Introduction Embyrologic deformity of the pancreas Pancreas normally develops from one dorsal and two ventral buds Ventral buds normally rotate with duodenum, but if they fail to do so, annular pancreas may form Three theories to explain this: Adherence of the ventral bud to the duodenal wall prior to rotation, resulting in its persistence and encirclement of the duodenum (Lecco's theory). Persistence and enlargement of the left ventral bud (Baldwin's theory). Hypertrophy and fusion of the ventral and dorsal buds before rotation of the gut, resulting in complete encirclement of the duodenum. Presentation Symptoms bowel obstruction in a newborn see Bowel obstruction topic