A hiatal hernia is a condition in which part of the stomach protrudes through the diaphragm from the abdomen into the chest. The diaphragm is a thin sheet of muscle that is involved in breathing. It separates the abdomen from the chest.
Hiatal hernias are common after middle age.
They do not often cause problems. The cause of hiatal hernias is not known. Many people with a hiatal hernia never have any symptoms. However, in some people, stomach acid and digestive juices move up into the esophagus via the bulge of the stomach through the diaphragm. Because many hiatal hernias do not cause symptoms, they are often discovered during an investigation for other conditions.