# More details about blood type - it's really a 43 bit binary number, right? **URL:** \ **Category:** Factual Questions\ **Created:** [October 20, 2022, 10:44am UTC](https://boards.straightdope.com/t/more-details-about-blood-type-its-really-a-43-bit-binary-number-right/973538 "2022-10-20T10:44:36Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [October 20, 2022, 10:44am UTC](https://boards.straightdope.com/t/more-details-about-blood-type-its-really-a-43-bit-binary-number-right/973538/1 "2022-10-20T10:44:36Z")
Questions inspired by the thread about “if there is no right blood type…”, I’m just trying to understand blood type here. It seems saying my type is “A” or “A+” (both true) is incomplete, but just a kind of prioritized approximation. A more complete description would answer 43 separate and unrelated yes/no questions about whether you had each of 43 different antigens on your red blood cell walls, all of which are inherited and usually life long. That is, your blood type is a 43 bit binary number. I guess this assumes all the antigens have been discovered. So, do you have: A? B? Rh? Kell? Duffy? Kidd? and on and on. It also sounds like A and B are very big deals because somebody without A has a very bad reaction to blood containing A, and likewise without B to B. Maybe these are the only ones with such strong reactions? Moreover, it sounds like Rh can be a big deal in the case of pregnant women, but not for anybody else, so for most people it can be ignored. The remaining 40 are, perhaps, minor enough issues they can be safely ignored? Or perhaps they only matter in some special circumstances? ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [October 20, 2022, 5:15pm UTC](https://boards.straightdope.com/t/more-details-about-blood-type-its-really-a-43-bit-binary-number-right/973538/2 "2022-10-20T17:15:20Z")
1. > **[Scientists Have Discovered a New Set of Blood Groups](https://www.wired.com/story/new-blood-types/)** > > The ‘Er’ grouping could help doctors identify and treat some rare cases of blood incompatibility, including between pregnant mothers and fetuses. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [October 20, 2022, 5:48pm UTC](https://boards.straightdope.com/t/more-details-about-blood-type-its-really-a-43-bit-binary-number-right/973538/3 "2022-10-20T17:48:57Z")
See? See??? ---
**Author:** ![aruvqan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aruvqan/32/2891_2.png) [@aruvqan](https://boards.straightdope.com/u/aruvqan)\ **Post date:** [October 21, 2022, 12:55am UTC](https://boards.straightdope.com/t/more-details-about-blood-type-its-really-a-43-bit-binary-number-right/973538/4 "2022-10-21T00:55:01Z")
> [@Napier](#): > > Moreover, it sounds like Rh can be a big deal in the case of pregnant women, but not for anybody else, so for most people it can be ignored. Um … … … AB neg here, if you give me anything positive, really bad things tend to happen. mrAru is O neg, and definitely anything other than O neg really bad things happen. ---
**Author:** ![Buck\_Godot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/buck_godot/32/6573_2.png) [@Buck\_Godot](https://boards.straightdope.com/u/Buck_Godot)\ **Post date:** [October 21, 2022, 8:09pm UTC](https://boards.straightdope.com/t/more-details-about-blood-type-its-really-a-43-bit-binary-number-right/973538/5 "2022-10-21T20:09:05Z")
> [@Napier](#): > > Moreover, it sounds like Rh can be a big deal in the case of pregnant women, but not for anybody else, so for most people it can be ignored. From [here](https://www.utmb.edu/bloodbank/component-therapy/emergency-red-blood-cells-usage). > An Rh- individual may make anti-D only if exposed to the D-antigen via transfusion with Rh+ blood or platelets, or if pregnant with an Rh+ fetus. The probability of forming anti-D after transfusion of Rh+ RBCs is about one-third. Note, however, that this immunologic response requires approximately 3 to 4 months to develop and the patient is NOT at immediate risk of hemolysis. Individuals who have formed anti-D must receive only Rh- RBCs If I’m reading this correctly it sounds like giving Rh+ blood to a Rh- person might be OK if that person hasn’t been previously exposed to the Rh protein, either through pregnancy or a previous infusion. But if they had been exposed things can get bad. So you’re allowed one free mismatch of forbidden blood but the next will kill you. For that reason no physician would willingly risk such a transfusion unless it was an absolute emergency. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [October 21, 2022, 8:15pm UTC](https://boards.straightdope.com/t/more-details-about-blood-type-its-really-a-43-bit-binary-number-right/973538/6 "2022-10-21T20:15:44Z")
If you want the deep dive - > **[Blood groups systems](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4260296/#!po=32.7586)** > > International Society of Blood Transfusion has recently recognized 33 blood group systems. Apart from ABO and Rhesus system, many other types of antigens have been noticed on the red cell membranes. Blood grouping and cross-matching is one of the few... For the questions asked this seems the money quote: > [@](#): > > ABO-Rh typing alone results in a 99.8% chance of a compatible transfusion. Antibody screening increases this safety margin up to 99.94%, and an additional cross-match further increases the compatibility to 99.95%. In absence of cross-matching, there is a possibility of missing the antigens on donor cells, but in clinical practice, they are of less importance. Hence, “screening and typing” alone should be carried out. Other methods include …