What is the best imaging scan for hematuria (blood in urine)?

From the Guidelines

The best imaging scan for hematuria is typically a CT urogram (CTU), which combines a non-contrast CT scan with contrast-enhanced images of the urinary tract. This recommendation is based on the highest quality and most recent evidence, which suggests that CTU has been shown to be the imaging study of choice for the evaluation of microhematuria because it can evaluate both nephrogenic and urogenic causes of hematuria 1. The CTU has been proven to be a very sensitive and specific method for the detection of urothelial malignancy, with a pooled sensitivity of 96% and pooled specificity of 99% 1.

For initial evaluation of hematuria, this three-phase study provides a comprehensive assessment of the kidneys, ureters, and bladder. The CTU can detect urinary stones, renal masses, urothelial tumors, and other potential causes of bleeding. Some key points to consider when choosing an imaging scan for hematuria include:

• The patient's clinical presentation and risk factors for bladder cancer or other urological malignancies
• The presence of any contraindications to CT or contrast, such as pregnancy or renal insufficiency
• The need for alternative imaging modalities, such as ultrasound or MR urography, in certain patient populations

Alternatives to CTU include ultrasound combined with plain radiography (KUB) for patients with contraindications to CT or contrast, such as pregnancy or renal insufficiency. MR urography may be used for patients who cannot receive iodinated contrast 1. Cystoscopy often complements imaging studies, particularly for patients over 35 or those with risk factors for bladder cancer. The choice of imaging should be tailored to the patient's clinical presentation, with CTU offering the highest sensitivity for detecting urological malignancies and calculi, which are important causes of hematuria requiring prompt diagnosis and treatment.

From the Research

Imaging Options for Hematuria

• CT urography is a recommended initial imaging test for hematuria in patients at high-risk for urothelial cell carcinoma (UCC) 2
• Multidetector computed tomography urography is preferred over excretory urography in most cases due to its higher sensitivity for detection of small tumors and calculi 3, 4
• Ultrasound alone is insufficient for imaging of hematuria, as it can be difficult to differentiate renal transitional cell carcinoma from other causes of filling defects 3
• Low-dose CT offers greater sensitivities for the detection of urinary tract calculi than radiography 3

Guidelines for Imaging Hematuria

• The American Urological Association criteria for radiologic evaluation of hematuria include more than 3 RBCs per high-power field in the absence of urinary tract infection 5
• The American College of Radiology's appropriateness criteria recommend computed tomography urography as the primary imaging modality for evaluating hematuria, with ultrasound and magnetic resonance imaging as alternative options in specific cases 4
• A four-phase MSCT protocol is an accurate tool to diagnose the cause of unclear hematuria in the majority of cases, but examination protocols can be tailored to reduce radiation exposure in certain patient populations 6

Diagnostic Yield of CT Urography

• The yield of CT urography for upper urinary tract malignancy is low, with no upper tract urothelial neoplasms identified in one study of 419 patients 5
• CT urography can detect other causes of hematuria, such as renal cell cancer, stones, and bladder cancer, but may not be necessary for patients who do not meet the criteria for radiologic evaluation 2, 5