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Alicorn comments on Efficient Charity: Do Unto Others... - Less Wrong

130 Post author: Yvain 24 December 2010 09:26PM

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Comment author: Alicorn 25 December 2010 07:09:59PM 4 points [-]

unless you've been pregnant a couple times - in that case, consider stopping

I've never been pregnant, but what is it about multiple pregnancies that renders the blood non-preferred?

Comment author: Eliezer_Yudkowsky 25 December 2010 07:18:25PM 3 points [-]

Obvious guess: Your blood then contains antibodies to the blood type of your babies.

Comment author: Marius 25 December 2010 07:25:27PM 2 points [-]

Essentially this. The A/B/O blood groups represent the most relevant antigens in human blood. There are a host of others (Rh, Duffy, Kell, etc.) which typically create only minor problems in a transfusion and which can be ignored in an emergency. But a person who has been exposed to allogeneic blood via multiple transfusions or pregnancies becomes more likely to develop antibodies to some of these antigens. The donor's antibodies or white cells can react to the person being transfused, causing lung damage.

Comment author: wedrifid 25 December 2010 08:48:28PM *  3 points [-]

There are a host of others (Rh, Duffy, Kell, etc.) which typically create only minor problems in a transfusion and which can be ignored in an emergency.

In the case of the Rhesus factor it should be noted that it is minor once and then only minor for males. Being thereafter unable to safely give birth to healthy Rh+ children is definitely not a minor consequence even if it is better than 'probably going to die today'. (Unless, I suppose, you happen to some Rh+ antiserum lying around but no Rh- blood, which will usually avoid the future difficulties.)

Comment author: Marius 25 December 2010 10:34:27PM 6 points [-]

I use "minor" differently than you do, to mean "unlikely to cause death". Obviously cross-matched blood is always preferable for a variety of reasons (including possible infertility, in the case of young females).

I would avoid RhoGam in the case of a patient who needs a RBC transfusion, incidentally. It would be unlikely to be safe or effective.

Comment author: shokwave 26 December 2010 09:50:13AM *  4 points [-]

I use "minor" differently than you do, to mean "unlikely to cause death".

I would like to express that my approval of this phrase extends beyond the capacity of upvoting and into the capacity of a comment expressing approval.

Comment author: wedrifid 26 December 2010 10:04:43AM *  1 point [-]

I use "minor" differently than you do, to mean "unlikely to cause death".

And having both your arms removed is "Just a flesh wound!".