From the Guidelines
Red blood cells (RBCs) in urine, also called hematuria, requires immediate medical evaluation as it may indicate an underlying health issue, and patients should schedule an appointment with their healthcare provider promptly. While waiting for the appointment, increasing fluid intake can help flush the urinary system. The doctor will likely order urinalysis, blood tests, and possibly imaging studies like ultrasound or CT scan to determine the cause. Common causes include urinary tract infections (treated with antibiotics like nitrofurantoin or trimethoprim-sulfamethoxazole for 3-7 days) 1, kidney stones (managed with pain medication and increased fluids), enlarged prostate in men (treated with medications like tamsulosin), or more serious conditions like kidney disease or cancer.
Key Considerations
- Hematuria is characterized as either microhematuria or gross hematuria, with microhematuria defined as three or more red blood cells per high power field on microscopic evaluation of urinary sediment 1.
- The presence of RBCs in urine is not normal, even in small amounts, and should never be ignored, as early diagnosis of the underlying cause can prevent complications and improve treatment outcomes.
- Patients with suspected urinary tract infection as a cause of microhematuria should have urine cultures performed, preferably before antibiotic therapy, to confirm an infection 1.
- A thorough history, physical examination, urinalysis, and serologic testing should be performed prior to any initial imaging, and many patients should undergo cystoscopy in addition to any imaging evaluation 1.
Evaluation and Management
- The need for imaging evaluation depends on the clinical scenario in which hematuria presents, including the suspected etiology, and ultrasound and CT are the most common imaging methods used to assess hematuria 1.
- Patients with proteinuria, dysmorphic RBCs, cellular casts, or renal insufficiency may have medical renal disease, which can cause hematuria, and should be referred to a nephrologist 1.
- Examination of the urinary sediment is an essential tool for the nephrologist with an interest in glomerular disease, and all attempts should be made to allow routine performance and teaching of this skill 1.
Recommendations
- All patients with gross hematuria should have a full urologic workup, as it has a high association with malignancy of up to 30% to 40% 1.
- Patients with microhematuria have a low risk of malignancy ranging from 2.6% to 4%, and, in most patients with asymptomatic microhematuria, a cause is never found 1.
- Clinicians should refer patients with microhematuria for nephrologic evaluation if medical renal disease is suspected, but risk-based urologic evaluation should still be performed 1.