A hiatal hernia is a condition where the upper part of the stomach bulges through the diaphragm into the chest cavity. The diaphragm is the muscle that separates the chest from the abdomen, and it has a small opening (hiatus) through which the food tube (esophagus) passes before connecting to the stomach. In a hiatal hernia, the stomach pushes up through that opening and into the chest. There are four types of hiatal hernias, with the vast majority being type I, or sliding hiatal hernias. Hiatal hernias are common, especially as people get older, and they may be linked to reflux (backflow) of gastric acid from the stomach into the esophagus.

Some people with hiatal hernias may not experience any symptoms, while others may have heartburn, chest pain, bloating, burping, trouble swallowing, bad taste in the mouth, upset stomach, vomiting, or backflow of food or liquid from the stomach into the mouth. Shortness of breath may also occur if the hernia is compressing the lungs. In rare cases, severe pain in the chest or belly, persistent upset stomach, vomiting, or inability to pass gas or poop may indicate a strangulated hernia or an obstruction, which are medical emergencies.

The exact cause of hiatal hernias is not known, but they may be due to weakness of the supporting tissue. Risk factors for hiatal hernias include being born with a larger hiatal opening than usual, injury to the area, changes in the diaphragm as people age, and a rise in pressure in the belly due to pregnancy, obesity, coughing, lifting something heavy, or straining on the toilet.

To diagnose a hiatal hernia, a doctor may do tests such as a barium X-ray or CT of the upper digestive tract to identify the location and positioning of the gastric organs. Treatment is available for hiatal hernias that cause symptoms, and options include lifestyle changes, medications, and surgery.