CT Scan for Hiatal Hernia Evaluation
Fluoroscopic studies (biphasic esophagram or upper GI series) are the most appropriate first-line imaging for hiatal hernia evaluation, not CT scan. 1, 2
Preferred Imaging Modality
The American College of Radiology recommends fluoroscopic studies—specifically biphasic esophagram, single-contrast esophagram, or upper GI series—as the most appropriate initial imaging for suspected hiatal hernia. 1, 2
The biphasic esophagram achieves 88% sensitivity by combining double-contrast views (optimizing detection of inflammatory conditions) with single-contrast views (optimizing detection of hiatal hernias and esophageal rings/strictures). 2
These fluoroscopic studies provide both anatomic and functional information on esophageal length, esophageal stricture presence, and gastroesophageal reflux that CT cannot provide. 1
For large hiatal hernias, an upper GI series evaluation is specifically recommended for complete assessment of the stomach. 1
When CT Is Appropriate
If CT is performed for hiatal hernia evaluation, use CT abdomen with IV contrast rather than non-contrast CT. 1, 3
CT Protocol Specifications:
CT with IV contrast provides superior visualization of the relationship between the hernia and surrounding vascular structures, and can detect complications such as ischemia or strangulation. 1, 3
Non-contrast CT offers limited assessment of vascular structures and may not adequately visualize potential complications. 1
CT findings of ischemia include absence of gastric wall contrast enhancement, intestinal wall thickening with target enhancement, and lack of enhancement after iodinated contrast injection. 4, 3
CT's Role in Hiatal Hernia:
CT scan is the gold standard for diagnosing complicated diaphragmatic hernias (including complicated hiatal hernias), with sensitivity of 14-82% and specificity of 87%. 4, 2
CT is superior for determining presence, location, and size of diaphragmatic defects when chest X-ray findings are inconclusive but clinical suspicion remains high. 4, 2
CT can identify key findings including diaphragmatic discontinuity, "collar sign" (constriction of herniating organ at rupture level), "dependent viscera" sign, and intrathoracic herniation of abdominal contents. 4, 3
Critical Pitfalls to Avoid
Do not order CT as first-line imaging for hiatal hernia when fluoroscopic studies are more appropriate and informative. 1
Do not use non-contrast CT when vascular assessment is needed, particularly when evaluating the relationship between the hernia and cardiac structures. 1
Be aware that small sliding hiatal hernias can be artifactually induced by colonic distention during CT colonography or CT with water enema—these physiologic hernias may not be clinically significant and should not be reported in asymptomatic patients without GERD symptoms. 5
Incidental hiatal hernias on CT have a 10.6% incidence in trauma imaging, but only 1.2% receive appropriate follow-up referral, representing a significant gap in care. 6
Special Populations
In pregnant patients with suspected non-traumatic diaphragmatic hernia, use ultrasonography as the first diagnostic study, followed by MRI if necessary, to avoid radiation exposure. 1, 3
Real-time MRI at 3.0 Tesla can visualize hiatal hernias during Valsalva maneuver that are occult on static imaging or endoscopy, with comparable diagnostic accuracy to endoscopy (74% vs 80% sensitivity). 7