancy, macroscopic hematuria, or those in whom no cause is found, should be referred to a urological service for further investigation including cystoscopy 4
- The yield of CT urography for upper urinary tract malignancy is low, and its use should be guided by American Urological Association criteria 5