Pancreatic pseudocysts. When to drain, when to wait. Acute pain in the upper abdomen in a patient recovering from pancreatitis or abdominal trauma may herald a pancreatic pseudocyst. Although small cysts resolve spontaneously, those larger than 6 cm across usually require treatment to prevent such complications as rupture into adjacent structures and infection. The authors describe operative and nonoperative treatment methods and the success reported with each. 