C Hiatal hernia and gastric reflux
Definitions
Hiatal hernia
A hiatal hernia consists of a defect in the diaphragm that allows a portion of the stomach to migrate upward into the thoracic cavity. Two types of esophageal hiatal hernias are the sliding type (type I), which is formed by the movement of the upper stomach through an enlarged hiatus, and the paraesophageal type (type II), in which the esophagogastric junction remains in normal position but all or part of the stomach moves into the thorax and assumes a paraesophageal position. A third type of hiatal hernia (type III) has been identified that combines the features of a sliding and a paraesophageal hernia. A fourth type of hiatal hernia (type IV) occurs when other organs, such as the colon or small bowel, are contained in the hernia sac that is formed by a large paraesophageal hernia. Hiatal hernia and peptic esophagitis often exist concurrently, although one does not cause the other.
Gastric reflux
Gastric reflux relates to a reduced lower esophageal sphincter tone, which can increase the risk for regurgitation and aspiration. Reflux can occur without the presence of hiatal hernia. The lower sphincter is a physiologic sphincter with no specialized musculature. Tone is 15 to 35 mmHg.