What is a hiatal hernia, and what types are there?
A hiatal hernia is a herniation of abdominal organs (most often a portion of the stomach and less often portions of the mesenteric fat or of other organs) through the esophageal hiatus of the diaphragm. There are two types of hiatal hernias.
An axial hiatal hernia is the most common type (98%), where the gastroesophageal junction is located above the esophageal hiatus. This type is often seen in the setting of gastroesophageal reflux (GER) and may either occur as a sliding subtype (which is only seen when the patient is recumbent) or as a fixed subtype.
A paraesophageal hiatal hernia is an uncommon type (2%), where the gastroesophageal junction remains below the esophageal hiatus but a portion of the stomach (most commonly the gastric fundus) herniates through the esophageal hiatus alongside the distal esophagus. This type is not associated with GER but is associated with an increased risk of gastric incarceration, strangulation, and perforation.