Assessment of the biliary tract after liver transplantation: T tube cholangiography or IODIDA scanning. Biliary tract obstruction or anastomotic leakage are common problems following liver transplantation. In a sequential study, 31 patients with a liver transplant were investigated by 99mTc-IODIDA (IODIDA) scanning and T tube cholangiography (TTC) and the results were compared with clinical outcome. Seven patients had an extrahepatic biliary obstruction and one patient had a biliary leak. In the detection of biliary complications TTC and IODIDA scanning were similar in terms of sensitivity (63 per cent for both) but TTC had a better specificity (79 per cent versus 60 per cent) and accuracy (74 per cent versus 60 per cent) than IODIDA scanning. When liver function was taken into account, the diagnostic efficacy of both tests in patients with bilirubin levels of less than 200 mumol/l was similar. With levels greater than 200 mumol/l there was a greater number of false positive results with IODIDA scanning (12 per cent versus 54 per cent). The only significant biliary leak was clearly detected by TTC but not IODIDA scanning. TTC remains the more effective way of evaluating the biliary tract after transplantation. IODIDA scanning has limited value when bilirubin levels are elevated, but may provide additional information about blood supply, hepatocyte function and intrahepatic cholestasis. 