Your use of this information means that you agree to the Terms of Use and Privacy Policy. Learn how we develop our content. To learn more about Healthwise, visit Healthwise. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. Skip Navigation. Top of the page. Test Overview Blood type tests are done before a person gets a blood transfusion and to check a pregnant woman's blood type.
If your red blood cells have: The A antigen. The B antigen. Neither the A nor B antigen. Both the A and B antigens. Rh test Rh blood type checks for the Rh antigen also called the Rh factor on red blood cells.
If your red blood cells: Have the Rh antigen, your blood is Rh-positive. Do not have the Rh antigen, your blood is Rh-negative. When a woman is planning to become pregnant or first becomes pregnant. Before you donate blood. Before you have surgery. Before a person donates an organ for transplantation. To show whether two people could be blood relatives. To check the identity of a person suspected of committing a crime.
How To Prepare In general, there's nothing you have to do before this test, unless your doctor tells you to. How It Is Done A health professional uses a needle to take a blood sample, usually from the arm. How It Feels When a blood sample is taken, you may feel nothing at all from the needle. Risks There is very little chance of having a problem from this test.
Results Blood type tests are done before a person gets a blood transfusion and to check a pregnant woman's blood type. Credits Current as of: June 17, Previous Section: Related Information Top of the page. These blood substitutes normally contain hemoglobin- as well as perfluorocarbon-based oxygen carriers. Figure 3. This chart summarizes the characteristics of the blood types in the ABO blood group. See the text for more on the concept of a universal donor or recipient.
Antigens are nonself molecules, usually large proteins, which provoke an immune response. In transfusion reactions, antibodies attach to antigens on the surfaces of erythrocytes and cause agglutination and hemolysis. ABO blood group antigens are designated A and B. People with type A blood have A antigens on their erythrocytes, whereas those with type B blood have B antigens.
A second group of blood antigens is the Rh group, the most important of which is Rh D. This is known as hemolytic disease of the newborn. Answer the question s below to see how well you understand the topics covered in the previous section. ABO blood group: blood-type classification based on the presence or absence of A and B glycoproteins on the erythrocyte membrane surface.
Rh blood group: blood-type classification based on the presence or absence of the antigen Rh on the erythrocyte membrane surface.
American Red Cross US. Blood types [Internet]. Skip to main content. Module 2: The Cardiovascular System: Blood. Search for:. Blood Typing Learning Objectives By the end of this section, you will be able to: Describe the two basic physiological consequences of transfusion of incompatible blood Compare and contrast ABO and Rh blood groups Identify which blood groups may be safely transfused into patients with different ABO types Discuss the pathophysiology of hemolytic disease of the newborn.
Critical Thinking Questions Following a motor vehicle accident, a patient is rushed to the emergency department with multiple traumatic injuries, causing severe bleeding. What type of blood is transfused, and why? In preparation for a scheduled surgery, a patient visits the hospital lab for a blood draw. The technician collects a blood sample and performs a test to determine its type.
To the first well she adds anti-A antibody. To the second she adds anti-B antibody. Both samples visibly agglutinate. The possible outcomes are shown below:. Both A and B alleles are dominant over O. As a result, individuals who have an AO genotype will have an A phenotype. People who are type O have OO genotypes. In other words, they inherited a recessive O allele from both parents. The A and B alleles are codominant. Therefore, if an A is inherited from one parent and a B from the other, the phenotype will be AB.
Agglutination tests will show that these individuals have the characteristics of both type A and type B blood. If you wish to explore the reason why this is true, select the Bombay Phenotype button below. ABO Blood type antigens are not only found on the surface of red cells. They are also normally secreted by some people in their body fluids, including saliva, tears, and urine. Whether someone is able to secrete them is genetically controlled. Police agencies now routinely use this so-called secretor system data to identify potential victims and criminals when blood samples are not available.
Despite the fact that the blood types of children are solely determined by inheritance from their parents, paternity in the U. Antibodies to alien antigens in the ABO group are usually present in our plasma prior to the first contact with blood of a different ABO type. This may be partly explained by the fact that these antigens are also produced by certain bacteria and possibly some plants. When we come in contact with them, our bodies may develop long-term active immunity to their antigens and subsequently to the same antigens on the surface of red blood cells.
This usually occurs in babies within the first six months following their birth. Environmental Factors. It does this through natural selection. Specific ABO blood types are thought to be linked with increased or decreased susceptibility to particular diseases.
For instance, individuals with type A blood are at a somewhat higher risk of contracting smallpox and developing cancer of the esophagus, pancreas, and stomach. People who are type O are at a higher risk for contracting cholera and plague as well as developing duodenal and peptic ulcers. Research suggests that they are also more tasty to mosquitoes.
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