AIM: To evaluate the effects of extrahepatic collaterals to the liver on liver damage and patient outcome after embolotherapy for the ruptured hepatic artery pseudoaneurysm following hepatobiliary pancreatic surgery.METHODS: We reviewed 9 patients who underwent transcatheter arterial embolization (TAE) for the ruptured hepatic artery pseudoaneurysm following major hepatobiliary pancreatic surgery between June 1992 and April 206. We paid special attention to the extrahepatic arterial collaterals to the liver which may affect post-TAE liver damage and patient outcome.RESULTS: The underlying diseases were all malignancies, and the surgical procedures included hepatopancreatoduodenectomy in 2 patients, hepatic resection with removal of the bile duct in 5, and pancreaticoduodenectomy in 2. A total of 11 pseudoaneurysm developed: 4in the common hepatic artery, 4 in the proper hepatic artery, and 3 in the right hepatic artery. Successful hemostasis was accomplished with the initial TAE in all patients, except for 1. Extrahepatic arterial pathways to the liver, including the right inferior phrenic artery, the jejunal branches, and the aberrant left hepatic artery,were identified in 8 of the 9 patients after the completion of TAE. The development of collaterals depended on the extent of liver mobilization during the hepatic resection,the postoperative period, the presence or absence of an aberrant left hepatic artery, and the concomitant arterial stenosis adjacent to the pseudoaneurysm. The liver tolerated TAE without significant consequences when at least one of the collaterals from the inferior phrenic artery or the aberrant left hepatic artery was present. One patient, however, with no extrahepatic collaterals died of liver failure due to total liver necrosis 9 d after TAE.CONCLUSION: When TAE is performed on ruptured hepatic artery pseudoaneurysm, reduced collateral pathways to the liver created by the primary surgical procedure and a short postoperative interval may lead to an unfavorable outcome.