The Significance of Rh Typing In the Medical Setting

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What Is RH Typing

RH typing is a blood typing test performed to determine whether or not a protein, commonly referred to as Rhesus factor (Rh), is present on the surface of blood cells. While the majority of the population is Rh positive, special precautions sometimes need to be taken for those who aren’t.

Although being Rh negative isn’t a cause for concern in the healthy individual, it can be pertinent to know this information in certain situations. The significance of Rh typing cannot be stressed enough for pregnant women or those who might be in need of a transfusion of blood or blood products.

How the Test Is Performed

This is a simple blood test that generally requires no special preparation and can be performed in a variety of healthcare settings. However, someone undergoing the test should consult with his or her physician prior to testing. At times, the test may be ordered in combination with other testing that may require that special procedures be followed.

During the test a sample of blood is obtained from a vein, typically in the arm. The sample is then analyzed in a laboratory. Typically, the sample does not need to be sent off but this will depend on the physician, facility in which the test was performed, and whether or not anything else is being screened for.

Why a Physician May Order This Test

Rh blood typing may be ordered for a variety of reasons. However, the most common reasons for ordering such a test may be when the patient is receiving and/or donating blood products or when a woman is pregnant. For blood donoros or recipients, this measure helps prevent complications that might prove fatal.

In the case of pregnancy, the immune system of an Rh - mother who is carrying an Rh+ fetus can sometimes develop antibodies against the child’s red blood cells. This results in hemolytic disease of the newborn, a disease characterized by the bursting of the child’s red blood cells.

The Significance of Rh Typing Results

Once the Rh type has been discovered, the physician can use this information to successfully prevent life threatening reactions that may occur if the individual has been exposed to another Rh factor. This is crucial because the Rh negative individual will typically not have any problems upon the initial exposure to Rh positive blood products. Instead, the antibodies will be created after this contact that can make future exposure deadly for the patient. Pregnant women who are tested and found to be Rh negative can be treated with immune globulins to prevent adverse affects during and after the pregnancy.


Blood Typing. Lab Tests Online. Modified 10, June 2010. Viewed 14, June 2010. 2001-2010. American Association of Clinical Chemistry.

Rh Factor Blood Test. Mayo Clinic. 27, April 2010. Viewed 14, June 2010. 1998-2010. Mayo Foundation for Medical Education and Research.