A hiatal hernia is not visible from the outside of your body. Unlike an inguinal hernia or umbilical hernia, which can create a noticeable bulge under the skin, a hiatal hernia sits deep inside the chest cavity where the stomach pushes up through the opening in the diaphragm. The only way to see one is through medical imaging or an endoscopy. What it looks like depends on which type of test is used and how much of the stomach has moved out of position.
Why You Can’t See It From the Outside
A hiatal hernia occurs at the hiatus, a small opening in the diaphragm where the esophagus passes through to connect to the stomach. When part of the stomach slides upward through that opening into the chest cavity, it creates the hernia. Because this all happens behind the ribcage and breastbone, there’s no external bulge to look for or feel. This is true even for large hiatal hernias. Most people who have one, roughly 15 to 20 percent of adults in Western countries, discover it only when a doctor orders imaging for acid reflux symptoms or finds it incidentally during a scan for something else.
What It Looks Like on a Barium Swallow X-Ray
The most classic way to visualize a hiatal hernia is a barium swallow, where you drink a chalky liquid that coats the esophagus and stomach so they show up clearly on X-ray. On these images, a sliding hiatal hernia (the most common type, accounting for about 95 percent of cases) appears as a pouch of stomach sitting above the diaphragm. Radiologists confirm the diagnosis when they can count five or more stomach folds extending more than 1 to 2 centimeters above the level of the diaphragm.
A small hernia may look subtle, just a slight bulge above the diaphragm that comes and goes as you swallow. Larger hernias are more dramatic. They can appear as a mass behind the heart, sometimes with a visible air-fluid level inside, meaning you can see a horizontal line where trapped air sits on top of liquid stomach contents. When air fills the herniated portion of the stomach above the diaphragm, the normal stomach air bubble that usually sits below the diaphragm disappears from the image.
Very large hernias can extend so far into the chest that they actually mimic an enlarged heart on a standard chest X-ray. They typically sit to the left of the spine, but the biggest ones spread beyond the heart’s silhouette. This is one reason hiatal hernias are sometimes discovered accidentally when a chest X-ray is taken for an unrelated reason.
Telling It Apart From Normal Anatomy
There’s a structure called the phrenic ampulla, a small, globe-shaped widening of the lower esophagus that sits just above the diaphragm. On imaging, it can look like a tiny hernia. The key difference is size and behavior: a phrenic ampulla is typically less than 2 centimeters long and disappears between swallows. A true hiatal hernia measures 2 centimeters or more and, in many cases, stays in place rather than sliding back down.
What It Looks Like on a CT Scan
CT scans provide a more detailed, three-dimensional picture. On a CT, a hiatal hernia shows up as stomach tissue sitting in the chest where it doesn’t belong, with a clear loss of the normal barrier the diaphragm should form. Coronal images (the front-to-back slices) are especially useful because they show the stomach being pinched at the diaphragm, creating what radiologists call the “collar sign,” a waist-like narrowing where the diaphragm squeezes the herniated tissue as it passes through.
CT scans also reveal the different types of hiatal hernia more clearly than a barium swallow. In a type 1 (sliding) hernia, the junction where the esophagus meets the stomach has migrated upward into the chest. In a type 2 (paraesophageal) hernia, that junction stays in its normal spot, but the rounded top of the stomach (the fundus) rolls up alongside the esophagus into the chest. Type 3 is a combination of both. Type 4 is the most severe: the stomach and sometimes other organs like the colon or spleen have pushed through the hiatus into the chest cavity. When oral contrast is used during the scan, the displaced stomach lights up brightly, making it easy to trace exactly how much has moved and where it sits relative to the heart and lungs.
What It Looks Like Through an Endoscope
During an upper endoscopy, a doctor threads a thin, flexible camera down through your mouth into your esophagus and stomach. From this internal view, a hiatal hernia appears as a widened opening where the esophagus passes through the diaphragm. The camera may show stomach lining folds sitting above where they should be, and the pinch point of the diaphragm may look loose or gaping rather than snug around the esophagus.
Endoscopy is also the best way to spot complications. In large hiatal hernias, the stomach folds that get pinched at the diaphragm can develop linear streaks of damage called Cameron lesions. These are shallow erosions or ulcers that run along the crests of the mucosal folds inside the hernia sac. Through the camera, they appear as thin, reddish lines sometimes covered with dark, pigmented material from old blood. Cameron lesions can cause slow, chronic bleeding that leads to iron-deficiency anemia, which is why they matter even though they’re often painless.
How Size Affects What You See
A small hiatal hernia, just a couple of centimeters, may barely register on imaging. It might only appear during a swallow and slide back into normal position moments later. Many small hernias are found incidentally and cause no symptoms at all. On endoscopy, a small hernia might just look like a slightly loose diaphragmatic opening with minimal stomach displacement.
Medium and large hernias are increasingly obvious on any type of imaging. A large paraesophageal hernia can contain most of the stomach within the chest cavity, creating a striking image where the stomach appears to sit beside or even above the heart. In the most extreme type 4 hernias, CT scans may show loops of intestine or other abdominal organs crowding into the lower chest, compressing the lungs. These large hernias almost always contain visible air-fluid levels and are hard to miss on even a routine chest X-ray.
The visual progression from small to large reflects the clinical reality: small sliding hernias are overwhelmingly common and usually harmless, while large paraesophageal hernias are rare but can cause significant problems including difficulty breathing, chest pain after eating, and in rare cases, the stomach twisting on itself (volvulus), which is a surgical emergency.