A hiatus hernia, or hiatal hernia, is when part of the stomach squeezes up into the chest through an opening (“hiatus”) in the diaphragm.

The diaphragm is a large, thin sheet of muscle between the chest and the abdomen (tummy).

Hiatus hernia and heartburn

A hiatus hernia itself rarely has any noticeable symptoms. However, it can cause a problem called gastro-oesophageal reflux disease (GORD).

GORD is where stomach acid leaks into the oesophagus (the tube that carries food to the stomach). It can occur if a hiatus hernia prevents the valve at the bottom of the oesophagus from working properly.

Your oesophagus can become severely irritated, because it’s not protected against stomach acid. This can cause symptoms such as heartburn, chest pain, an unpleasant sour taste in your mouth, and swallowing problems (dysphagia).