What is the preferred imaging protocol for a computed tomography (CT) abdomen with or without contrast in patients presenting with hematuria?

From the Guidelines

For patients presenting with hematuria, the preferred CT imaging protocol is a CT urogram (CTU) without and with IV contrast, as it is usually appropriate for the initial imaging of both microhematuria in patients with risk factors and gross hematuria. This recommendation is based on the most recent and highest quality study available, which suggests that CTU without and with IV contrast is the most appropriate imaging modality for detecting urinary tract calculi, renal masses, urothelial tumors, and other potential causes of hematuria 1.

The CTU protocol should include both non-contrast and contrast-enhanced phases to evaluate the urinary tract and detect potential causes of hematuria. The non-contrast phase is essential for detecting urinary tract calculi, while the contrast-enhanced phase helps to evaluate renal parenchymal lesions and assess the collecting systems, ureters, and bladder. According to a recent study, CTU demonstrated a 91% diagnostic accuracy in detecting urothelial cancers, making it a valuable tool in the diagnosis and staging of urothelial malignancies 1.

Some key points to consider when performing a CTU include:

• Administering intravenous contrast at a rate of 3-4 mL/second with a total volume of 100-150 mL of iodinated contrast material
• Ensuring patients are well-hydrated and have renal function assessed with serum creatinine to minimize contrast-induced nephropathy risk
• Having patients empty their bladder immediately before the excretory phase images to optimize visualization of bladder lesions
• Using a multiphasic approach, including non-contrast, nephrographic, and excretory phases, to detect potential causes of hematuria

It's worth noting that the American College of Radiology (ACR) Appropriateness Criteria recommend CTU without and with IV contrast as the initial imaging modality for patients with gross hematuria and microhematuria with risk factors 1. Additionally, a recent retrospective analysis demonstrated the feasibility of using preoperative CTU features to predict the risk stratification of non-muscle-invasive bladder cancer, highlighting the potential of CTU in patient evaluation 1.

From the Research

Imaging Protocols for CT Abdomen with or without Contrast in Patients with Hematuria

• The preferred imaging protocol for a computed tomography (CT) abdomen with or without contrast in patients presenting with hematuria involves a comprehensive contrast material-enhanced multi-detector row CT protocol that combines unenhanced, nephrographic-phase, and excretory-phase imaging 2.
• CT urography is a rapidly evolving technique that is defined as CT examination of the kidneys, ureters, and bladder with at least one series of images acquired during the excretory phase after intravenous contrast administration, and is recommended as the initial imaging test for hematuria in patients at high-risk for urothelial cell carcinoma (UCC) 3.
• The use of CT urography with a low dose of contrast medium and radiation is a useful diagnostic imaging test for investigating patients with hematuria, with a disease prevalence of 42% in patients with visible hematuria and 29% in patients with non-visible hematuria 4.

Diagnostic Yield of CT Urography

• The diagnostic yield of CT urography in young adults with hematuria is 22.1%, with the most common clinically significant findings being renal or ureteral calculi (75.3%) and malignancies (4 cases) 5.
• In patients without additional predisposing medical conditions, an unenhanced CT alone may be sufficient, thereby reducing radiation dose in this radiosensitive population 5.

Role of Imaging Modalities

• Various imaging modalities, including plain radiography, intravenous urography or excretory urography, retrograde pyelography, ultrasonography, and multidetector computed tomography (MDCT) can be used to evaluate patients with hematuria, with MDCT urography being a valuable tool in imaging of patients with hematuria 6.
• The optimal protocol design, accuracy of the technique in imaging of the urothelium, and the significant issue of radiation dose associated with MDCT urography are important considerations in the evaluation of patients with hematuria 6.