Blood Type Test

ABO Blood Typing, Rh Blood Typing

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Having a recent X-ray test with contrast material.
• Taking methyldopa, levodopa, or some antibiotics, such as cephalexin. These medicines may cause a false Rh-positive result.
• Having a blood transfusion in the 3 months before the blood type test.
• Having cancer or leukemia.
• Having a bone marrow transplant.

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Author:	Maria G. Essig, MS, ELS	Last Updated: June 12, 2008
Medical Review:	Anne C. Poinier, MD - Internal Medicine W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
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