Can an umbilical hernia be identified on a Computed Tomography (CT) scan without contrast?

Identification of Umbilical Hernia on CT Without Contrast

Yes, umbilical hernias can be identified on CT scans without contrast, though CT with contrast provides better visualization of potential complications.

Diagnostic Capability of Non-Contrast CT for Umbilical Hernias

Non-contrast CT can effectively detect umbilical hernias through visualization of:

• Defect in the abdominal wall at the umbilicus
• Protrusion of peritoneal fat or abdominal contents through the defect
• Anatomical relationship to surrounding structures

Evidence Supporting Non-Contrast CT Detection

Recent research demonstrates that CT is highly effective in identifying umbilical hernias, with a 2024 study showing that 62.4% of patients had umbilical hernias identifiable on CT 1. Importantly, this study revealed that approximately 64.8% of these hernias were not reported in radiological interpretations, indicating significant underdiagnosis 1.

Another 2024 study found a 67.6% prevalence of umbilical hernias detectable on CT scans, with 63.6% unreported by radiologists 2. This suggests that umbilical hernias are readily visible on CT but frequently overlooked in clinical practice.

Advantages and Limitations of Non-Contrast CT

Advantages:

• Readily available in most healthcare settings
• Can identify the hernia defect size and contents
• Can detect complications such as incarceration
• Useful in obese patients where physical examination may be limited

Limitations:

• Less sensitive than contrast-enhanced CT for detecting complications
• May miss subtle inflammatory changes or vascular compromise
• Smaller hernias (average 7.7 × 6.0 mm) are more frequently missed in radiological reports 1

Clinical Implications

Non-contrast CT can be particularly valuable in cases where umbilical hernias are not clinically apparent. A 2022 case report described an "invisible incarcerated umbilical hernia" in an obese woman that was only diagnosed through CT imaging 3. The authors emphasized that "umbilical hernia should be considered in obese women even without bulging in the umbilicus" and that "abdominal CT scan with oral water-soluble contrast is preferred as diagnostic tool" 3.

Contrast vs. Non-Contrast CT

While non-contrast CT can identify umbilical hernias, contrast-enhanced studies provide additional benefits:

1. Better visualization of vascular structures
2. Improved detection of complications (strangulation, ischemia)
3. Enhanced ability to identify alternative diagnoses

The ACR Appropriateness Criteria for abdominal imaging suggests that CT with IV contrast generally provides superior diagnostic information about extra-aortic pathology compared to non-contrast studies 4.

Recommendations for Clinical Practice

1. For routine identification of umbilical hernias:

   • Non-contrast CT is adequate for detection of the hernia defect and contents

2. For suspected complications:

   • CT with IV contrast is preferred to assess for strangulation, ischemia, or other complications

3. For obese patients with suspected small bowel obstruction:

   • Consider CT evaluation even without visible umbilical bulging on examination 3

4. When reviewing CT scans:

   • Specifically examine the umbilical region, as hernias are frequently underreported 2, 1

Conclusion

Non-contrast CT can effectively identify umbilical hernias, though they are frequently underreported in radiological interpretations. For optimal assessment of potential complications, contrast-enhanced CT provides superior visualization of vascular structures and inflammatory changes.