Diverticula are herniations in the wall of either the esophagus or intestines. The most common type of diverticula are found in either the large or small intestine and may be the result of a congenital deformity or they may be acquired. Congenital diverticula are herniations of the entire thickness of the intestinal wall, while the more common acquired diverticula consist of herniations of the thinner mucosa generally at the site of an artery which provides nutrients to the area.(1)

The most common location for diverticula in the small intestine, is either in the middle part of the small intestine called the jejunum or in the first part of the small intestine called the duodenum. Most of the time, diverticula do not produce any symptoms that are noticeable and are usually discovered almost accidentally when the individual has reason to have an upper GI x-ray. When symptoms do occur, it is because the diverticula are close to other structures or because they have become inflamed.

A patient with multiple jejunal diverticula may have not been able to absorb nutrients properly from the food that they eat. This occurs as a result of bacterial overgrowth within the diverticula. Such bacterial overgrowth results in mucosal damage and primarily affects the absorption of vitamin B12. Another type of diverticular disease is called Meckel's diverticulum. This is a congenital abnormality of the digestive tract. This condition is usually found in children and teenagers, however they are rarely symptomatic after age five.

Diverticula of the large intestine occur most frequently in the lower part of the large intestine called the sigmoid colon. Sometimes they occur in the first part of the large intestine called the proximal colon, but this does not happen quite as often. In western populations such as in the US, the occurrence increases with age. While the exact mechanism is unknown, it is thought to involve increased pressure from the inside of the intestine.

Since colonic diverticula are rare in underdeveloped nations, it has been postulated that the formation may be due at least in part to highly refined western diets, which generally lack in dietary fiber or roughage. In such diets, the feces contain less bulk, which causes the colon to narrow and requires an increased pressure to move the smaller fecal mass. As with small intestinal diverticula, they usually do not have any symptoms and are often found incidentally during colonoscopy or barium enema.

Diverticulitis can be defined as inflammation that occurs in or around the diverticular sac. The cause of diverticulitis is probably mechanical, related to the retention of undigested food residues and bacteria, which may form a hard mass called a fecalith.(1) This compromises blood supply to the thin-walled sac and makes it more susceptible to invasion by unwanted bacteria. Diverticulitis occurs more often in men than women, and occurs most often in the left side of the colon as opposed to the right side. This seems to indicate that diverticulitis is related to the increased pressure involved in pushing more solid fecal material found in the sigmoid and descending colon. Some attacks are accompanied by minimal pain and seem to heal spontaneously, while others can be severe.