Olivia asks Cassandra what exsanguinate means ("bleed to death.") In "Law & Order: Special Victims Unit" Serendipity (2003), three seasons earlier, Dr. Melinda Warner used the same term, and Olivia gave the definition.
In the video of Riley Cuskey's death there is not nearly enough blood spilled to cause a healthy person to die. If the femoral artery is severed blood flows out as if from a hose. Death is very quick, a few minutes at most.