Diverticulosis is characterized by the presence of small, abnormal pouches, or diverticula, in the intestinal wall. The pouches may be birth defects, particularly if they involve all the layers of the intestinal wall, but they most often develop as a person ages. The sacs can range in size from small to large and may occur singly (diverticulum) or in large numbers. Most often, diverticula are small and single.

Although diverticulosis refers specifically to the presence of diverticula in the colon, sacs may appear in the organ walls nearly anywhere in the digestive tract. Other forms of diverticula include:

• Zenker’s diverticula. These occur in the upper portion of the esophagus, near the pharynx. They are generally believed to be caused by motor esophageal disorders. Pouches may also develop in the mid or lower esophagus and may cause difficulty swallowing (dysphagia), coughing, bad breath (halitosis) and the regurgitation of undigested food that had been trapped in the diverticula.
  
  
• Gastric diverticula. These are pouches in the stomach. Those located near the opening of the esophagus are typically present at birth. Sacs located elsewhere in the stomach may result from peptic disorders.
  
  
• Meckel’s diverticula. These are sacs in the small intestine, usually near the end of the ileum and near the beginning of the colon. They are typically present at birth and may cause abdominal pain. They rarely cause rectal bleeding.
  
  
• Duodenal diverticula. Sacs in the duodenum are usually located near the opening of the common bile duct and pancreatic duct. They may contribute to the formation of gallstones or acute pancreatitis is some patients.