CT Urogram Recommendations
CT urography is strongly indicated for patients with high-risk hematuria, suspected upper tract urothelial carcinoma, recurrent complicated UTIs, and evaluation of complex urinary tract abnormalities when detailed imaging of the entire urinary system is required. 1
Primary Indications for CT Urography
CT urography has become the gold standard imaging modality for several urinary tract conditions, replacing traditional intravenous urography (IVU) in most clinical scenarios:
Hematuria evaluation, particularly in high-risk patients:
- Age >35 years with gross or persistent microscopic hematuria
- History of smoking
- Occupational exposures
- Irritative voiding symptoms
- Prior pelvic radiation therapy or cyclophosphamide/ifosfamide chemotherapy
- Family history of urothelial cancer or Lynch Syndrome 1
Suspected urinary tract malignancies:
Urinary tract trauma assessment:
Urolithiasis detection, including CT-radiolucent stones that might be missed on regular CT 1, 4
Recurrent complicated UTIs to identify underlying anatomical abnormalities 1
Congenital anomalies of the kidneys and ureters 1
Technical Considerations
A complete CT urogram typically includes:
- Unenhanced phase - excellent for detecting calcifications and stones
- Nephrographic phase - optimal for renal parenchymal assessment
- Excretory phase (5-minute delay) - critical for evaluating the collecting system, ureters, and bladder 1, 4
The excretory phase is particularly valuable as it allows visualization of filling defects, urothelial lesions, and urinary extravasation that might be missed without this delayed imaging 4.
Special Clinical Scenarios
Urinary Tract Trauma
In trauma patients, CT with intravenous contrast is considered the gold standard. The addition of a 5-minute delayed phase (excretory phase) permits the identification of urinary extravasation 3. This delayed phase should be added selectively when urogenital injuries are suspected.
Urinary Tract Complications
For patients with deep renal lacerations (AAST Grade IV-V) or clinical signs of complications (fever, worsening flank pain, ongoing blood loss, abdominal distention), follow-up CT imaging is recommended after 48 hours 3. However, routine follow-up CT imaging is not advised for uncomplicated AAST Grade I-III injuries.
Suspected Ureteral Injuries
IV contrast-enhanced abdominal/pelvic CT with delayed imaging (urogram) is recommended for stable trauma patients with suspected ureteral injuries 3.
Diagnostic Performance
CT urography demonstrates excellent diagnostic capabilities:
- Sensitivity of 81-84% and specificity of 87.5% for urinary tract abnormalities 1
- Superior to ultrasound for detecting upper tract urothelial carcinoma 1
- Correctly diagnoses 97.5% of urolithiasis cases 5
Alternative Imaging Options
When CT urography is contraindicated, consider:
MR urography - for patients with:
- Contraindications to iodinated contrast
- Pregnancy
- Renal insufficiency 1
Ultrasound with retrograde pyelography - when both CT and MR are contraindicated, though with lower sensitivity (45%) compared to CT 1
Non-contrast CT with retrograde pyelography - an alternative when contrast-enhanced CT is contraindicated 1
Important Caveats
- Consider radiation exposure in younger patients or those requiring repeated imaging
- Ensure adequate renal function before administering contrast
- CT urography requires approximately 30-45 minutes to complete
- Patients should inform their doctor of any allergies to contrast materials 1
- While more expensive than ultrasound, CT urography provides more comprehensive information in a single examination 1, 6
CT urography has revolutionized urinary tract imaging by providing detailed anatomic depiction of the entire urinary system in one comprehensive examination, making it the preferred modality for evaluating patients with urinary tract issues when detailed assessment is required.