Acute pancreatitis and its complications. Computed tomography and sonography.

Acute pancreatitis is a clinical diagnosis. In most patients with uncomplicated acute pancreatitis, there is no need for radiologic confirmation or work-up. However, in some patients, the diagnosis may be in doubt, or associated abnormalities or complications of acute pancreatitis may be suspected by the patient's protracted course or severity of disease. In these patients, radiology can be extremely helpful. CT is the best single radiologic imaging modality to evaluate these patients. With modern scanners, there are no failures, and CT provides a complete view of the pancreas and peripancreatic tissues, despite overlying bowel gas or other anatomic features that may limit the sonographic evaluation. Sonography may be helpful in evaluating possible biliary complications of acute pancreatitis, in evaluating thin patients with a good sonic window to the pancreas, or in evaluating patients who have a clearly defined complication such as a large pseudocyst. Sonography is also helpful for serial studies following the size of the fluid collection. The complications of pancreatitis include fluid collections and pseudocysts, which may become infected or develop bleeding within them, vascular complications including occlusion of the splenic vein with secondary development of varices, pancreatic ascites, and pancreatic abscess. While these complications can be evaluated by various radiologic methods, they are most effectively evaluated by CT. However, for some cases in which the cause of a cystic mass is in doubt or for cases of suspected pancreatic abscess, radiologic studies may be unable to provide a definitive diagnosis. In these cases, percutaneous needle aspiration will assist in the diagnosis.