Hiatus hernia. Illustration of a sectioned view through the stomach (bottom), diaphragm (band across centre), and the lower part of the oesophagus (gullet, upper left), in a case of a hiatus hernia. This is where the upper portion of the stomach protrudes from the abdominal cavity into the chest cavity through the existing hole in the diaphragm where the oesophagus connects to the stomach. This type of hernia is relatively common. Surgery is only required in severe cases or where complications develop. Complications include gastro-oesophageal reflux of gastric acid into the oesophagus, causing inflammation and ulceration of the oesophagus.