Dynamic CT scanning of pancreatic duct after secretin provocation in pancreas divisum. Variations in pancreatic duct diameter at CT scanning and serum pancreatic amylase response following secretin administration were studied in 29 patients with pancreas divisum and unexplained upper abdominal pain. Eleven healthy individuals were used as controls. At endoscopic retrograde pancreatography (ERP) six patients had signs of marked and six moderate pancreatitis, whereas there were no pancreatitis changes in 17 of the patients. At CT scanning patients with marked pancreatitis (ERP) had significantly increased pancreatic duct diameter as compared to patients without signs of pancreatitis. The duct was visualized in 52% of all patients before and 71% after secretin stimulation the corresponding figures for healthy controls, being 18% both before and after secretin. In patients without signs of pancreatitis, it was demonstrated in 5/17 (29%) before and 11/17 (65%) after secretin, whereas it was seen in 10/12 (83%) pancreatitis patients both before and after the hormonal provocation. In five of the nonpancreatitis patients in whom the duct was measurable before and at all study intervals (10, 20, and 50 min) after secretin, there was a significant duct dilation response both at 10 min and when comparing the maximal duct diameter after secretin to the initial values. In contrast secretin did not affect the duct caliber in pancreatitis patients. Serum pancreatic amylase increased significantly after secretin administration to healthy controls and nonpancreatitis patients but was uninfluenced in the marked and moderate pancreatitis groups, respectively. However, when all pancreatitis patients were grouped together, the amylase levels were significantly elevated by secretin. In conclusion, secretin provocation caused duct dilation at CT scanning in pancreas divisum patients without signs of pancreatitis at ERP. 