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Results 1 - 2 of 2 for Blood types a b ab o
  1. Blood (National Library of Medicine)  
    ... but others live much longer. There are four blood types: A, B, AB, or O. Also, blood is either Rh-positive or Rh-negative. So if you have type A blood, it's either A positive or A ...
    https://medlineplus.gov/blood.html - Health Topics
  2. Rh Incompatibility (National Library of Medicine)  
    There are four major blood types: A, B, O, and AB. The types are based on substances on the surface of the blood cells. Another blood type is called Rh. Rh ...
    https://medlineplus.gov/rhincompatibility.html - Health Topics