Gastroesophageal Reflux Disease (GERD)
- Gastroesophageal Reflux Disease (GERD) refers to an etiology of esophagitis caused by repeated reflux of stomach acid into the lower esophagus. GERD is extremely common and is thought to occur in nearly 10% of adults. Although the symptomology of GERD is largely a nuisance, long-term presence of GERD significantly increases the risk of esophageal carcinoma, especially the adenocarcinoma subtype.
- Normally, gastric acid does not reflux into the esophagus because the tone of the Lower Esophageal Sphincter (LES) is greater than the gastric intraluminal pressure. Consequently, the LES is closely apposed, thus blocking reflux of stomach contents. GERD is thought to occur either by reduced tone in the LES or increased gastric intraluminal pressures.
- Decreased LES Tone
- In most cases, decreased LES tone is thought to be idiopathic; however, a variety of secondary causes of LES incompetence also exist such as systemic sclerosis in which the LES becomes infiltrated with fibrotic tissue.
- Increased Gastric Intraluminal Pressure
- Global increases in gastric inraluminal pressures tend to occur in pregnancy and in obese individuals due to the presence of large intra-abdominal masses. Increases in intra-gastric volume such as after the ingestion of a large meal can also result in rising gastric intraluminal pressure. Finally, localized increases in pressure may occur in the gastric antrum near the gastroesophageal junction in those with sliding hiatal hernias or when individuals are in a recumbent position.
- The morphology of GERD depends on the duration of contact between the esophageal mucosa and refluxed stomach contents. Consequently, the amount of refluxed material, how frequently reflux occurs, and how quickly refluxed material is cleared are all variables. Mild cases of GERD may only display some hyperemia of the esophageal mucosa without any significant histological changes. As exposure increases, a histological picture of esophagitis appears, termed "Reflux Esophagitis", characterized by an eosinophilic infiltration of the esophageal mucosa along with hyperplasia of the esophageal epithelial basal layer. In severe cases, overt ulceration of the esophageal mucosa will occur which, if repeated frequently, will progressively heal along the lines of intestinal epithelial architecture, heralding Barrett Esophagus.
- The typical presenting scenario of GERD is the sensation of heartburn and the presence of a sour taste in the mouth especially after large meals or recumbency, although chest pain can also be felt. However, a variety of more ominous complications can arise due to long-term presence of GERD. The most feared complication is the development of Barrett Esophagus and its progression to overt esophageal carcinoma, usually the adenocarcinoma subtype. However, patients may also display signs of upper GI Bleeding such as melena or hematemesis. Finally, repeated inflammatory injury to the esophagus may result in its fibrotic healing, leading to esophageal stricture and development of dysphagia.