What is the recommended imaging study for patients presenting with hematuria, specifically whether a CT (Computed Tomography) abdomen pelvis should be done with or without contrast?

CT Abdomen and Pelvis With IV Contrast is the Recommended Imaging Study for Hematuria

For patients presenting with hematuria, CT urography (CTU) without and with IV contrast is the recommended imaging study as it provides comprehensive evaluation of the entire urinary tract with superior detection of both renal parenchymal and urothelial lesions. 1, 2

Imaging Options Based on Patient Presentation

For Gross Hematuria:

• First-line imaging: CT urography (CTU) without and with IV contrast
  • Includes unenhanced, nephrographic, and excretory phases
  • Sensitivity of 96% and specificity of 99% for detecting urothelial malignancy 1
  • Excellent for detecting upper tract tumors (0.8% detection rate in gross hematuria) 2
  • Superior detection of small lesions compared to ultrasound or non-contrast studies 2

For Microscopic Hematuria:

• With risk factors: CTU without and with IV contrast 1

  • Risk factors include smoking history, age >35 years, occupational exposures, prior urologic disease
  • Accuracy of 99.6% for detecting upper tract lesions 1
  • Specificity and accuracy of 98.8% and 97.2% for detecting lower tract lesions 1

• Without risk factors: CT abdomen and pelvis without IV contrast may be sufficient 1

  • Particularly if there is history of recent vigorous exercise, infection, viral illness, or recent menstruation

Special Populations:

• Pregnant patients: Ultrasound of kidneys and bladder is recommended 1

  • Avoids radiation exposure to the fetus
  • Lower sensitivity but acceptable given low malignancy rate in this population

• Children:

  • Nontraumatic microscopic hematuria without proteinuria: Usually no imaging needed 1
  • Nontraumatic microscopic hematuria with proteinuria: Ultrasound of kidneys and bladder 1
  • Nontraumatic macroscopic hematuria: Ultrasound of kidneys and bladder 1

Benefits of CT Urography with Contrast

1. Comprehensive evaluation in a single examination:

   • Detects renal calculi (unenhanced phase)
   • Identifies renal parenchymal abnormalities (nephrographic phase)
   • Visualizes urothelial lesions (excretory phase) 1, 3

2. Superior diagnostic accuracy:

   • Better visibility of urothelial structures compared to MRU 1
   • Improved diagnostic confidence 1
   • High sensitivity (87%) and specificity (99%) for detecting bladder malignancy 2

Alternative Imaging Options

• MR urography (MRU) without and with IV contrast:

  • Alternative for patients with renal insufficiency or contrast allergy 2
  • Comparable accuracy to CT for renal masses 1
  • Limitations: decreased spatial resolution, difficulty detecting small calculi and urothelial lesions 1

• Ultrasound:

  • Limited sensitivity (35.3-50.7%) compared to CT 2
  • Not recommended as first-line for non-pregnant adults with hematuria 1

Common Pitfalls and Considerations

1. Radiation exposure:

   • Important consideration, especially in younger patients 2
   • For young adults (≤40 years) without predisposing conditions, unenhanced CT alone may be sufficient 4
   • 94.8% of clinically significant findings in young adults were evident on unenhanced images 4

2. Contrast administration:

   • Requires adequate renal function 2
   • Assess for contrast allergies before administration

3. Repeat imaging:

   • Repeat CTU within 3 years is unlikely to show urinary tract malignancy if initial study was negative 5
   • Follow published guidelines for repeat imaging

4. Disease prevalence:

   • In patients with hematuria undergoing CTU, clinically significant findings are detected in approximately 22% of cases 6, 4
   • Higher yield in visible (gross) hematuria (48%) versus non-visible (microscopic) hematuria (29%) 6

By following these evidence-based recommendations, clinicians can optimize the diagnostic evaluation of patients with hematuria while balancing the benefits of comprehensive assessment against considerations of radiation exposure and contrast administration.