Gastrointestinal System / Nutrition

Heartburn and acid regurgitation, often worse when supine or after meals. First step is lifestyle modification plus an empiric trial of a proton pump inhibitor (PPI); endoscopy is reserved for alarm features.

Dysphagia, odynophagia, unintentional weight loss, GI bleeding (hematemesis/melena), iron-deficiency anemia, persistent vomiting, or onset of new symptoms at age >60. These warrant EGD to exclude malignancy or complicated disease.

Metaplastic replacement of the normal squamous esophageal epithelium with columnar (intestinal-type) epithelium due to chronic GERD. It is a premalignant lesion that increases the risk of esophageal adenocarcinoma and requires endoscopic surveillance.

Progressive dysphagia to both solids AND liquids, regurgitation of undigested food, and chest pain. Barium swallow shows a 'bird-beak' tapering of the distal esophagus; esophageal manometry is confirmatory, showing incomplete LES relaxation and absent peristalsis.

Degeneration of inhibitory ganglion cells (myenteric/Auerbach plexus) in the distal esophagus and LES, leading to failure of LES relaxation and loss of peristalsis.