PURPOSE: The purpose of this study is to assess the utility of PTBD spiral CT cholangiography, after infusion of contrast media through a PTBD tube, for evaluation of a biliary lesion after emergency PTBD due to severe jaundice. MATERIALS AND METHODS: Forty patients with emergency PTBD due to extrahepatic biliary obstruction were transferred to our clinic and prospectively studied. The causes of obstruction were 17 extrahepatic cholangiocarcinomas (including three Klatskin's tumors), seven pancreatic head carcinomas, six calculous diseases of the common bile duct, six periampullary lesions, two ampulla of Vater carcinomas, one gall bladder carcinoma with invasion of the common hepatic duct, and one cholangitis. Diagnosis was on the basis of pathologic, radiologic, and clinical findings. Pre-contrast CT scanning was performed. After the infusion of contrast media (iothalamate : normal saline=1:10) through a PTBD tube, spiral CT scans were obtained. After IV infusion of contrast media (Ultravist, 100cc), early- and delayed-phase spiral CT scans were obtained at 45 and 210 seconds, respectively, with an interscan interval of 5mm. 3-D CT cholangiograms were then reconstituted. Spiral CT without infusion of contrast media through a PTBD tube and PTBD spiral CT cholangiography were performed in 14 cases. The level of extrahepatic biliary obstruction was categorized as either upper, middle, or lower third. In 21 surgically confirmed cases, we evaluated the accuracy with which the level and cause of obstruction was determined; levels and causes during surgery and by as seen on PTBD cholaniography were compared. RESULTS: The levels of obstruction diagnosed on PTBD spiral CT cholangiography and on 3-D CT cholangiography corresponded in all cases to the levels during surgery and on PTBD cholangiography [upper third (n=7), middle third (n=12), lower third (n=21)], and the level diagnosed on spiral CT without infusion of contrast media through a PTBD tube corresponded to the level during surgery in ten of 14 cases. The cause of obstruction diagnosed on PTBD spiral CT cholangiography corresponded to pathologic findings in 19 of 21 cases. In 15 cases, 3-D CT cholangiography was diagnostically helpful. CONCLUSION: PTBD spiral CT cholangiography is a useful diagnostic method for determining the level and cause of biliary obstruction.