A hiatal hernia is most often diagnosed through an upper GI X-ray (barium swallow), an upper endoscopy, or both. Many people learn they have one incidentally, during testing for heartburn, chest pain, or difficulty swallowing. There’s no single blood test or physical exam finding that confirms a hiatal hernia, so imaging or a scope procedure is necessary to see the stomach pushing through the diaphragm.
Barium Swallow (Upper GI Series)
A barium swallow is one of the most straightforward ways to identify a hiatal hernia. You drink a chalky liquid that coats the lining of your esophagus and stomach, making them visible on X-ray. As the barium moves through your digestive tract, a radiologist watches in real time and captures images that show whether part of your stomach has slid upward through the opening in your diaphragm.
Specific details on the X-ray confirm the diagnosis. If a ring of tissue at the junction between your esophagus and stomach sits more than 1 to 2 centimeters above the diaphragm impression, a sliding hiatal hernia is present. Lying face down during the exam actually makes a sliding hernia easier to spot than standing upright, so you may be positioned on your stomach for part of the test. The barium swallow can also reveal signs of acid reflux or inflammation in the esophagus, which frequently accompanies a hernia.
Upper Endoscopy
An upper endoscopy gives your doctor a direct, close-up view of the esophagus, the junction where it meets the stomach, and the stomach itself. A thin, flexible tube with a camera on the end is passed down your throat while you’re sedated. The doctor can see inflammation, ulcers, or structural changes caused by the hernia.
To evaluate the hernia, the scope is advanced into the stomach and then turned back on itself (a maneuver called retroflexion) so the camera looks upward at the junction from below. The doctor inflates the stomach with air for about 30 to 45 seconds until the folds of the stomach lining flatten out, giving a clear view. They may also gently pull the scope along the inner wall to see whether the stomach slides upward through the diaphragm opening.
Doctors grade what they see using a system called the Hill classification, which runs from Grade I to Grade IV. Grades I and II are considered normal: the tissue flap where the esophagus meets the stomach grips snugly around the scope, and there’s a healthy length of esophagus sitting below the diaphragm. Grade III shows a visible hernia with the stomach-esophagus junction displaced upward and the diaphragm opening gaping on the camera view. Grade IV is similar but with a larger, wider opening and more of the stomach herniated into the chest. Grades III and IV correlate with more significant reflux problems.
Pressure Testing (Manometry)
Esophageal manometry measures the strength and coordination of muscle contractions in your esophagus. A thin catheter with pressure sensors is passed through your nose and into your esophagus, and you’re asked to take sips of water while the sensors record how your muscles squeeze. This test doesn’t replace imaging, but it provides information that imaging alone can’t.
In a healthy anatomy, two structures create a high-pressure zone at the bottom of your esophagus: the muscular valve at the end of the esophagus and the ring of diaphragm muscle that surrounds it. Normally these two sit right on top of each other. When a hiatal hernia is present, the stomach pulls the esophageal valve upward and away from the diaphragm, creating a measurable gap between the two pressure signals. A separation greater than 1 centimeter on manometry correlates with a hernia confirmed during surgery. When the gap exceeds 2 centimeters, the two pressure signatures become completely distinct on the recording.
Manometry is particularly useful before surgery, because it tells the surgical team how well your esophagus is functioning and helps them plan the best repair approach.
CT Scans and Incidental Findings
Many hiatal hernias are discovered on CT scans ordered for something else entirely, like chest pain, a lung issue, or abdominal symptoms. A CT can show part of the stomach sitting above the diaphragm, sometimes with a visible air-fluid level behind the heart. While CT isn’t the primary tool for diagnosing a hiatal hernia, it’s often the first clue, and it’s especially valuable in emergency situations where a large hernia may be causing acute symptoms like severe pain or obstruction.
Sliding vs. Paraesophageal Hernias
Part of the diagnostic process involves determining which type of hernia you have, because the type affects whether you need treatment. A sliding hernia (Type I) is the most common. It happens when the junction between the esophagus and stomach slides upward through the diaphragm, often dragging a portion of the stomach along with it. These hernias can move up and down, which is why they sometimes appear on one test but not another.
Paraesophageal hernias (Types II through IV) are less common but more concerning. In these, a portion of the stomach pushes up through the diaphragm opening and sits next to the esophagus rather than sliding along with it. In the most advanced form (Type IV), other organs can herniate into the chest as well. Barium swallow and CT imaging are both effective at distinguishing between these types, and the distinction matters because paraesophageal hernias carry a higher risk of complications like the stomach twisting or losing its blood supply.
Acid Reflux Monitoring
If your doctor suspects that a hiatal hernia is driving reflux symptoms, you may undergo ambulatory pH monitoring. A small probe is placed in your esophagus (either clipped to the lining or threaded through your nose) and left in place for 24 to 48 hours while you go about your normal routine. The probe measures how often acid washes up from the stomach and whether those episodes line up with your symptoms.
This test doesn’t diagnose the hernia itself, but it documents the functional damage the hernia is causing. The results help determine whether antireflux surgery would likely improve your symptoms. A strong correlation between your symptom episodes and measured acid exposure is one of the best predictors of a good surgical outcome.
Why Chest Pain Requires a Broader Workup
Hiatal hernias can cause chest pain that feels identical to a heart attack. The pain from acid reflux associated with a hernia can occur without any heartburn or regurgitation, making it genuinely difficult to distinguish from cardiac chest pain based on symptoms alone. When you show up with chest pain, doctors will typically rule out heart problems and aortic emergencies first before pursuing a hernia diagnosis. This isn’t a sign that your concerns are being dismissed. It’s a necessary step because the chest pain overlap between these conditions is real and well documented.
What Size Matters for Diagnosis
There’s no universal size threshold that separates a “real” hernia from an insignificant one. Small sliding hernias are extremely common and often cause no symptoms at all. Researchers have proposed defining a large hiatal hernia as one bigger than 7 centimeters (about 2.8 inches) or one involving more than half the stomach, but this definition isn’t standardized across all medical guidelines. In practice, what matters more than size alone is whether the hernia is causing symptoms, damaging your esophagus, or posing a risk of complications like obstruction or strangulation.