Hiatal hernias occur when contents of the abdominal cavity protrude through the esophageal hiatus of the diaphragm. Factors that contribute to the development of a hiatal hernia include an enlargement of the esophageal hiatus due to developmental defects, an increased abdominal thoracic pressure gradient, and the depletion of elastic fibers in the phrenoesophageal membrane with aging. There are four different types of hiatal hernias and management varies depending on the type.
Type I, also known as a sliding hernia, is a simple displacement of the gastroesophageal junction into the thoracic cavity. The stomach remains in the abdominal cavity. This is the most common type of hiatal hernia, accounting for about 95% of all hiatal hernias. Types II-IV are classified as paraesophageal hernias. Type II occurs when the gastroesophageal junction maintains its position but the gastric fundus herniates through the diaphragmatic hiatus. Type III has both the gastroesophageal junction and the stomach herniate above the diaphragm. When more than 30% of the stomach is herniated into the thoracic cavity, it is termed a “giant” paraesophageal hernia. A patient has a type IV hernia when other organs, such as the colon, in addition to the stomach herniate above the diaphragm.