Figure 2b. Renal involvement by ERCP-induced pancreatitis in a 75-year-old woman. ERCP was performed for a dilated common bile duct, and the duct was "swept" for stones. After the procedure, the patient had clinically evident pancreatitis, which was also demonstrated at multiple CT studies. She developed a perinephric fluid collection, which showed no evidence of infection at fine-needle aspiration. The collection was not drained and persisted for several weeks. CT was performed with intravenous contrast material 28 days after ERCP. (a) CT scan shows stranding of the fat (arrow) adjacent to the head of the pancreas and the duodenum. A heterogeneous fluid collection is present in the perirenal space (*). (b) CT scan obtained inferior to a shows the fluid collection displacing the intestine and abutting the psoas muscle (arrow).