From the Guidelines
Hematuria, or blood in the urine, is an indication for further evaluation to determine the underlying cause, and clinicians should confirm heme-positive results of dipstick testing with microscopic urinalysis that demonstrates 3 or more erythrocytes per high-powered field before initiating further evaluation in all asymptomatic adults. The presence of red blood cells (RBCs) in the urine, either visible to the eye (macroscopic hematuria) or as viewed under the microscope (microscopic hematuria), is a common finding in clinical practice and can sometimes be a sign of occult cancer or other underlying conditions 1.
Key Points to Consider
- The clinical evaluation of patients with any form of hematuria begins with a meticulous history and thorough evaluation of the urine 1.
- The need for imaging evaluation depends on the clinical scenario in which hematuria presents, including the suspected etiology 1.
- Ultrasound and CT are the most common imaging methods used to assess hematuria in children, although other imaging modalities may be appropriate in certain instances 1.
- Clinicians should consider urology referral for cystoscopy and imaging in adults with microscopically confirmed hematuria in the absence of some demonstrable benign cause 1.
- Clinicians should pursue evaluation of hematuria even if the patient is receiving antiplatelet or anticoagulant therapy 1.
Recommendations
- Clinicians should include gross hematuria in their routine review of systems and specifically ask all patients with microscopic hematuria about any history of gross hematuria 1.
- Clinicians should not use screening urinalysis for cancer detection in asymptomatic adults 1.
- Clinicians should refer for further urologic evaluation in all adults with gross hematuria, even if self-limited 1.
It's essential to note that false positives can occur due to certain foods, medications, or menstruation in women, so these factors should be considered when interpreting results 1. If blood is detected in a urinalysis, further investigation is usually necessary to determine the underlying cause.
From the Research
Indication of Hematuria in Urinalysis
The presence of blood in the urine, known as hematuria, can be an indication of various underlying conditions. According to 2, 3, 4, 5, 6, hematuria can be detected through urinalysis, which includes dipstick testing and microscopic examination.
Detection Methods
- Dipstick testing: a common screening test for hematuria, which can detect the presence of blood in the urine 2, 4
- Microscopic urinalysis: a more accurate method for detecting and quantifying hematuria, which can distinguish between glomerular and nonglomerular sources of bleeding 2, 3
Evaluation and Diagnosis
- Once hematuria is detected, a comprehensive history, physical examination, laboratory studies, and radiographic imaging may be necessary to investigate its etiology 2
- The evaluation of microscopic hematuria should include renal function testing, urinary tract imaging, and cystoscopy 3, 5
- The American Urological Association has published guidelines for the management of asymptomatic microscopic hematuria, which recommend a diagnostic workup for patients with persistent hematuria or risk factors for malignancy 5
Significance of Hematuria
- Hematuria can be a sign of significant underlying conditions, such as urinary tract infection, urolithiasis, malignancies, benign prostatic hyperplasia, and nephropathies 6
- The presence of 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 5