Acute pancreatitis is a clinical syndrome characterized by abdominal and back pain that may be associated with nausea, vomiting, and fever. Blood tests will reveal increased levels of pancreatic enzymes, and imaging studies (CT or MRI) will show inflammation in the pancreas and there may be fluid around the pancreas. These peripancreatic fluid collections may eventually become a pseudocyst. Pancreatic pseudocysts are pockets of fluid that are lined with either inflammatory or scar tissue. The vast majority of acute pancreatitis in the United States is caused by gallstones or alcohol. However, there are other less common causes such as medications (eg. thiazide diuretics), very elevated serum triglycerides, and rare genetic mutations.
Many pseudocysts will heal without treatment. Large and symptomatic pseudocysts however, may need to be drained. Internal drainage is the preferred method. In this procedure, once the pseuodcyst has matured (6 weeks following the onset of acute pancreatitis), it can be connected to the stomach or to a loop of bowel. This connection often can be achieved endoscopically (endoscopic cystgastrostomy or endoscopic cystenterostomy). When this is not feasible, the procedure can be performed surgically. External drainage is avoided if possible because it creates a connection between the pancreas and the skin that takes many months to heal. External drainage is reserved for patients that are too sick to undergo endoscopic or surgical drainage, often from an infection or worsening pancreatitis.