ive done it and it was the most horrible experience of my life!!! i will NEVER do it again!!! the people seemed like ameturs. they had to chase my vein almost 4 times. (which means they dug it in my arm, ripped it out and repeated that 4 times!) then once it was over they dug it up in my arm so much that the needle got stuck! so what did they do?!? the attendent grabbed the tube and with one hard jerk, ripped it out of my arm! it hurt me soo much, i was in pain and was bruised for almost a week.