From the Guidelines
For trace blood found in urinalysis on two separate occasions, I recommend a stepwise evaluation starting with a repeat urinalysis with microscopy to confirm the finding, as suggested by the American College of Radiology 1 and the European Association of Urology Guidelines Office 1.
Initial Evaluation
If confirmed, obtain a comprehensive history focusing on:
- Medication use (especially NSAIDs, anticoagulants)
- Recent exercise
- Menstruation in females
- Symptoms of urinary tract infection or kidney stones Physical examination should include:
- Vital signs
- Abdominal examination
- Costovertebral angle tenderness assessment Laboratory tests should include:
- Complete blood count
- Comprehensive metabolic panel
- Urine culture
Further Evaluation
If these initial evaluations are unrevealing, consider renal ultrasound to assess for structural abnormalities, stones, or masses, as recommended by the Journal of the American College of Radiology 1. For persistent unexplained hematuria, especially in patients over 35 years or with risk factors for urological malignancies, referral to urology for cystoscopy is appropriate, as highlighted by the European Urology study 1. In younger patients without risk factors and normal imaging, consider nephrology referral to evaluate for glomerular causes. This systematic approach is necessary because microscopic hematuria, even if intermittent or trace, can be the first sign of significant urological or nephrological conditions including malignancies, stones, glomerulonephritis, or interstitial nephritis, though benign causes like vigorous exercise or certain medications are also possible, as noted by the Annals of Internal Medicine study 1.
From the Research
Work-Up for Trace Blood Found in Urine Analysis (U/A) x 2
- The presence of blood in the urine, either on voiding or in a catheterized specimen, is defined as hematuria 2, 3.
- Hematuria is broadly divided into microscopic and gross hematuria and may be symptomatic or asymptomatic 3.
- The work-up for hematuria includes laboratory tests to rule out intrinsic renal disease, imaging of the urinary tract, and referral to nephrology and urology subspecialists 2.
- Imaging techniques that are useful for diagnosis include plain X-rays of the kidney, ureter, and bladder; ultrasound; intravenous urography; computed tomography (CT); magnetic resonance imaging; retrograde ureterography and pyelography (RGP); cystoscopy; and ureteroscopy 3, 4.
Evaluation of Hematuria
- CT urography is a useful technique for evaluating hematuria, and it can be used alone for this task 3.
- The CT urography protocol includes an unenhanced scan, the nephrographic phase, and the excretory phase 3.
- Unenhanced scans are routinely performed to evaluate the basic parameters such as the size, shape, position, and outline of the kidneys and calculus disease 3.
- Renal parenchymal diseases, including masses, are best visualized in the nephrographic phase along with other abdominal organs 3.
- Delayed excretory phases, including the kidneys, ureters, and bladder, are useful for detecting urothelial diseases 3.
Investigation of Patients with Hematuria
- The majority of patients with microscopic hematuria undergo a complete evaluation resulting in negative findings 5.
- The outcome of patients with hematuria was analyzed in an effort to optimize the use of investigations, and it was found that age and number of RBCs/HPF in the urinalyses were the only significant factors predicting genitourinary cancer 5.
- Patients with <5 RBCs/HPF on three urinalyses are unlikely to have significant pathology and could possibly be followed up conservatively 5.
- Patients ≤40 years of age should have a noncontrast CT or ultrasound study if they present with microscopic hematuria, and a cystoscopy should be added if gross hematuria exists 5.
- In older patients, a pre- and postcontrast CT and a cystoscopy should be performed 5.