CT Urography Protocol for Gross Hematuria
For gross hematuria in adults, perform a complete CT urography (CTU) protocol consisting of unenhanced images followed by IV contrast-enhanced nephrographic and excretory phases acquired at least 5 minutes after contrast injection. 1
Protocol Components
The ACR Appropriateness Criteria explicitly define CTU as requiring:
- Unenhanced (non-contrast) phase: Essential for detecting renal calculi and establishing baseline attenuation values 1, 2
- Nephrographic phase: Obtained after IV contrast administration for optimal visualization of renal parenchymal masses and other abdominal organs 1, 3
- Excretory phase: Delayed images acquired at least 5 minutes post-contrast to evaluate the urothelium of the upper and lower urinary tracts 1
Technical Parameters
CTU must include thin-slice acquisition with reconstruction methods using maximum intensity projection (MIP) or 3-D volume rendering 1. This distinguishes true CTU from a standard "CT abdomen/pelvis with contrast," which lacks the precontrast and excretory phases specifically tailored for urinary tract evaluation 1.
Alternative Split-Bolus Technique
Some centers use a split-bolus approach: an initial loading dose of IV contrast followed by a combined nephrographic-excretory phase after a second contrast dose. Some protocols also include an arterial phase 1.
Clinical Rationale
Gross hematuria carries a 30-40% association with malignancy, mandating complete urologic workup 1. CTU is recommended because it can detect both upper tract urothelial carcinomas and bladder malignancies in a single comprehensive examination 1, 3.
Diagnostic Performance
The evidence shows variable but generally strong performance for CTU in gross hematuria:
- One study demonstrated CTU sensitivity and specificity for bladder malignancy of 87% and 99% respectively, comparable to cystoscopy 1
- The DETECT 1 study recommends CTU for gross hematuria given the 0.8% upper tract tumor rate 1
- Recent data suggests all upper tract urothelial carcinomas were visible on the nephrographic phase 4
Important Caveats
Do not substitute a standard CT abdomen/pelvis for CTU. The ACR explicitly distinguishes between these protocols—standard CT lacks both the precontrast phase (critical for stone detection) and the excretory phase (essential for urothelial evaluation) 1.
Ultrasound is inadequate for gross hematuria. US demonstrated only 35.3% sensitivity for bladder pathology in one study and 50.7% in a multicenter trial, far inferior to CT 1. While contrast-enhanced ultrasound (CEUS) improves accuracy to 88%, it remains a second-line modality 1.
Special Populations
For pregnant patients with gross hematuria, the approach differs: ultrasound kidneys and bladder is appropriate initially given radiation concerns, with full workup deferred until after delivery once gynecologic bleeding and benign causes are excluded 1.
MR urography can be considered as an alternative to CTU for gross hematuria 1, though direct comparative data is limited. One study showed MRI without contrast had 98.5% sensitivity for determining gross hematuria causes 1. However, MRI has decreased spatial resolution compared to CT and may miss small calculi and urothelial lesions 1.