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Rh factor

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 Rh-positive.

Author Jeannette Curtis
Author Caroline Rea, RN, BS, MS
Editor Kathleen M. Ariss, MS
Editor Susan Van Houten, RN, BSN, MBA
Associate Editor Tracy Landauer
Associate Editor Pat Truman
Primary Medical Reviewer Patrice Burgess, MD
- Family Medicine
Primary Medical Reviewer Adam Husney, MD
- Family Medicine
Primary Medical Reviewer Kathleen Romito, MD
- Family Medicine
Last Updated May 25, 2007

WebMD Medical Reference from Healthwise

Last Updated: May 25, 2007
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