Sac perfusion may be helpful in preventing or reversing spinal cord injury after endovascular repair of thoracoabdominal aneurysms and it has been used as an adjunct to the standard physiologic measures of sustained hypertension and cerebrospinal fluid drainage. Coagulopathy as a result of endoleak after endovascular aneurysm repair has been reported, and very rare cases of treatment after repair of these endoleaks have been described. We report a 73-year-old man who had endovascular repair of a type II thoracoabdominal aneurysm with a branched stent graft. Sac reperfusion was initiated to manage postoperative paraplegia. The paraplegia partially resolved but severe hemorrhagic complications developed that were attributed to sac perfusion–related hyperfibrinolysis. Discontinuation of sac perfusion resolved the coagulopathy but resulted in paraplegia.