What is the recommended CT scan protocol for evaluating a hematoma in the buttocks?

Optimal CT Protocol for Buttock Hematoma Evaluation

For evaluating a hematoma in the buttocks, a contrast-enhanced CT scan with multiphase acquisition including non-contrast, arterial, and portal venous phases is the recommended protocol. 1

Rationale for Recommended Protocol

The American College of Radiology recommends CT scan as the optimal imaging modality for evaluating hematomas with specific protocol considerations:

• Multiphase acquisition is essential, including:
  • Non-contrast phase: Helps determine hematoma age and differentiate acute from chronic bleeding
  • Arterial phase: Critical for detecting active extravasation
  • Portal venous phase: Improves detection sensitivity for slower bleeding

This protocol provides several key advantages:

• High spatial resolution for precise anatomic localization
• Ability to detect active bleeding with high sensitivity (98%) and specificity (98%)
• Capacity to identify the source of hemorrhage
• Speed of acquisition, critical in potentially unstable patients

Key Imaging Parameters to Evaluate

When interpreting the CT scan for buttock hematoma, the radiologist should assess:

• Precise hematoma dimensions in three planes
• Presence/absence of active extravasation (appears as contrast blush)
• Mass effect on adjacent structures
• Development of complications (infection, abscess formation)
• Relationship to surrounding anatomical structures

Technical Considerations

1. Contrast administration: Intravenous contrast is essential for detecting active bleeding
2. Avoid oral contrast: Can mask active bleeding 1
3. CT attenuation measurements: Active hemorrhage typically measures 85-370 HU (mean 132 HU), distinguishing it from clotted blood (40-70 HU, mean 51 HU) 2

Special Considerations for Buttock Hematomas

For buttock hematomas specifically:

• Include the entire gluteal region in the scan field
• Evaluate for potential extension into the pelvis or retroperitoneum
• Assess for possible vascular injuries, particularly to gluteal vessels
• Consider relationship to pelvic fractures if trauma-related 3

Follow-up Imaging

• For stable patients: First follow-up CT scan 24-48 hours after initial scan
• Subsequent follow-up scans every 1-2 weeks if the hematoma is stable or decreasing
• Final CT scan at 3 months to document resolution 1

Pitfalls to Avoid

1. Inadequate contrast timing: May miss active extravasation
2. Omitting non-contrast phase: Makes it difficult to differentiate acute from chronic bleeding
3. Limited scan field: May miss extension of hematoma beyond the buttocks
4. Delayed scanning: May obscure hematoma visualization 4

This protocol optimizes detection of active bleeding while providing comprehensive anatomical information to guide management decisions for buttock hematomas.