A hiatal hernia occurs when the upper part of the stomach bulges through the diaphragm into the chest cavity. The exact cause of hiatal hernia is not known, but it may be due to weakened muscle tissue that allows the stomach to bulge up through the diaphragm. Some factors that may contribute to the development of hiatal hernia include:

• Age-related changes in the diaphragm
• Injury to the area, such as after trauma or certain types of surgery
• Being born with an unusually large hiatus
• Persistent and intense pressure on the surrounding muscles, such as while coughing, vomiting, straining during a bowel movement, or lifting heavy objects

Most hiatal hernias do not cause symptoms, but they can lead to chronic acid reflux, which can damage the esophagus over time. Symptoms of hiatal hernia may include chest pain, heartburn, difficulty swallowing, burping, feeling nauseous, vomiting, and backflow of acid or stomach contents into the esophagus or throat. Treatment for hiatal hernia may include lifestyle changes, medication, or surgery.