I gave blood again today. This time, they asked if I'd be willing to try something new: apheresis. In normal blood donation, they collect full blood: plasma, red and white cells, and platelets. The Red Cross primarily only uses the red blood cells, and usually discards the rest. With apheresis, the blood is drawn, the red blood cells extracted, and the remainder of the blood (along with an anticoagulant) is reinjected into the body. I was told that men are better suited to the process than women, though no one really explained that part to me very well.
A single needle is used for the apheresis I did today. The first part of the process - the blood letting -- is the same as in normal blood donations. The part where they return the blood is unique. The plasma is cold, and I did feel the coldness in my veins, which was weird. I also felt an itch inside, but the lab technician didn't really believe me. Apheresis takes longer than a traditional donation, with the draw and inject process repeated four times.
The upshot to apheresis is that the Red Cross can get twice the quantity of red blood cells per donor, without having to waste all the plasma or platelets. I am unable to donate again for 112 days now, as opposed to the 56 day wait after a traditional donation.
All in all, the process wasn't terribly different from any other blood donation I've ever made, except that it took a little longer.