A condition in which part of the stomach pushes up through the diaphragm muscle. In hiatus hernia, part of the stomach pushes into the chest cavity. It enters via an opening where the food tube (oesophagus) passes on its way to the stomach. Hiatus hernias can have no symptoms. In some cases, they may be associated with heartburn and abdominal discomfort. Hiatus hernias may not require any treatment. Some are treated with drugs and a few types need surgical repair.