Fainting while getting blood drawn?

[nic0L3tt3]

I am 23 y/o in perfect health. I went yesterday with to get some testing done to find out if I am a perfect match to donate a Kidney to my mother. Part of the process is having your blood drawn. The IV Nurse took about 15 vials (she took 30 in total) and I started feeling my blood pressure drop. I told him I felt dizzy and I started to perspire. I don't remember blacking out, but I was dreaming about my dog. Then I hear 10 different voices shouting my name, and I regained consciousness. Was this simply a case of mind over matter because I was watching him take my blood? Or is there a medical explanation (Hence the term MEDICAL, means I want people to reply who know what they are talking about)?
Thanks :]

[sunscream28]

Hi - I don't really know the medical reasons behind this but I think it's pretty common to faint when you have blood drawn. Happens to me after about 2 vials so I'm impressed you lasted so long! I wouldn't worry about it if I were you.