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Duodenal diverticula are outpouchings from the duodenum that represent herniation of the mucosa and submucosa through the muscular wall. Diverticula are uncommon before the age of 50 years but can be demonstrated in 10–15% of the population by the age of 80 years. At least 75% of diverticula are located within 2 cm of the ampulla of Vater and have been called juxtapapillary diverticula. The remainder occur at the accessory ampulla or elsewhere in the duodenum. There is now persuasive evidence for an association between bile duct stones and duodenal diverticula, particularly bile duct stones in the absence of gallbladder stones (primary bile duct stones). This association is likely to reflect a degree of bile stasis that is often accompanied by bacterial contamination of bile. Diverticula have also been associated with idiopathic pancreatitis. Diverticula are best demonstrated by duodenal endoscopy using a side-viewing endoscope or by barium meal radiographs. With computed tomography (CT) scans and magnetic resonance imaging scans, larger diverticula are seen as lesions on the medial wall of the second part of the duodenum that typically contains gas.

The patient illustrated below was a 70-year-old woman who was investigated because of intermittent pain in the upper abdomen, particularly after meals. Blood tests revealed a mild elevation of bilirubin, a minor elevation of alanine aminotransferase and amylase and a moderate elevation of alkaline phosphatase (359 u/l). On an upper abdominal ultrasound study, intrahepatic and extrahepatic bile ducts were mildly dilated and she had a distended gallbladder without gallbladder stones. A contrast-enhanced CT scan after oral contrast showed a hypodense lesion, 3 cm in diameter (arrow), in the region of the head of the pancreas (Figure 1). Small amounts of gas were demonstrated within the lesion on some slices. She also had dilatation of the bile duct and main pancreatic duct and distension of the gallbladder. A barium radiograph showed only partial filling of a diverticulum on the medial wall of the second part of the duodenum (Figure 2). At endoscopy, the diverticulum was filled with impacted food residue. Following endoscopic extraction, her symptoms resolved and liver function tests returned to normal. Impacted food residue within a diverticulum is a rare cause of cholestasis as duodenal diverticula have a relatively wide orifice.