A hiatal hernia is diagnosed when imaging or a scope shows that part of your stomach has pushed up through the opening in your diaphragm (called the hiatus) into your chest cavity. The key measurement is a 2 cm threshold: if the junction between your esophagus and stomach sits more than 2 cm above the diaphragm, that confirms a hernia. Most hiatal hernias are found during tests ordered for other reasons, like persistent heartburn or difficulty swallowing, rather than through a dedicated hernia workup.
Why Symptoms Alone Aren’t Enough
Many people with a hiatal hernia have no symptoms at all. Others experience heartburn, chest pressure, or trouble swallowing that overlaps heavily with ordinary acid reflux. A gastroenterologist’s clinical history, even a thorough one, has only about 70% sensitivity and 67% specificity for identifying reflux-related problems. That means roughly 3 in 10 cases get missed or misidentified based on symptoms alone. Because of this overlap, confirming a hiatal hernia requires at least one objective test.
It’s also worth knowing that some hiatal hernias cause symptoms you might not connect to your stomach. Shortness of breath, exercise intolerance, and even abnormal heart findings on an echocardiogram can all be caused by a large hernia pushing into the chest. Patients referred for an “asymptomatic” hernia are sometimes experiencing these non-digestive symptoms without realizing the connection.
Barium Swallow: The Classic Imaging Test
A barium swallow is one of the oldest and most straightforward ways to spot a hiatal hernia. You drink a chalky liquid containing barium, which coats your esophagus and stomach, then a radiologist takes X-ray images as the barium travels down. The whole process takes 30 to 60 minutes.
On these images, a sliding hiatal hernia (the most common type) shows up when the junction between the esophagus and stomach sits more than 2 cm above the diaphragm. Radiologists look for a landmark called the “B ring,” which marks that junction. Even when the B ring isn’t clearly visible, the hernia can still be confirmed by spotting stomach folds (called rugae) in the portion that has pushed upward into the chest.
Positioning matters. Having you lie face-down in a slightly angled position significantly increases the chance of catching smaller hernias that might not show up when you’re standing upright. This is why you’ll likely be asked to shift positions during the exam.
A barium swallow can also reveal the less common but more serious types. In a paraesophageal hernia, the esophagus-stomach junction stays in its normal spot, but a portion of the stomach rolls up beside the esophagus into the chest. A “mixed” or compound hernia combines both features: the junction moves upward and a large section of the stomach herniates and often rotates abnormally.
Preparation
You’ll typically fast from midnight the night before. Your provider may ask you to avoid smoking, chewing gum, or sucking on hard candy beforehand, since anything that coats your throat can interfere with the images. Let your provider know about all medications you take, as some may need to be paused.
Upper Endoscopy: A Direct Look Inside
Upper endoscopy (also called EGD) gives your gastroenterologist a live, inside view. A thin, flexible tube with a camera is guided through your mouth into your esophagus and stomach. This test does double duty: it can confirm the hernia and check for complications like inflammation, ulcers, or changes to the esophageal lining from chronic acid exposure.
During endoscopy, the hernia is identified when the junction between your esophagus and stomach is displaced more than 2 cm above the impression of the diaphragm. The doctor measures these distances using hash marks printed on the scope itself, spaced 5 cm apart. To assess the hernia’s size and the condition of the valve between your esophagus and stomach, the scope is turned back on itself in a maneuver called retroflexion, giving a view looking upward from inside the stomach.
This retroflexed view is used to grade the hernia using a system called the Hill classification, which rates how well the valve at the esophagus-stomach junction is holding together. A grade IV finding, the most severe, means the hernia is large enough that the lining of the lower esophagus is visible from this reversed angle. The grading helps determine whether repair might be needed.
Esophageal Manometry: Measuring Pressure
Manometry doesn’t take pictures. Instead, it measures the pressure patterns along your esophagus using a thin, flexible tube inserted through your nose. Its primary purpose is evaluating how well your esophageal muscles contract, but it can also detect a hiatal hernia by identifying where two key structures sit in relation to each other: the lower esophageal sphincter (the muscular valve at the bottom of your esophagus) and the crural diaphragm (the part of the diaphragm that wraps around the esophagus).
In a person without a hernia, these two structures overlap completely on the pressure reading. This is classified as Type I. When a hernia develops, they begin to separate. A 1 to 2 cm gap is classified as Type II. A separation greater than 2 cm is Type III, at which point the pressure between the two structures drops to the level of stomach pressure, meaning the valve is no longer functioning effectively as a barrier against reflux.
Manometry is especially useful when surgery is being considered, because it reveals not just whether a hernia exists but how well the esophagus is still moving food downward. This information helps surgeons plan the right type of repair.
EndoFLIP: Assessing the Junction in Real Time
EndoFLIP is a newer tool sometimes used during an endoscopy to gather additional information. A thin catheter with a small balloon is placed at the esophagus-stomach junction. When the balloon is inflated, sensors measure the diameter of the opening and how the surrounding tissue responds to pressure. This tells your gastroenterologist whether the junction is unusually narrow, too loose, or abnormally stiff.
EndoFLIP isn’t a standalone diagnostic test for hiatal hernias. It’s typically added during an endoscopy when the clinical picture is complex, such as when you have both swallowing difficulty and reflux symptoms, and the team needs a fuller understanding of how the junction is functioning before recommending treatment.
How These Tests Work Together
There is no single mandated sequence for diagnosing a hiatal hernia. Which tests you get depends on your symptoms and what your provider is trying to learn. A barium swallow is often the first step when the main concern is anatomical: how big is the hernia, and what type is it? An upper endoscopy is preferred when the goal is also to check for reflux damage, ulcers, or precancerous changes to the esophageal lining. Manometry and pH monitoring (an acid-measuring probe left in the esophagus for up to 24 hours) are added when the question shifts from “is there a hernia?” to “is this hernia causing significant reflux or motility problems?”
For many people, a hiatal hernia is discovered incidentally during an endoscopy ordered for heartburn or during imaging done for an unrelated reason. In those cases, the hernia has already been found, and the diagnostic question becomes whether it’s causing problems that need treatment. Objective evidence of reflux or signs that stomach contents are reaching the airways (micro-aspiration) are the findings that typically move the conversation from monitoring toward repair.
Distinguishing a Hernia From Reflux Disease
A hiatal hernia and gastroesophageal reflux disease (GERD) are related but separate conditions. GERD is defined by stomach contents repeatedly flowing back into the esophagus. A hiatal hernia is a structural problem where the stomach has migrated upward. You can have one without the other, though larger hernias make reflux significantly more likely by disrupting the natural anti-reflux barrier.
The distinction matters for treatment. GERD without a hernia is usually managed with medication and lifestyle changes. A large hernia, particularly a paraesophageal type where a portion of the stomach has rolled into the chest, may need surgical repair regardless of reflux symptoms because of the risk of the stomach twisting or losing blood supply. pH monitoring, which measures actual acid exposure in the esophagus over a full day, is the test that most clearly separates reflux severity from hernia size, since a large hernia doesn’t always produce severe reflux and a small hernia sometimes does.