IntroductionMassive bleeding may complicate the course of either acute or chronic pancreatitis. Although the latter is more frequently involved when bleeding occurs in the acute form, a poorer prognosis is to be expected. Abscess, severe inflammation, regional necrosis, and pseudocysts may cause major vessel erosion, with or without pseudoaneurysm formation, whose eventual rupture may result in massive bleeding into the gastrointestinal tract, retroperitoneum, and peritoneal cavity.AimsTo define the most important pathophysiologic mechanisms and factors that might contribute to a better understanding, better prevention, and more efficient treatment of severe hemorrhage complicating acute necrotizing pancreatitis. Awareness of high-risk conditions occurring during the natural evolution of the disease (from extensive local severe enzymatic damage to late septic sequelae), avoidance of a too early and too aggressive approach to sterile pancreatic necrosis, and providing prompt and effective treatment of local septic complications, when they occur, are crucial steps for bleeding prevention.MethodologyForty-four cases of severe bleeding following acute pancreatitis that were reported during the last decade since 1992 (including the six cases reported here) are reviewed, analyzed, and summarized.ResultsThe overall mortality rate was 34.1%. Splenic artery, portal vein, spleen, and unspecified peripancreatic vessels were the most commonly involved sources of bleeding, with associated mortality rates of 33.3%, 50.0%, 30%, and 28.5%, respectively. Massive hemorrhage was more frequently associated with severe necrosis, with a mortality rate of 37.9%.ConclusionThe increased use of diagnostic and interventional radiology, in association with prompt surgical treatment, appears to be the way to improve survival rates in cases of arterial bleeding. Venous bleeding due to lesion of major peripancreatic veins or diffuse bleeding represents a therapeutic challenge, and treatment of these conditions should be tailored to the individual case, as no general rule can be suggested. In extreme cases, open packing or salvage emergency pancreatectomy may represent the only chances for survival.