A vascular occlusion device for occluding a body cavity includes an elongate member with a first lumen and a second lumen. An inflatable balloon is disposed about a distal end of the elongate member, and is inflated with inflating fluid introduced into the interior of the balloon by way of the first lumen. The device also includes a pressure regulation system that determines the pressure of embolization material being injected from the second lumen into the body cavity to occlude the body cavity.