Okay, I need help researching something for my sci-fi story. It's about blood transfusion. Basically, Captain Helen Chert discovers in the sick bay of her ship a child that's loosing a lot of blood. Without hesitation, Helen suggests for the doctor (Doctor Jackie) to hook them both to a blood transfusion machine. As a person with absolutely 0 knowledge in the medical field...how does that work? What blood type would Helen have to be to safely give blood? Type A or Type O? What's Type AB? What does the -/+ mean? Also, wouldn't there have to be some kind of procedure, as in Dr. Jackie would have to test Helen's blood to make sure it's OK to give it to the child? What about parental consent? Would there have to be some filling out of forms or something?