Hiatus hernia may be broadly classified into sliding hernia and paraesophageal hernias. Sliding hernia is also called type I hernia and paraesophageal hernia is divided into three subtypes including type II, type III and type IV.

• Hiatus hernia may be classified into four subtypes:^[1][2]
  • Type I or sliding hernia: Approximately 95% of all hiatal hernias are type 1 sliding hernias. Type I sliding hernia characterized by the displacement of the gastroesophageal (GE) junction just above the diaphragm into the thoracic cavity.
  • Type II Paraesophageal hernias: A paraesophageal hernia contains a hernia sac hence is a true hernia. Type II hernias are characterized by upward displacement of the gastric fundus through phrenoesophageal membrane, while the gastroesophageal junction remains attached to the preaortic fascia and the median arcuate ligament.
  • Type III Paraesophageal hernia: Type III hernia, is like a combination oftype I and II, having a part of the stomach that has herniated through the hiatus, but also have an abnormal placement of the gastroesophageal junction in the thoracic cavity.
  • Type IV Paraesophageal hernia: Type IV hernia is associated with a large defect in the phrenoesophageal membrane and it may contain stomach along with other contents including colon, spleen, pancreas, or small intestine.