Detection of Abdominal Wall Fluid Collections on CT Without Contrast

Imaging Characteristics of Fluid Collections on Non-Contrast CT

• Non-contrast CT can identify fluid collections in the abdominal wall based on their characteristic appearance as hypodense areas with fluid attenuation (typically 0-20 Hounsfield Units) 1

Limitations of Non-Contrast CT for Fluid Collections

• Without IV contrast, it is more difficult to determine if there is active bleeding into the collection 1
• The sensitivity for detecting small fluid collections may be lower without contrast enhancement 2, 3

Clinical Applications

• Non-contrast CT is particularly useful in patients with contraindications to IV contrast (renal insufficiency, severe contrast allergy) 4

Enhanced Diagnostic Accuracy with Contrast

• CT with IV contrast provides superior characterization of fluid collections by better delineating the relationship to adjacent structures 5, 6
• CT with IV contrast improves detection of active bleeding or vascular complications 1

Diagnostic Algorithm for Abdominal Wall Fluid Collections

• For initial detection in patients who cannot receive contrast, non-contrast CT can identify the presence, location, and approximate size of fluid collections 4
• For better characterization when clinically feasible, CT with IV contrast is preferred for detailed assessment 5, 6
• Consider CT with both IV and oral/rectal contrast when evaluating for fistula or leak 6, 7

Pitfalls and Considerations

• Small fluid collections may be missed on non-contrast CT, especially if adjacent to structures of similar density 3