Imaging for Ventral Hernia Diagnosis
Contrast-enhanced CT scan of the abdomen and pelvis with IV contrast is the imaging modality of choice for diagnosing ventral hernias, providing superior diagnostic accuracy compared to physical examination alone and enabling identification of hernia location, contents, size, and potential complications. 1, 2
Primary Imaging Recommendation
CT abdomen and pelvis with IV contrast is the gold standard for ventral hernia diagnosis, offering the ability to detect hernia defects, characterize hernial contents, measure defect size, and identify complications such as bowel obstruction, ischemia, or strangulation 1, 2
The scan should include multiplanar reconstructions to increase accuracy in locating transition zones and hernia defects 1
IV contrast is essential to assess bowel wall enhancement patterns that indicate ischemia and to evaluate vascular perfusion for detecting complications 1
Contrast Protocol Considerations
Both IV and oral contrast are fundamental when evaluating post-surgical or complex hernias, as they help identify anatomical landmarks and hernial contents 3, 1
Avoid oral contrast in cases of suspected high-grade bowel obstruction, as it delays diagnosis and increases patient discomfort without adding diagnostic value 1
If IV or oral contrast is contraindicated (allergy, acute kidney failure), proceed directly to diagnostic laparoscopy due to the low sensitivity of non-contrast studies 3
Key CT Findings to Identify
Discontinuity of the abdominal wall at the hernia defect site 2
"Collar sign" indicating herniated contents passing through a fascial defect 1, 2
Signs of complications: bowel wall thickening, pneumatosis, lack of contrast enhancement (indicating ischemia), or free fluid 2
Clustered or crowded dilated bowel loops suggesting obstruction or internal hernia 1
Clinical Context and Limitations
Clinical examination combined with CT provides the most accurate diagnostic approach, as physical examination alone has limited sensitivity, particularly in obese patients or those with prior abdominal surgery 2
CT has moderate interobserver reliability among radiologists for ventral hernia diagnosis (43% agreement, κ = 0.50), with agreement highest in clinically obvious cases and lowest in indeterminate presentations 4
CT sensitivity for ventral hernia is only 37% but specificity is 83%, meaning negative CT scans can miss hernias, particularly small or intermittent defects 4
Alternative Imaging Modalities
Point-of-care ultrasound (POCUS) can be useful for initial evaluation of suspected hernias, particularly in resource-limited settings or when CT is not immediately available 1
MRI may be considered in pregnant patients to avoid radiation exposure, though CT remains superior for comprehensive evaluation in non-pregnant patients 3
Critical Pitfalls to Avoid
Never rely solely on a negative CT to exclude a ventral hernia, especially in patients with high clinical suspicion—maintain a low threshold for surgical exploration if symptoms persist despite negative imaging 1, 4
Do not order non-contrast CT when evaluating for potential complications, as it cannot assess vascular perfusion or bowel viability 1
Ensure the scan includes the pelvis, not just the abdomen, to capture the full extent of potential hernias and avoid missing lower abdominal wall defects 1
Clinical examination remains notoriously unreliable in obese patients or those with significant prior surgery (absent guarding, flaccid abdomen), making imaging even more critical in these populations 1