From the Guidelines
Hematuria, as shown on a Computed Tomography (CT) scan, can be caused by various factors, including urinary tract malignancy, urolithiasis, infection, and benign prostatic hypertrophy, with the most common benign cause being renal parenchymal disease. The evaluation of hematuria should start with a thorough history, physical examination, urinalysis, and serologic testing prior to any initial imaging 1.
Causes of Hematuria
The causes of hematuria can arise from anywhere along the urinary tract and are generally divided into nephrogenic and urogenic causes. Common benign urogenic causes of hematuria include urolithiasis, infection, and benign prostatic hypertrophy 1. Malignant causes can occur anywhere in the urinary tract and are the main entity that must be excluded during the imaging evaluation of hematuria.
Imaging Evaluation
For patients with gross hematuria, a full urologic workup is recommended, including a CT urogram, which is superior to ultrasound for detecting small renal masses and urothelial lesions 1. However, the use of CT urography also carries potential harms, including nephropathy from intravenous contrast and the risk of life-threatening hypersensitivity reactions to contrast, as well as the potential longer-term harm of ionizing radiation exposure 1.
Recommendations
The preferred protocol for evaluating hematuria is a CT urogram, which includes non-contrast, nephrographic, and excretory phases to comprehensively assess the kidneys, ureters, and bladder. Patients should be well-hydrated before the scan and should empty their bladder immediately before imaging to optimize visualization of the lower urinary tract. For patients with contraindications to contrast, a non-contrast CT can still identify urolithiasis but has limited sensitivity for detecting malignancies.
Considerations
The examination should be performed before cystoscopy to guide the endoscopic evaluation. Patients without risk factors and with an identified benign cause of microhematuria are unlikely to gain any benefit from a complete imaging workup of microhematuria 1. The use of anticoagulant therapy does not alter the urologic evaluation of microhematuria 1.
Key Points
- Hematuria can be caused by various factors, including urinary tract malignancy, urolithiasis, infection, and benign prostatic hypertrophy.
- The evaluation of hematuria should start with a thorough history, physical examination, urinalysis, and serologic testing prior to any initial imaging.
- A CT urogram is the preferred protocol for evaluating hematuria, particularly when there is concern for urinary tract malignancy or urolithiasis.
- Patients should be well-hydrated before the scan and should empty their bladder immediately before imaging to optimize visualization of the lower urinary tract.
From the Research
Causes of Hematuria
The causes of hematuria (blood in urine) can be varied and may signify serious diseases. Some of the possible causes include:
- Bladder cancer
- Upper urinary tract urothelial cell carcinoma (UUT-UCC)
- Renal cell cancer
- Urinary tract stones
- Infection or anomaly in the urinary tract 2, 3, 4
Diagnostic Techniques
Computed Tomography (CT) urography is a diagnostic technique used to investigate hematuria. It involves a CT examination of the kidneys, ureters, and bladder with at least one series of images acquired during the excretory phase after intravenous contrast administration. CT urography has high diagnostic accuracy for urothelial cell carcinoma (UCC) and is recommended as the initial imaging test for hematuria in patients at high-risk for UCC 2, 5, 4.
Comparison with Other Imaging Techniques
CT urography is compared with other imaging techniques such as ultrasonography, intravenous urography, or retrograde ureteropyelography. While ultrasonography can be useful in detecting renal cancer, it is poor at identifying upper tract urothelial cancer and renal calculi. CT urography is preferred over excretory urography in most cases due to its higher sensitivity and accuracy 3, 5, 6.
Patient Evaluation
Patients with hematuria are evaluated based on the presence of visible or non-visible hematuria. Lesions are found more frequently in patients with visible hematuria than in patients with non-visible hematuria. No malignant tumor or complex cyst is found in the kidneys or the ureters in patients with non-visible hematuria 3. The incidence of urinary tract cancer is higher in patients with macroscopic hematuria than in those with microscopic hematuria 6.