What condition involves the fundus of the stomach pushing through the esophageal hiatus of the diaphragm?

The condition characterized by the fundus of the stomach pushing through the esophageal hiatus of the diaphragm is indeed a paraesophageal hiatus hernia. This type of hernia occurs when a part of the stomach bulges through the diaphragm alongside the esophagus, but unlike in a sliding hiatus hernia, the esophagus and stomach maintain their relative positions. The main concern with a paraesophageal hernia is that it can lead to complications such as strangulation, as the stomach can become trapped in the thoracic cavity, leading to reduced blood supply.

In contrast, a sliding hiatus hernia refers to the situation where the gastroesophageal junction and part of the stomach slide up through the hiatus. While this is more common and can also lead to gastroesophageal reflux disease, it does not involve the fundus moving through the diaphragm in the same way. Gastroesophageal reflux disease (GERD) primarily involves the backflow of stomach acid into the esophagus, often as a result of a sliding hiatus hernia rather than a paraesophageal hernia. Peptic ulcer disease is related to sores in the lining of the stomach or duodenum and is unrelated to the mechanical movement of the stomach through the diaphragm.