The surface of red blood cells contains markers that the immune
system can recognize—one of these markers is the Rh factor (Rh [D] antigen). A
person whose blood contains the Rh factor is Rh-positive (D); a person whose
blood does not contain the Rh factor is Rh-negative (d).
Blood type contains information about the presence (+) or absence
(–) of the Rh factor. Blood type is indicated by a letter (A, B, or O) and a
symbol (+ or –). If a person has B negative (B–) blood, for example, that
person is Rh-negative. A person with B positive blood (B+) is
Sarah Marshall, MD - Family Medicine & William Gilbert, MD - Maternal and Fetal Medicine
The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.