Post–endoscopic retrograde cholangiopancreatography pancreatitis: Overview and pathophysiology

Endoscopic retrograde cholangiopancreatography is a widely used therapeutic endoscopic procedure with small risk of complications. The most common and dreadful complication is post–endoscopic retrograde cholangiopancreatography pancreatitis (PEP). Concerning the definition of PEP itself and classification of its severity, there is still some ambiguity. The most commonly used definition is the one proposed in the 1991 consensus, although there are indications that the current clinical definition and the 2 new severity classifications, namely the revised Atlanta classification and the determinant-based classification are more accurate in diagnosing and classifying PEP, respectively. Pathogenesiswise, although the inflammatory cascade after trypsin activation is the same regardless of the etiology and has been studied intensively over the last few years, the data on the initial pancreatic insult in PEP are scarce. Several factors have been proposed as the first trigger to include mechanical trauma or thermal injury or both to the papilla, high hydrostatic pressure in the pancreatic duct, contrast-induced injury, and contamination of the pancreatic duct by intestinal flora. The authors׳ impression is that the onset of PEP is likely multifactorial, a combination of the aforementioned mechanisms in an already susceptible subject carrying, yet to be identified, environmental or genetic risks or both. Trypsin is not only the main digestive, but also the regulatory enzyme that activates the rest of the zymogens. Intrapancreatic activation of trypsinogen results in pancreatic autodigestion and a subsequent burst of cytokine release that may progress to either a local or a systemic inflammatory response.