Ultrasound can detect a hiatal hernia, though it’s not the go-to test most doctors order for this purpose. A standard abdominal ultrasound can show a widened opening in the diaphragm where the stomach pushes through, and research has found a clear, measurable difference between people with and without the condition. In people with a sliding hiatal hernia, the opening at the diaphragm measured about 32 mm on ultrasound, compared to roughly 12 mm in people without one. That said, barium swallow X-rays and endoscopy remain the primary diagnostic tools.
What Ultrasound Can Show
A transabdominal ultrasound, the same type used to examine your gallbladder or kidneys, can visualize the area where your esophagus meets your stomach and passes through the diaphragm. When a hiatal hernia is present, the sonographer can often see that part of the stomach has shifted upward through this opening. The width of the hiatal opening itself is the key measurement. Research from a controlled study found the difference between a normal hiatus (about 11.6 mm) and one with a sliding hernia (about 31.7 mm) was statistically unmistakable.
Ultrasound can also assess the position of the lower esophageal sphincter relative to the diaphragm and the angle where the esophagus joins the stomach. These landmarks help a radiologist determine whether the anatomy has shifted in a way consistent with a hernia.
Why It’s Not the First Test Ordered
Despite its ability to detect hiatal hernias, ultrasound isn’t the standard first-line test for a few reasons. There is no standardized protocol for how the exam should be performed, including whether the patient should be lying down or standing up. Since a hiatal hernia can slide in and out of position with breathing, swallowing, and changes in posture, the timing of the scan matters. A hernia that’s present one moment may reduce itself the next, making it easy to miss.
Larger hernias are generally straightforward to spot, while smaller ones are frequently missed or misdiagnosed. Body factors like excess abdominal fat and intestinal gas can also obscure the view, since ultrasound waves don’t travel well through air or thick tissue layers. This makes the test less reliable in some patients.
The established diagnostic tools, barium swallow X-rays and upper endoscopy, give a more consistent and detailed picture. A barium swallow shows the hernia in real time as you drink a contrast liquid, and endoscopy lets a gastroenterologist directly see the anatomy. Manometry and CT scans are also used in certain situations.
When Ultrasound Is Especially Useful
Ultrasound has a clear advantage in one population: infants and young children. Because it involves no radiation and no sedation, it’s a practical first step when a baby presents with vomiting, difficulty feeding, or other symptoms that could point to a hernia or several other conditions. In one documented case, ultrasound raised the initial suspicion of a hiatal hernia in a 4-month-old with vomiting and swallowing problems, which was later confirmed by standard methods. Ultrasound is also valuable in ruling out other causes of vomiting in infants, like pyloric stenosis, during the same exam.
That said, even in pediatric care, current guidelines from 2018 note that ultrasound doesn’t have a routine role in diagnosing gastroesophageal reflux disease in children. Its strength lies more in screening and in narrowing down a list of possible diagnoses than in making the final call.
Endoscopic Ultrasound for Surgical Planning
A more specialized form of ultrasound, called endoscopic ultrasound (EUS), offers a much more detailed look. This involves passing a small ultrasound probe on the tip of an endoscope down into the esophagus, which puts the sensor right next to the structures in question. EUS can measure the exact distance between the muscular pillars of the diaphragm, determine the size and cross-section of the hernia sac, and assess how the junction between the esophagus and stomach sits relative to the diaphragm.
This level of detail is typically reserved for surgical planning rather than initial diagnosis. When a surgeon needs to know the precise dimensions of a hernia before choosing a repair technique, EUS provides measurements that standard imaging may not capture as accurately.
What to Expect if a Hernia Shows Up Incidentally
Many hiatal hernias are found by accident during an ultrasound ordered for something else entirely, like an abdominal pain workup or a gallbladder check. If a radiologist notes a widened hiatal opening or stomach tissue above the diaphragm, your doctor will likely recommend a follow-up test to confirm. This usually means a barium swallow or an upper endoscopy, both of which give a clearer picture of the hernia’s size, type, and whether it’s causing any damage to the esophageal lining.
Researchers have suggested that including ultrasound in the initial diagnostic steps for hiatal hernias could reduce the need for more expensive procedures. For now, though, its role remains supplementary. Ultrasound is a safe, radiation-free, and relatively inexpensive way to raise suspicion of a hiatal hernia, but confirmation with a more established method is standard practice.