I have been a regular blood donor for almost three years. I'm what they call a "universal donor" (Type O, Rh negative or "O Neg" like they say on ER), and my blood can be used in an emergency to help anyone. Canadian Blood Services always calls me about every 7 weeks to remind me that I'll be eligible to donate again on such-and-such date. Donating blood is not a harmful procedure for a healthy individual to do.
And yes, if I was critically injured or ill and needed blood to save my life, I would accept blood. If my children or husband were sick or injured and needed blood, I would authorize a transfusion without hesitation.
If I was facing elective surgery, I would opt for storing my own blood in advance of the surgery.
When I was a JW, I was under the misguided impression that doctors and hospital staff were perched like vultures, waiting for any JW to come in and ready to force blood on us by whatever means possible. My misconception disappeared when I became a nurse and realized just how valuable blood is, and how doctors can only order blood transfusions when very strict criteria is met. JWs have the notion that there's so much blood in the system that hospitals can just load you up and not miss a beat. They tend to think that because blood is "donated" that it's inexpensive to treat someone with it. Nothing could be further from the truth. While donors are not compensated for donating their blood in Canada (which prevents people from donating for the money when they really shouldn't be donating at all), it costs about $300 to process a single unit of blood. When a patient is sick enough to need a blood transfusion (haemoglobin level less than 70 mg/L is the standard we use), doctors order a minimum of two units in order to bring the haemoglobin level back into an acceptable range. There are so many checks and double checks, so many screening procedures for HIV, Hepatitis, malaria, and now CJV (Mad Cow disease), just to name a few, that I'm confident that the blood supply in Canada is safer now than it has ever been. In the five years that I've been a nurse, I've administered probably three dozen transfusions on my ward (maternal newborn care) and during my training in an outpatient cancer treatment centre, and I have not seen even a minor case of what is known as "transfusion reaction", not even a minor increase in a patient's temperature.
Love, Scully