Hiatal hernias are defined as herniation of the stomach into the chest, as the stomach pushes up from the abdomen into the chest cavity. Herniation occurs through the diaphragmatic esophageal hiatus, which is an opening in the diaphragm through which the esophagus connects to the stomach.
There are four types of hiatal hernia:
Type I hiatal hernia is the most common type. It is also called a sliding hiatal hernia. This type accounts for about 95 percent of all hiatal hernias. In this type of hernia, the gastroesophageal junction is herniated into the chest cavity, as shown in the image below.
Type II hiatal hernia is also called a paraesophageal hiatal hernia, in which the stomach herniates through the diaphragmatic esophageal hiatus alongside the esophagus. In the type II or "pure" paraesophageal hernia, the gastroesophageal junction remains below the hiatus and the stomach rotates in front of the esophagus and herniates into the chest (see image below). If more than 30 percent of the stomach herniates into the chest, the condition is also called a giant paraesophageal hernia.
"Pure" type II paraesophageal hernia seldom occurs. Paraesophageal hiatal hernias make up less than 5 percent of all hiatal hernias, but account for most of the hiatal hernia complications.
Type III hiatal hernias are combined hernias in which the gastroesophageal junction is herniated above the diaphragm and the stomach is herniated alongside the esophagus. The majority of paraesophageal hernias are type III (see image below).
In type IV hiatal hernias, other organs in addition to the stomach (colon, small intestine, spleen) also herniate into the chest (see image below).
By Farzaneh Banki, M.D.
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