Classification

Type I: sliding hiatal hernia

• Most common type (95% of cases)

• The GEJ and the gastric cardia slide up into the posterior mediastinum.

• The gastric fundus remains below the diaphragm (hourglass stomach)

Type II: paraesophageal hiatal hernia

• Part of the gastric fundus herniates into the thorax.

• The GEJ remains in its anatomical position below the diaphragm.

Type III: mixed hiatal hernia

• Mix of types I and II

• The GEJ and a portion of the gastric fundus prolapse through the hiatus.

Type IV: complex hiatal hernia

• Herniation of any abdominal structure other than the stomach (e.g., spleen, omentum, or colon)

• Rarest type

• Esophageal hiatus

  • Central opening of the diaphragm, which allows the esophagus to pass through into the peritoneal cavity; forms the upper part of the esophageal sphincter and the reflux barrier

  • Formed by:

    • Left and right paravertebral tendinous crura

    • Median arcuate ligament

• Gastroesophageal junction (GEJ)

  • Normally lies at the level of the esophageal hiatus

  • Phrenoesophageal ligament (PEL) attaches to the esophagus at the GEJ

    • Peritoneal fold that encircles the distal portion of the esophagus and gastroesophageal junction and connects them to the peritoneal surface of the diaphragm

    • Closes the esophageal hiatus and helps maintain the intra-abdominal position of the GEJ

• Predisposing factors lead to laxity of the esophageal hiatus, e.g.:

  • Advanced age → phrenoesophageal ligament weakens

  • Smoking → loss of elastin fibres in the diaphragmatic crura

  • Obesity → deposition of fat in and around the crura → widened hiatus

• Relative negative intrathoracic pressure and the lax hiatus → herniation of the abdominal contents into the thorax → loss of reflux barrier + compromised fluid emptying of distal esophagus → gastroesophageal reflux disease (GERD)