Pancreaticobiliary maljunction is a congenital malformation, in which the pancreatic and bile ducts join anatomically outside the duodenal wall, forming a markedly long common channel. This anomaly prevents normal control by the sphincter of Oddi located in the duodenal wall, allowing regurgitation of pancreatic juices into the biliary tract and possibly leading to a higher probability of pancreaticobiliary cancers.

The causes of hemosuccus pancreaticus can be grouped into diseases of the pancreas and diseases of the vascular structures around the pancreas. Diseases of the pancreas include acute and chronic pancreatitis, pancreatic cancer, pancreatic duct stones, ruptured aneurysms of the splenic artery, and pseudoaneurysms of the splenic artery and hepatic artery. Pseudoaneurysms are complications of pancreatitis where a pseudocyst is formed, with one wall abutting an artery, usually the splenic artery. Should the arterial wall rupture, the pseudoaneurysm will hemorrhage into the pancreatic duct.

Rarely the bleeding is not channeled into the bowel from the main pancreatic duct (or "duct of Wirsung"), but rather comes from the accessory pancreatic duct (or "duct of Santorini"). The former is termed "Wirsungorrhage" and the latter is termed "Santorinirrhage". Bleeding from the duct of Santorini can be caused by pancreas divisum, a possible congenital cause of pancreatitis.

Hemosuccus pancreaticus, also known as pseudohematobilia or Wirsungorrhage is a rare cause of hemorrhage in the gastrointestinal tract. It is caused by a bleeding source in the pancreas, pancreatic duct, or structures adjacent to the pancreas, such as the splenic artery, that bleed into the pancreatic duct, which is connected with the bowel at the duodenum, the first part of the small intestine. Patients with hemosuccus may develop symptoms of gastrointestinal hemorrhage, such as blood in the stools, maroon stools, or melena, which is a dark, tarry stool caused by digestion of red blood cells. They may also develop abdominal pain. It is associated with pancreatitis, pancreatic cancer and aneurysms of the splenic artery. Hemosuccus may be identified with endoscopy (esophagogastroduodenoscopy), where fresh blood may be seen from the pancreatic duct. Alternatively, angiography may be used to inject the celiac axis to determine the blood vessel that is bleeding. This may also be used to treat hemosuccus, as embolization of the end vessel may terminate the hemorrhage. However, a distal pancreatectomy—surgery to removal of the tail of the pancreas—may be required to stop the hemorrhage.