Human blood groups are of 4 types with negative and positive of each types (Wikipedia). But according to this forum thread there are some other types too:


I'm going to make software for blood donation, where I need to put a dropdown list of actual blood types. I had intended to use:

[ Select Blood Group V ]
[ O Negative           ]
[ O Positive           ]
[ A Negative           ]
[ A Positive           ]
[ B Negative           ]
[ B Positive           ]
[ AB Negative          ]
[ AB Positive          ]

But now I am uncertain whether this is appropriate. What is the most suitable list of blood types for donors?

  • 2
    $\begingroup$ I've edited your question, mainly because you started it with "We all know...". This is unnecessary and is often either offensive (you have no idea what I know, and you are suggesting I am ignorant if I am not aware of your assertion) or a ploy (presenting something dubious as a fact). If you really must, use "It is well known...". I've condensed the rest, which was too verbose. Also note that in English "software" is uncountable, it never has an indefinite article — either "software" (in this case) or "the software" (referring to a specific program), but never "a software". $\endgroup$
    – David
    Commented Aug 20, 2016 at 13:46
  • $\begingroup$ @David thanks for the edit and the enlightenment. You are always welcome. $\endgroup$ Commented Aug 21, 2016 at 5:00

2 Answers 2


As far as I am aware it is the RhD and ABO blood groups that matter with blood donation - though you may wish to contact a blood donation organisation for more specific information on how they handle & categorise the blood.

But using just RhD and ABO gives 8 combinations, positive and negative of A, B, AB, and O. You can find out more about the blood groups, blood donation, and the characteristics of blood groups here.

The subgroups you allude to are due to differences in the number of the antigens on the surface of the blood cell, for example the A1 group have ~1,000,000 A antigens per cell whereas A2 variants have ~250,000. The A group has ~20 subgroups, the vast majority of people are A1 (~80%) or A2 (~20%), and the other groups make up less than 1% of the population.

These two subgroups are interchangeable as far as transfusion is concerned, but complications can sometimes arise in rare cases when typing the blood.


If the blood donor is filling out the info, I recommend you have one dropdown that offers: A, B, O, AB, don't know.... And a second dropdown that offers Rh +, Rh -, don't know. And be aware that the average person is not likely to correctly know their blood type.

Actual laboratory blood typing checks for a large number of possible differences between blood cells beyond just ABO types. The clinician or technician will not use anything as simple as either your drop-down OR the slightly more complex drop-down in the referenced forum post.

If you still want to know more about "what the actual blood types are," recognize that there are LOTS of blood types, including the MNS system, the Kell system, and the Lewis system: http://en.wikipedia.org/wiki/Blood_typing

  • $\begingroup$ Thanks. And, And be aware that the average person is not likely to correctly know their blood type. - kudos for the point. :) $\endgroup$ Commented May 9, 2014 at 19:32
  • $\begingroup$ don't forget AB blood. :) $\endgroup$
    – user560
    Commented May 9, 2014 at 20:09
  • $\begingroup$ Gah. Yes. Corrected. $\endgroup$
    – Adrienne
    Commented May 9, 2014 at 20:20
  • $\begingroup$ I would have assumed that someone performing the blood test is typing in the information. I doubt anyone is relying on self-reported information for blood transfusion. $\endgroup$ Commented May 9, 2014 at 20:40
  • $\begingroup$ Well, that's the thing. If it's the clinician, they need to enter a LOT more information about blood type than just ABO and Rh. And if if the user is the general public, they aren't likely to be correct. So I'm not seeing how this will be very helpful software. Unless it's a dating site. Or one of those sites that gives you an ideal diet based on your blood type. $\endgroup$
    – Adrienne
    Commented May 9, 2014 at 21:03

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