: an abnormal pouch or sac opening from a hollow organ (as the colon or bladder)
: a blind tube or sac branching off from a cavity or canal of the body <the liver is an anterior diverticulum of the intestine—Gordon Alexander>
Small pouch or sac formed in the wall of a major organ, usually the esophagus, small intestine, or large intestine (the most frequent site of problems). In the large intestine, feces pushed into a pouch can make it bulge out from the colon wall, a condition known as diverticulosis, which has no symptoms. In the more serious condition called diverticulitis, those sacs become inflamed, causing pain and tenderness, chills, and sometimes fever. Mild cases need only bed rest and antibiotics. In severe cases, perforation or rupture of the colon wall at the diverticulum can cause peritonitis. Rupture may require colostomy. Meckel diverticulum, a congenital malformation of the upper intestine that causes bleeding and inflammation, may require surgical removal.