A hiatal hernia is most often diagnosed through imaging or a scope procedure, and in many cases it’s found incidentally while a doctor is investigating something else entirely, like heartburn, chest pain, or upper abdominal discomfort. The three primary diagnostic tools are a barium swallow X-ray, an upper endoscopy, and esophageal manometry. Which test you get depends on your symptoms and what your doctor needs to learn.
Many Hiatal Hernias Are Found by Accident
A large number of hiatal hernias produce no symptoms at all, so they’re discovered during tests ordered for unrelated reasons. A routine chest X-ray, for instance, can reveal a soft tissue mass behind the heart that turns out to be stomach tissue sitting above the diaphragm. Other times, a doctor investigating persistent acid reflux will confirm acid in the esophagus using a pH test, then order imaging to figure out why it’s there, and the hernia shows up.
Some people with hiatal hernias don’t have classic digestive symptoms but instead experience shortness of breath, exercise intolerance, or even abnormal findings on a heart ultrasound. SAGES guidelines emphasize that many patients referred as “asymptomatic” are actually experiencing these non-gastrointestinal symptoms caused by the hernia itself. If those symptoms can’t be explained by another condition, the hernia is likely the culprit.
Barium Swallow X-Ray
The barium swallow, also called an upper GI series, is considered the definitive method for diagnosing a hiatal hernia. You drink a chalky barium liquid that coats the lining of your esophagus and stomach, making them visible on X-ray. The radiologist then watches in real time as the barium travels through your upper digestive tract, looking for stomach tissue that has pushed up through the opening in the diaphragm.
The key measurement is the position of a specific anatomical ring (called the B ring) relative to the diaphragm. If that ring sits more than 1 to 2 centimeters above the diaphragm’s impression on the X-ray, a sliding hiatal hernia is present. Lying face-down during the test makes a sliding hernia easier to spot compared to standing upright, so your positioning matters.
The test has limitations. Small sliding hernias can be missed because they slip in and out of position. Since acid reflux from a hernia can be intermittent, a single snapshot may not catch it. And when no air is trapped inside the herniated portion of the stomach, it can be hard to distinguish from other masses behind the heart on the image.
Upper Endoscopy
An upper endoscopy (sometimes called an EGD) involves passing a thin, flexible tube with a camera down your throat to directly visualize the inside of your esophagus and stomach. You’re typically sedated for this, so you won’t feel discomfort during the procedure itself.
The doctor diagnoses a hiatal hernia by measuring the distance between two landmarks: the junction where the esophagus meets the stomach and the point where the diaphragm pinches the stomach wall. When that gap exceeds 2 centimeters, the diagnosis is confirmed. Endoscopy also lets the doctor check for inflammation, ulcers, or changes to the esophageal lining caused by chronic acid exposure, which a barium swallow can’t do.
This dual purpose makes endoscopy especially useful. It doesn’t just confirm the hernia exists; it shows what damage, if any, the hernia has caused. If you’ve had long-standing reflux symptoms, your doctor may prefer endoscopy over a barium swallow for exactly this reason.
Esophageal Manometry
Manometry measures the strength and coordination of muscle contractions in your esophagus. A thin, pressure-sensitive tube is passed through your nose and into your esophagus while you swallow sips of water. The test maps pressure along the entire length of the esophagus in real time.
In a healthy esophagus, the lower esophageal sphincter (the muscular valve at the bottom of the esophagus) and the diaphragm sit at the same level and their pressure signals overlap. When a hiatal hernia is present, those two structures separate. High-resolution manometry detects this separation with precision: when the gap between the sphincter and the diaphragm exceeds 1 centimeter, it correlates with a hernia confirmed during surgery. Once the separation exceeds 2 centimeters, the two pressure signals become completely distinct on the readout.
Manometry is particularly important if surgery is being considered. It reveals how well your esophagus is functioning, which influences the type of surgical repair your surgeon might choose. It’s less commonly used as a first-line diagnostic tool and more often ordered after a hernia has already been identified by another method.
Types of Hiatal Hernia and Why Classification Matters
There are four types of hiatal hernia, and the diagnostic workup can vary depending on which type is suspected. Type I, called a sliding hernia, is by far the most common. The junction between the esophagus and stomach slides upward through the diaphragm, often intermittently. This is the type most likely to be missed on a single barium swallow because it can reduce itself back to a normal position.
Types II, III, and IV are all forms of paraesophageal hernia, where part of the stomach (or in Type IV, other organs like the colon or spleen) pushes up alongside the esophagus through the diaphragm. These are less common but more concerning because the herniated tissue can become trapped or lose its blood supply. They tend to be larger and more visible on imaging. Researchers have proposed defining a hernia as “large” when it exceeds 7 centimeters or involves more than 50% of the stomach, though no universal standard exists.
What Determines Which Test You Get
Your symptoms guide the diagnostic path. If you’re dealing with heartburn or regurgitation, your doctor may start with a pH test to confirm acid reflux, then follow up with a barium swallow or endoscopy to look for the structural cause. If you’re having difficulty swallowing, manometry might be added to evaluate how your esophageal muscles are working.
A gastroenterologist’s clinical assessment based on your symptoms alone has a sensitivity of about 70% and a specificity of 67% for detecting reflux disease, compared to objective testing. In other words, symptom history gets it right roughly two-thirds of the time, which is why confirmatory testing is standard rather than optional.
For most people, a barium swallow or endoscopy is sufficient to confirm the diagnosis. Manometry and pH monitoring are typically reserved for cases where surgery is on the table, symptoms don’t match initial findings, or the doctor needs a more complete picture of esophageal function before deciding on treatment.