Can You See a Hiatal Hernia on a CT Scan?

CT scans can detect hiatal hernias, and standard CT reporting picks them up with a sensitivity of roughly 80%, which is comparable to or slightly better than endoscopy and barium swallow for the same condition. That number hides some interesting wrinkles, though. Small sliding hernias have a habit of appearing and disappearing between scans, larger paraesophageal hernias show up far more reliably, and newer measurement techniques on CT push detection rates above 90%. Whether a CT scan catches your hiatal hernia depends on the type of hernia, how the scan is performed, and what the radiologist is specifically looking for.

What Radiologists Actually See on the Scan

A hiatal hernia occurs when part of the stomach pushes up through the opening in the diaphragm where the esophagus passes through. On a CT image, the diaphragm appears as a thin muscular sheet, and the hiatus (the gap the esophagus travels through) is visible at the junction of the chest and abdomen. When a hernia is present, the radiologist can see stomach tissue sitting above the diaphragm in the lower chest, sometimes accompanied by fat or other abdominal contents. For larger hernias, the finding is unmistakable: a chunk of stomach clearly sitting in the chest cavity where it doesn’t belong.

The challenge comes with small sliding hernias, where only a small portion of the stomach has slipped upward. These can look subtle on a standard CT, particularly when the scan wasn’t ordered to evaluate the esophagus. CT imaging with oral contrast helps because it outlines the gastroesophageal junction and makes the displacement of the stomach more visible. Three-dimensional reformatted images and views in multiple planes (sagittal and coronal, not just the standard axial slices) also improve detection significantly.¹

The Disappearing Hernia Problem

One of the most striking findings in the CT literature on hiatal hernias is how often a hernia visible on one scan vanishes on the next. A large study examining over 3,000 adults found hiatal hernias in nearly half of participants during CT colonography, but when 123 of those people had a standard abdominal CT, the hernia had resolved in about 64% of cases.² A separate comparison study found a similar disappearance rate of around 58%, with small hernias vanishing more often than moderate ones.³

This happens because small sliding hiatal hernias are dynamic. The stomach slides up through the hiatus when intra-abdominal pressure increases and slides back down when it decreases. Patient position matters, breathing phase matters, and whether the bowel is distended matters. CT colonography inflates the colon with air or carbon dioxide, which raises abdominal pressure and pushes the stomach upward, making hernias more apparent. A routine abdominal CT taken while the patient lies flat and breathes normally may not capture that transient herniation. So if you’ve been told you have a hiatal hernia by one test but a CT comes back clean, the hernia didn’t necessarily resolve; it may just not have been present at the moment the scan was taken.

How Sensitive Is CT Compared to Other Tests?

A study comparing several diagnostic methods head to head found that standard CT reporting detected hiatal hernias with a sensitivity of about 80%, which was the highest among the conventional approaches tested. Endoscopy came in at roughly 75%, barium swallow at about 77%, and high-resolution manometry at around 71%.⁴ None of these are perfect, which is why clinicians sometimes use more than one modality when the diagnosis matters for surgical planning.

The same study tested a newer CT-based approach: measuring the actual surface area of the hiatal opening on cross-sectional images. This technique pushed sensitivity to about 95%, a substantial improvement over standard CT reads.⁴ The idea is that instead of relying on a radiologist’s visual impression of whether the stomach is herniated, you measure the hiatal opening itself. An enlarged opening suggests a hernia even if the stomach isn’t actively protruding at the moment of the scan. This approach is still relatively specialized and not part of routine CT reporting everywhere, but it illustrates how much the answer to “can CT see a hiatal hernia” depends on the technique used.

MRI offers a radiation-free alternative, with one study finding its sensitivity for detecting hiatal hernias was about 74%, compared to 80% for endoscopy in the same patient group. Interestingly, about a quarter of hernias found on MRI were only visible when the patient performed a Valsalva maneuver (bearing down), and those tended to be smaller.⁵ MRI has the advantage of real-time dynamic imaging, meaning it can capture the hernia sliding in and out during provocative maneuvers. CT, as a snapshot, doesn’t offer that.

Different Types Show Up Differently

Not all hiatal hernias are the same, and the type heavily influences how obvious it is on CT. The vast majority are Type I, or sliding hernias, where the gastroesophageal junction moves upward through the hiatus. These are the ones that come and go and can be subtle on imaging. Types II through IV are paraesophageal hernias, where a portion of the stomach (or in Type IV, the entire stomach along with other organs) herniates alongside the esophagus. These account for roughly 5 to 15% of all hiatal hernias.⁶

Paraesophageal hernias are generally far easier to spot on CT. A Type IV hernia, where the entire stomach and possibly the spleen, colon, or small bowel have migrated into the chest, is hard to miss on any imaging study. CT is considered particularly effective for these complex hernias because it shows exactly which organs have herniated, where they sit in the chest, and whether there are complications like twisting or obstruction.¹ While Type II through IV hernias tend to cause mechanical obstruction rather than acid reflux, they carry a higher risk of serious complications, which makes accurate imaging more important.

CT in Emergency Situations

CT really earns its keep when a hiatal hernia causes an acute emergency. Large paraesophageal hernias can twist (volvulus), strangulate, or even perforate, and these situations can mimic other life-threatening conditions. In one case report, a patient with a strangulated paraesophageal hernia was initially suspected of having a ruptured aortic aneurysm. The emergency CT revealed extensive free air in the abdomen and herniated organs in the chest, redirecting the diagnosis entirely.⁷

In another case, a large hiatal hernia compressed the heart severely enough to cause cardiac arrest in the emergency room, something the CT scan clearly demonstrated.⁸ These are rare scenarios, but they highlight a strength of CT that other tests don’t share: speed. A CT takes minutes, can be done in an emergency, and shows not just the hernia but all the downstream damage it may have caused. You can’t perform an endoscopy on a patient in cardiac arrest, but you can run them through a CT scanner.

A review of patients who received chest CT scans for suspected aortic dissection found that in about a fifth of cases where dissection was ruled out, an alternate diagnosis explained the symptoms. Hiatal hernia was the single most common alternate finding, appearing in seven of the 28 patients with alternative diagnoses.⁹ This means CT scans performed for entirely unrelated emergencies sometimes catch hiatal hernias incidentally, which raises its own set of questions about what to do with that information.

When Hiatal Hernias Are Found by Accident

Many hiatal hernias are discovered on CT scans that were ordered for something else entirely. A large population-based study using non-contrast cardiac CT scans in over 3,000 adults found a hiatal hernia prevalence of about 10%. Prevalence climbed steeply with age: roughly 2% in people in their fifties compared to nearly 17% in people in their eighties. Women were affected more often than men (about 13% versus 7%), and hernia presence was linked to proton pump inhibitor use, suggesting these people already had acid reflux symptoms being treated.¹⁰

The same study tracked 75 people with hiatal hernias over ten years and found that the median hernia area roughly doubled, growing from about 10 to 18 square centimeters. People whose hernias grew tended to have higher body mass index than those whose hernias shrank or stayed stable.¹⁰ This is one of the few longitudinal datasets on hiatal hernia progression, and it came from CT scans that weren’t looking for hernias at all. It suggests that for many people, hiatal hernias are a slowly progressive condition, and that weight management may play a role in slowing that progression.

An incidental finding creates a practical dilemma. A study of people with COPD found hiatal hernias on chest CT in about 12% of individuals, compared to 6% of smokers without COPD.¹¹ Those with hernias were more likely to be older, female, overweight, and already taking reflux medication, but having a hernia didn’t significantly change their rates of COPD flare-ups or hospitalizations. In other words, seeing a hernia on a CT scan doesn’t automatically mean it’s causing problems or needs intervention.

Hernia Size on CT Doesn’t Always Predict Symptoms

You might assume that a bigger hernia on CT means worse reflux, but the relationship isn’t that straightforward. A retrospective study looking at hernia size and reflux measurements found no statistically significant link between how large the hernia appeared and how severe the patient’s acid reflux scores were.¹² Some people with large hernias have minimal symptoms, while some with small hernias have severe reflux. The hernia impairs the anti-reflux barrier at the gastroesophageal junction, but other factors like esophageal motility, the tone of the lower esophageal sphincter, and body position contribute to symptoms independently.

Similarly, research measuring the hiatal surface area on CT found that people with reflux but no hernia didn’t have significantly larger hiatal openings than people without reflux or hernia.¹³ This reinforces the point that while CT can show you the anatomy, the anatomy alone doesn’t tell the whole story about someone’s symptoms. A CT finding of a hiatal hernia is a piece of the puzzle, not the whole diagnosis.

CT for Surgical Planning and Follow-Up

When surgery is being considered for a large or symptomatic hiatal hernia, CT takes on a different role. Surgeons want to know exactly how much of the stomach is in the chest, whether any other organs have herniated, and what the mediastinal anatomy looks like. For large hiatal hernias, preoperative CT has become a standard part of the workup because it gives the surgeon a map of what they’ll encounter during the operation. The detail that CT provides about surrounding structures, including blood vessels, the pericardium, and the lungs, isn’t available from endoscopy or barium studies.

After surgery, CT is also used to monitor for recurrence. Hernia repair, whether done laparoscopically or open, has a known recurrence rate, and CT can measure the hiatal opening to determine whether the stomach has begun to migrate upward again.¹⁴ Some recurrences are asymptomatic and found incidentally on follow-up imaging, which circles back to the earlier point about what to do with an anatomical finding that isn’t causing problems.

Tips That Improve Detection

If your doctor specifically wants to evaluate a hiatal hernia on CT, a few technical choices can make the scan more revealing:

Oral contrast: Drinking a contrast agent before the scan outlines the stomach and esophagus, making herniation easier to identify.
Multiplanar reconstruction: Viewing the images in coronal and sagittal planes, not just the standard axial slices, helps radiologists assess the diaphragmatic hiatus and see the relationship between the stomach and the diaphragm more clearly.
Valsalva maneuver: Having the patient bear down during scanning increases abdominal pressure and can reveal a hernia that’s otherwise hidden at rest. This technique is used more commonly with MRI and fluoroscopy but can be applied to CT as well.
Hiatal surface area measurement: Rather than just looking for herniated tissue, measuring the opening of the hiatus itself can detect enlargement even when the stomach isn’t actively protruding.

Not every facility applies all these techniques for routine scans. If a hiatal hernia is clinically suspected and the initial CT is negative, discussing these options with your doctor or asking whether a different imaging approach might be warranted is reasonable. A negative CT does not definitively rule out a hiatal hernia, especially a small sliding one. The scan captures a single moment in time, and the hernia may simply not have been present at that moment.

How CT Compares to the Classic Barium Swallow

For decades, the barium swallow was the go-to imaging test for hiatal hernias. You drink a chalky barium solution, and a series of X-ray images or fluoroscopic video captures the barium flowing through your esophagus and into your stomach, revealing the anatomy in real time. The advantage of barium swallow is its dynamic nature: the radiologist can watch the hernia slide up and down during swallowing, breathing, and straining. This makes it good at catching small, intermittent sliding hernias that a static CT might miss.

CT, on the other hand, offers superior anatomical detail of surrounding structures and is better at characterizing complex hernias involving multiple organs. It’s also faster, which matters in emergencies. The two tests are complementary rather than interchangeable. For a straightforward question about whether a small hernia exists and is contributing to reflux, a barium swallow or endoscopy may be more appropriate. For a complex hernia, preoperative planning, or an emergency presentation, CT is the stronger choice. The sensitivity numbers are fairly close across modalities, which means the clinical context and the specific question being asked often matter more than which test is objectively “best.”

1
PubMed Central. Diagnostic challenges of hiatal hernia Type IV: An imaging perspective
2
PubMed. Should small sliding hiatal hernias be reported at CT colonography?
3
PubMed. Incidental physiological sliding hiatal hernia: a single center comparison study between CT with water enema and CT colonography
4
Surgery Open Digestive Advance. CT oesophageal hiatal surface area measurements: An objective and sensitive means of hiatal hernia detection
5
PubMed. Hiatal hernias in patients with GERD-like symptoms: evaluation of dynamic real-time MRI vs endoscopy
6
Insights into Imaging. Imaging and grading of hiatal hernia
7
PubMed Central. Perforated gastric corpus in a strangulated paraesophageal hernia: a case report
8
PubMed Central. Cardiopulmonary arrest secondary to compression of the heart owing to esophageal hiatal hernia: a case report
9
PubMed. Chest CT scanning for clinical suspected thoracic aortic dissection: beware the alternate diagnosis
10
BMJ Open Gastroenterology. Hiatal hernia prevalence and natural history on non-contrast CT in the Multi-Ethnic Study of Atherosclerosis (MESA)
11
PubMed Central. Hiatal Hernia on Chest High-Resolution Computed Tomography and Exacerbation Rates in COPD Individuals
12
PubMed Central. Hiatal Hernia Size and Reflux Parameters in Gastro-Oesophageal Reflux Disease: Evidence From a Retrospective Cohort
13
PubMed Central. Multiplanar MDCT measurement of esophageal hiatus surface area: association with hiatal hernia and GERD
14
PubMed. Hiatal hernia recurrences after laparoscopic surgery: exploring the optimal technique