At a Glance

Why Get Tested?

To detect antibodies directed against ruby blood prison cell antigens

When To Get Tested?

When preparing for a claret transfusion; during pregnancy and at delivery

Sample Required?

A blood sample drawn from a vein in your arm

Test Grooming Needed?

None

What is beingness tested?

The RBC antibody screen looks for circulating antibodies in the claret directed against red blood cells (RBCs). The primary reason that a person may have RBC antibodies circulating in the blood is because the person has been exposed, through blood transfusion or through pregnancy, to RBCs other than his or her own (foreign RBCs). These antibodies have the potential to cause harm if a person is transfused with reddish blood cells that the antibodies may target or if a pregnant woman has antibodies that target the ruby-red cells of her developing baby.

RBCs usually have structures on their surface chosen antigens. People take their own private set of antigens on their RBCs, determined past inheritance from their parents. The major antigens or surface identifiers on human RBCs are the O, A, and B antigens, and a person'due south blood is grouped into an A, B, AB, or O blood blazon according to the presence or absence of these antigens.

Another important surface antigen is Rh cistron, also called D antigen. If it is present on a person's red blood cells, that person's blood type is Rh+ (positive); if it is absent, the blood is type Rh- (negative). (For more on these antigens, see the commodity on Blood Typing). In improver, there are many other types of RBC antigens that make upwardly lesser-known blood groups, such as Kell, Lewis, and Kidd blood groups.

There are a few reasons why someone may produce antibodies confronting RBC antigens.

  • Following blood transfusions: Antibodies directed against A and B red cell antigens are naturally-occurring; we produce them without having to exist exposed to the antigens. Before receiving a blood transfusion, a person's ABO group and Rh type are matched with that of donor claret to prevent a serious transfusion reaction from occurring. That is, the donor's blood must be uniform with the recipient's then that antibodies exercise non react with and destroy donor blood cells.If someone receives a blood transfusion, the person's body may likewise recognize other RBC antigens from other blood groups (such as Kell or Kidd) that the person does not accept as strange. The recipient may produce antibodies to attack these foreign antigens. People who take many transfusions make antibodies to RBCs because they are exposed to foreign RBC antigens with each transfusion.
  • During pregnancy, with blood blazon incompatibility between mother and baby: A baby may inherit antigens from the male parent that are not on the female parent's RBCs. The mother may be exposed during pregnancy or at delivery to the strange antigens on her infant's RBCs when some of the baby's cells enter the mother's circulation as the placenta separates. The mother may brainstorm to produce antibodies against these strange RBC antigens. This can cause hemolytic disease of the newborn, usually not affecting the first baby but affecting subsequent children when the mother's antibodies cross the placenta, adhere to the baby's RBCs, and hemolyze them. An RBC antibody screen tin can aid determine if the mother has produced RBC antibodies outside of the ABO blood group.

The first time a person is exposed to a foreign RBC antigen, by transfusion or pregnancy, the person may brainstorm to produce antibodies merely his or her cells do not unremarkably have the time during the first exposure to make plenty antibodies to actually destroy the foreign RBCs. When the next transfusion or pregnancy occurs, the immune response may exist strong enough for plenty antibodies to exist produced, attach to, and interruption apart (hemolyze) the transfused RBCs or the baby's RBCs. Antibodies to the ABO antigens are naturally-occurring and so do not crave exposure to foreign RBCs.

Common Questions

How is it used?

An RBC antibody screen is used to screen an private'southward blood for antibodies directed confronting ruby-red blood cell (RBC) antigens other than the A and B antigens. It is performed every bit part of a "type and screen" whenever a blood transfusion is anticipated or as part of prenatal testing of significant women.

The principal reason that a person may have RBC antibodies circulating in the blood is because the person has been exposed, through claret transfusion or through pregnancy, to RBCs other than his or her own (strange RBCs). These antibodies have the potential to cause harm if a person is transfused with red blood cells that the antibodies may target or if a pregnant woman has antibodies that target the red cells of her developing babe.

If an antibody is detected, then an antibody identification test must be washed to decide which antibodies are present. During a crossmatch, a variation of the RBC antibody screen is performed if clinically significant antibodies are present. In the case of blood transfusions, RBC antibodies must exist taken into account and donor claret must be plant that does not contain the antigen(due south) to which the person has produced antibodies.

If someone has an immediate or delayed reaction to a blood transfusion, a wellness practitioner will club a direct antiglobulin test (DAT) to aid investigate the cause of the reaction. (The DAT detects RBC antibodies attached to red blood cells.) An RBC antibody screen volition be performed to see if the affected person has developed whatever new antibodies if the DAT is positive.

During pregnancy, the RBC antibody screen is used to screen for antibodies in the blood of the female parent that might cantankerous the placenta and attack the infant's carmine cells, causing hemolytic disease of the newborn (HDN). The nearly serious crusade is an antibiotic produced in response to the RBC antigen called the "D antigen" in the Rh blood group system.

A person is considered to exist Rh-positive if the D antigen is present on the person's RBCs and Rh-negative if the D antigen is not nowadays. An Rh-negative mother may develop an antibody when she is exposed to blood cells from an Rh-positive fetus. To prevent this, an Rh-negative mother should have an RBC antibody screen performed early in her pregnancy, at 28 weeks, and once again at the time of delivery. If at that place are no Rh antibodies nowadays at 28 weeks, then the woman is given an injection of Rh immune globulin (RhIg) to clear any Rh-positive fetal RBCs that may exist nowadays in her bloodstream to prevent the production of Rh antibodies by the mother.

At nascence, the baby'southward Rh condition is adamant. If the baby is Rh-negative, then the mother does non require some other RhIg injection; if the babe is Rh-positive and the mother'southward antibody status is negative for anti-D, the mother is given additional RhIG.

This exam also may exist used to aid diagnose autoimmune-related hemolytic anemia in conjunction with a DAT. This condition may be caused when a person produces antibodies confronting his or her own RBC antigens. This can happen with some autoimmune disorders, such as lupus, with diseases such equally lymphoma or chronic lymphocytic leukemia, and with infections such as mycoplasma pneumonia and mononucleosis. It can also occur in some people with the use of certain medications, such equally penicillin.

When is it ordered?

  • An RBC antibody screen is performed prior to whatsoever predictable claret transfusion.
  • An RBC antibody screen is performed early in pregnancy as function of every adult female'south pregnancy workup. In Rh-negative women, it is also done at 28 weeks, prior to giving an injection of Rh immune globulin (RhIg), and after delivery if the babe is adamant to exist Rh-positive. In negative pregnant women with known antibodies, the RBC antibody screen is sometimes ordered as a monitoring tool to roughly track the amount of antibiotic present.

What does the test result mean?

Transfusion: If an RBC antibody screen is positive, and so one or more RBC antibodies are nowadays. Some of these antibodies will exist more significant than others. When an RBC antibody screen is used to screen prior to a blood transfusion, a positive exam indicates the need for an antibiotic identification test to identify the antibodies that are nowadays. In one case the antibody has been identified, donor claret must be institute that does not contain the corresponding antigen(s) and so that the antibiotic will non react with and destroy donor RBC antigens following a blood transfusion.

Pregnancy: If an Rh-negative female parent has a negative RBC antibiotic screen, and then an Rh immune globulin injection is given inside 72 hours to prevent antibody product. If she has a positive test, then the antibiotic or antibodies present must be identified. If an antibody to the D antigen has been actively formed by the female parent, and then the RhIg injection is not useful. If she has a different antibody, and so the RhIg injection can still exist given to prevent her from producing antibodies to the D antigen.

Is there anything else I should know?

A circulating RBC antibiotic, once present, volition never truly become away but may drop to undetectable levels. If the person is exposed to the antigen again, production volition kick quickly into gear and attack the RBCs so the antibody will exist honored (treated as though information technology is present) even when not detectable.

Each blood transfusion that a person has exposes that person to the combination of antigens on the donor's RBCs. Whenever the transfused RBCs contain antigens foreign to the recipient's RBCs, there is the potential to produce an antibody. If someone has many blood transfusions over a period of fourth dimension, that person may produce antibodies against many dissimilar antigens. This can brand finding compatible blood increasingly difficult.

What happened earlier the RhIg (Rh immune globulin) injection was adult?

Prior to development of the injection, Rh-negative mothers would often become sensitized from the blood of their first Rh-positive baby and brainstorm developing anti-Rh antibodies. Any subsequent Rh-positive babies would have some caste of Rh illness, due to the mother'due south anti-Rh antibodies attacking the baby's RBCs. Miscarriages and stillborn babies were relatively mutual, and those babies who were born often needed firsthand blood transfusions to survive. The immune globulin injection has largely prevented these complications, although a small-scale percent of women do still develop Rh antibodies.

I'm claret type O. Do I take a take chances of having a infant with ABO hemolytic disease of the newborn?

Yes. Hemolytic disease of the newborn may occur when in that location is an ABO incompatibility between mother and infant, particularly with mothers who are blood group O. However, the RBC antibody screen is not useful in this situation because our bodies naturally produce antibodies confronting the A and B antigens we practice not have on our red blood cells. A mother who is blood type A will naturally take antibodies directed against the B surface antigens on reddish blood cells, and a mother who is type B will have anti-A antibodies, and so on. Generally, this is a mild form that is easily treatable.

Tin I get antibodies from donating claret?

No, you will not exist exposed to anyone else'southward blood while altruistic.

Related Content

View Sources

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