of the duodenal tract which is proximal to the narrowing caused by the annular pancreas, and the dilatation of the duodenal portion distal to the anomaly. An abdominal CT scan or an MRI allows to highlight the narrowing of the descending duodenal tract and the ring of pancreatic tissue surrounding the duodenum: this ring can be complete or, in patients with an incomplete annular pancreas, extended in a postero-lateral or anterolateral direction with respect to the second part of the duodenum. ERCP or MRCP with secretin allow precise delineation of the anatomical structure and in particular a good visualization of pancreatic ducts, as well as a careful analysis of pancreatic secretion into the duodenum lumen. Treatment In neonates, treatment for relief of obstruction usually is bypassing the obstructed segment of duodenum by duodeno-jejunostomy. In adults, due to the minor duodenal mobility, the approach is laparoscopic gastrojejunostomy or duodenojejunostomy. References External links Congenital disorders of digestive system