A duodenal diverticulum (the plural of which is diverticula) is a pouch attached to the duodenum, the first part of the small intestine just past the stomach.
There are two types of duodenal diverticula. The common type which is present in some individuals, is one that sticks out from the duodenum, similar to the more common colonic diverticula. This is referred to as an "extramural" diverticulum. Extramural diverticula may vary in size from a few millimeters to a few centimeters. They usually are located in the area around the Papilla of Vater where the bile and pancreatic ducts enter the duodenum.
A second, rare type of diverticulum is referred to as an "intramural" diverticulum. It does not protrude from the duodenum. Rather, it protrudes into the duodenal lumen (the hollow inside of the duodenum through which digesting food flows). Both types of diverticula, extramural and intramural, communicate with the lumen of the duodenum so that contents of the duodenum can enter the diverticulum.
The cause of extramural diverticula is not definitively known; however, they are believed to be acquired (not present from birth) due to a herniation (protrusion) of the duodenum through a defect in the muscle of the wall of the duodenum, perhaps in an area where arteries pass through the intestinal muscle to nourish the lining of the intestine.
Extramural diverticula usually cause no symptoms. Occasionally, they may rupture (just like colonic diverticula) and lead to a pocket of inflammation adjacent to the duodenum with or without infection. This may result in all the signs and symptoms of intra-abdominal inflammation including pain, fever, and abdominal tenderness.
If the diverticulum is very close to the Ampulla of Vater, patients more frequently develop gallstones, particularly in the bile duct, and may develop all of the complications of gallstones:
Pancreatitis also may occur. These complications are believed to be due to interference by the diverticula with the normal function of the bile and pancreatic ducts.
If treatment is necessary, extramural diverticula can be surgically removed from the outside of the duodenum. The diverticula also may be inverted into the lumen of the duodenum and removed through an incision in the wall of the duodenum. (Sometimes, the diverticulum is inverted but left attached to the wall of the duodenum and protruding into the duodenum.)
The cause of intramural diverticula is not clear; however, they are believed to be congenital, that is, present from birth, and may occur as a developmental abnormality of the intestine in the fetus.
Intramural duodenal diverticula most commonly cause obstruction of the duodenum when the diverticulum fills with ingested material. They are commonly diagnosed by barium x-ray studies of the upper gastrointestinal tract but also are seen with upper gastrointestinal endoscopy.
Intramural diverticula are surgically removed through an incision in the wall of the duodenum, although there are reports of treatment using non-surgical, endoscopic means to incise or open up the diverticula so that material does not collect within them.