A method of filling an aneurysm space within the abdominal aorta is disclosed. The method involves placing a prosthesis in the abdominal aorta; delivering a fillable bladder in a deflated state into the aneurysm space using a catheter; placing a filler tube in fluid communication with an inflow port of the fillable bladder. The fillable bladder comprises a bladder seal surrounding the fillable bladder and the bladder seal has a first side, a second side, a third side, and a fourth side. The first side is symmetric with the second side with respect to a first axis of the fillable bladder and the third side is symmetric with the fourth side with respect to a second axis of the fillable bladder. The first axis is perpendicular to the second axis. The method further involves filling the fillable bladder with a filling agent and removing the filler tube.