The following points should be remembered by surgeons (Table 1). In writing about the head of the pancreas, the common bile duct, and the duodenum in 1979, the authors stated that Embryologically, anatomically and surgically these three entities form an inseparable unit. Their relations and blood supply make it impossible for the surgeon to remove completely the head of the pancreas without removing the duodenum and the distal part of the common bile duct. Here embryology and anatomy conspire to produce some of the most difficult surgery of the abdominal cavity. The only alternative procedure, the so-called 95% pancreatectomy, leaves a rim of pancreas along the medial border of the duodenum to preserve the duodenal blood supply. The authors had several conversations with Child, one of the pioneers of this procedure, whose constant message was to always be careful with the blood supply of the duodenum (personal communication, 1970). Beger et al popularized duodenum-preserving resection of the pancreatic head, emphasizing preservation of endocrine pancreatic function. They reported that ampullectomy (removal of the papilla and ampulla of Vater) carries a mortality rate of less than 0.4% and a morbidity rate of less than 10.0%. Surgeons should not ligate the superior and inferior pancreaticoduodenal arteries because such ligation may cause necrosis of the head of the pancreas and of much of the duodenum. The accessory pancreatic duct of Santorini passes under the gastrointestinal artery. For safety, surgeons should ligate the artery away from the anterior medial duodenal wall, where the papilla is located, thereby avoiding injury to or ligation of the duct. "Water under the bridge" applies not only to the relationship of the uterine artery and ureter but also to the gastroduodenal artery and the accessory pancreatic duct. In 10% of cases, the duct of Santorini is the only duct draining the pancreas, so ligation of the gastroduodenal artery with accidental inclusion of the duct is catastrophic. With the Kocher maneuver, surgeons reconstruct the primitive mesoduodenum and achieve mobilization of the duodenum, which is useful for some surgical procedures. Surgeons should not skeletonize more than 2 cm of the first part of the duodenum. If more than 2 cm of skeletonization is done, a duodenostomy using a Foley catheter may be necessary to avoid blow-up of the stump secondary to poor blood supply. Proximal duodenojejunostomy is advised for the safe management of patients with difficult duodenal stumps. Roux-en-Y choledochojejunostomy and duodenojejunostomy divert bile and food in the treatment of the complicated duodenal diverticulum. The suspensory ligament may be transected with impunity. It should be ligated before being sectioned so that bleeding from small vessels contained within can be avoided. Failure to sever the suspensory muscle completely, which is possible if the insertion is multiple, fails to relieve the symptoms of vascular compression of the duodenum (Fig. 18). Mobilization, resection, and end-to-end anastomosis of the duodenal flexure have been performed as a uniform surgical procedure, avoiding the conventional gastrojejunostomy. With a large, penetrating posterior duodenal or pyloric ulcer, surgeons should remember that The proximal duodenum shortens because of the inflammatory process (duodenal shortening) The anatomic topography of the distal common bile duct and the opening of the duct of Santorini and the ampulla of Vater is distorted Leaving the ulcer in situ is wise Careful palpation for or visualization of the location of the ampulla of Vater or common bile duct exploration with a catheter insertion into the common bile duct and the duodenum are useful procedures In most cases, the common bile duct is located to the right of the gastroduodenal artery at the posterior wall of the first part of the duodenum. (ABSTRACT TRUNCATED)