**6. Biliary and duodenal complications**

Biliary stricture (BS) and duodenal stenosis (DS) are uncommon complication of AP. Pathogenesis of these events is strictly related to the anatomical position between the pancreatic head, the common bile duct and the duodenum. BS and DS are, in most cases, early and transient conditions associated to severe inflammation [65]. The main causes for temporary BS are inflammatory oedema and pseudocyst formation and enlargement in the area proximal to the pancreatic head that create a compression of the common bile duct, thus causing jaundice, nausea, vomit, abdominal pain, pruritus, and fatigue to the patient [66].

A duodenal early complication is gastric outlet obstruction related to the abnormal peristaltic wave and following ileus caused by the severe inflammation and the possible compression of the duodenal loop by the enlarged neck of the pancreas that cause a lumen obstruction [67].

BS ad DS usually solve with a conservative treatment intended to overcome the acute inflammatory phase. Pseudocyst management is resumed in previous chapters.

In many studies, late BS is associated to pancreatic duct disruption (PDD) with pancreatic juice leakage when duct of the head/neck of pancreas is involved in pancreatic necrosis [68]. When PDD is suspected, contrast-enhanced CT should be performed to confirm it and after that an endoscopic retrograde cholangiopancreatography (ERCP) to localize the leakage and positioning a stent [69]. If this procedure failed, and a progression of the common duct stricture has developed, surgical procedure is indicated [53].

The process that leads a transient DS to an irreversible one is still unclear. Literature suggests that the underlaying cause is a possible ischemic and thrombotic event. Indeed, inflammation may induce arterial narrowing and/or thrombosis of the pancreaticoduodenal circulation producing local ischemia and resulting in chronic fibrosis [70]. Patients who present intermittent symptomatic episodes of upper gastrointestinal tract obstruction should undergo surgical bypass, chosen considering the pathophysiology (gastrojejunostomy or gastroenterostomy with vagotomy to prevent marginal ulcer)[71].
