Hiatal Hernia

A hiatal hernia is the abnormal protrusion of the stomach or other abdominal organs through the esophageal hiatus of the diaphragm into the thoracic cavity.

Normally, the gastroesophageal junction (GEJ) lies below the diaphragm and is supported by the phrenoesophageal membrane, the diaphragmatic crura, and connective tissues. Weakening of these structures—due to aging, congenital defects like a short esophagus, or increased intra-abdominal pressure from coughing, obesity, pregnancy, or heavy lifting—enlarges the hiatus, allowing herniation of the GEJ and stomach into the chest.

Types of Hiatal Hernia

Hiatal hernias are classified into four types.

• Type I (sliding hernia), the most common, involves upward movement of the GEJ and upper stomach.
• Type II (paraesophageal hernia) occurs when the gastric fundus herniates alongside the esophagus, leaving the GEJ in place and carrying a risk of volvulus and ischemia.
• Type III (mixed hernia) combines features of Types I and II, with herniation of both the GEJ and the stomach.
• Type IV (complex hernia) is the most severe, involving herniation of additional organs such as the colon or small intestine due to a large defect.

Pathophysiological Effects

All types disrupt the anti-reflux barrier, which includes the LES, crural diaphragm, intra-abdominal esophagus, and angle of His. Herniation lowers LES pressure, shortens the intra-abdominal esophagus, and flattens the angle of His, promoting reflux. Increased transient LES relaxations and reduced acid clearance further elevate esophageal acid exposure, leading to GERD and complications such as esophagitis, Barrett’s esophagus, and esophageal adenocarcinoma.