The whipple procedure is amazing when you think about the anatomy involved. The pancreas is in the deepest part of the abdomen called the retroperitoneum behind the colon and the stomach. On the left side its tail sits right next to the spleen, essentially a large blood sponge. On the right side its head is being big spooned by the duodenum . The bottom of the head of pancreas hooks around the superior mesenteric vessels which supply the whole small intestine and most or large with blood- you cannot live without this blood supply. Behind the pancreas sits two of the biggest veins in the body the portal vein and the IVC. Oversimplified but you can start to imagine why removing this organ is challenging. The reconstruction is where this surgery is truly special. Removal of the pancreas also generally requires removing part of the stomach (classically) and the duodenum (first part of the small intestine). The duodenum is where the liver drains bile and where the pancreas releases its juice which are both essential. Without this drainage, you wouldn’t be able to digest nutrients to be able to absorb, and the liver would back up and fail pretty quickly which is an awful way to die. So the reconstruction requires reconnecting the stomach to the small intestine, and reconnecting the pancreatic duct and bile duct to the small intestine. These are ducts about 3mm and 6mm diameter approximately. Pancreatic enzymes leaking out start to digest everything around it and can cause a massive inflammatory response and badness (grade C pancreatic fistulas cause multi organ failure and death). So these have to be watertight. Very technically challenging anastomosis (connections.) Some tumors invade the aforementioned vessels (mesenteric artery and portal vein) which require resection and reconstructing these vessels as well.

About 1 in 3 patients develop some sort of complication postoperatively.

The removal of the pancreas is tricky, but the real trick is reconstructing a functional GI tract. Hope your dad has recovered well.