Blood Typing and Crossmatching

Blood Typing and Crossmatching

Blood Typing and Crossmatching

What are blood typing and crossmatching?

If you need a blood transfusion or transplant, your doctor can use blood typing and be crossmatching to learn if your blood is compatible with donor blood or organs.

Blood typing reveals what type of blood you have. This depends on the presence of certain antigens on your red blood cells (RBCs). Antigens are proteins that trigger your immune system to produce antibodies. There are four main types of blood:

  • type A blood, which contains type-A antigens
  • type B blood, which contains type-B antigens
  • type AB blood, which contains type-A and type-B antigens
  • type O blood, which contains neither type-A nor type-B antigens

Your blood will also be classified as Rh positive (+) or Rh negative (-), based on the presence or absence of a particular protein on your RBCs, known as rhesus factor.

Crossmatching is a test used to check for harmful interactions between your blood and specific donor blood or organs. It can help your doctor predict how your body will react to those donor materials.

What are these tests used for?

Your doctor uses blood typing and crossmatching to learn if donor blood or organs are compatible with your blood. Incompatible donor blood or organs can cause harmful interactions. Your immune system may attack the donor material, leading to dangerous and even fatal reactions.

Your doctor may order blood typing, crossmatching, or both if:

  • you’re scheduled to receive a blood transfusion or organ transplant
  • you’re scheduled to undergo a medical procedure where you face the risk of significant blood loss
  • you have certain medical conditions, such as severe anemia or a bleeding disorder

Your doctor may also order blood typing if you’re pregnant. If your developing fetus has a different blood type than you, it raises their risk of developing a type of anemia called hemolytic disease.

Blood typing

Blood typing helps your doctor determine what type of donor blood is compatible with your own. Some blood types contain antibodies that trigger immune reactions against other blood types. In general:

  • if you have type A blood, you should only receive types A or O blood
  • if you have type B blood, you should only receive types B or O blood
  • if you have type AB blood, you can receive types A, B, AB, or O blood
  • if you have type O blood, you should only receive type O blood

If you have type AB blood, you’re known as a “universal recipient,” and can receive any ABO category of donor blood. If you have type O blood, you’re known as a “universal donor,” and anyone can receive type O blood. Type O blood is often used in emergencies when there isn’t enough time to perform blood typing tests.

Crossmatching

Crossmatching can also help reveal if specific donor blood or organs are compatible with your own. In addition to anti-B and anti-A antibodies, other types of antibodies may be present in your blood that negatively interact with donor materials.

How are these tests performed?

To perform blood typing and crossmatching, your doctor will collect a sample of your blood to send to a laboratory for testing.

Collecting the sample

A trained healthcare practitioner can draw a sample of your blood at your doctor’s office, blood bank, or other sites. They’ll use a needle to draw the sample from one of your veins, usually on the inside of your elbow.

They’ll likely start by disinfecting the area with an antiseptic. An elastic band will be placed around the upper part of your arm, causing your vein to swell up with blood. A needle that they gently inserted into your vein will collect a sample of your blood in a tube.

Once they’ve collected enough blood, the practitioner will remove the needle and unwrap the band from your arm. The puncture site will be cleaned, and if needed, bandaged. Your blood sample will then be labeled and sent to a laboratory for testing.

Blood typing the sample

In the laboratory, a technician can conduct several tests to type your blood.

They will mix some of your blood with commercially prepared anti-A and anti-B antibodies. If your blood cells agglutinate, or clump together, it means your blood has reacted with one of the antibodies.

Next, the technician will perform back typing. This calls for some of your blood to be mixed with type A and type B blood. Your blood with then be checked for signs of reaction.

Following that, the technician will perform Rh typing. This is when they mix some of your blood with antibodies against Rh factor. Signs of any reaction will be noted.

Crossmatching the sample

To crossmatch your blood against donor blood or organs, the technician will mix a sample of your blood with a sample of the donor material. Again, they’ll check for signs of reaction.

What do the test results mean?

Depending on the results of your blood typing, your blood will be classified as type A, B, AB, or O. It will also be classified as Rh+ or Rh-. There is no “normal” or “abnormal” blood type.

The results of your crossmatching test will help your doctor assess if it’s safe for you to receive specific donor blood or organs.

Commercial antibodies

If your blood cells clump only when mixed with:

  • anti-A antibodies, you have type A blood
  • anti-B antibodies, you have type B blood
  • either anti-A or anti-B antibodies, you have type AB blood

If your blood cells don’t clump when mixed with either anti-A or anti-B antibodies, you have type O blood.

Back typing

If your blood cells clump only when mixed with:

type B blood, you have type A blood
type A blood, you have type B blood
type A or B blood, you have type O blood

If your blood cells don’t clump when mixed with either type A or B blood, you have type AB blood.

Rh typing

If your blood cells clump when mixed with anti-Rh antibodies, you have Rh+ blood. If they don’t clump, you have Rh- blood.

Crossmatching:

If your blood cells clump when mixed with a donor sample, the donor blood or organ is incompatible with your blood.

What are the risks?

Blood draws are generally safe for most people, but they do pose some risks. You may experience some discomfort or pain when the needle is inserted. You may also develop bleeding, bruising, or infection at the puncture site.

In most cases, the potential benefits of blood typing and crossmatching outweigh the risks. Talk to your doctor to learn more about the procedure. They can also help you understand your test results and recommend appropriate follow-up steps.

Source: Click This Link

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What is Blood?

Blood is a constantly circulating fluid providing the body with nutrition, oxygen, and waste removal. Blood is mostly liquid, with numerous cells and proteins suspended in it, making blood "thicker" than pure water. The average person has about 5 liters (more than a gallon) of blood.

About Blood Donation

A blood donation occurs when a person voluntarily has blood drawn and used for transfusions and/or made into biopharmaceutical medications by a process called fractionation (separation of whole-blood components). Donation may be of whole blood (WB), or of specific components directly (the latter called apheresis). Blood banks often participate in the collection process as well as the procedures that follow it.

More Facts

A liquid called plasma makes up about half of the content of blood. Plasma contains proteins that help blood to clot, transport substances through the blood, and perform other functions. Blood plasma also contains glucose and other dissolved nutrients.

About half of blood volume is composed of blood cells:

• Red blood cells, which carry oxygen to the tissues
• White blood cells, which fight infections
• Platelets, smaller cells that help blood to clot

Blood is conducted through blood vessels (arteries and veins). Blood is prevented from clotting in the blood vessels by their smoothness, and the finely tuned balance of clotting factors.

Blood Conditions

Hemorrhage (bleeding): Blood leaking out of blood vessels may be obvious, as from a wound penetrating the skin. Internal bleeding (such as into the intestines, or after a car accident) may not be immediately apparent.

Hematoma: A collection of blood inside the body tissues. Internal bleeding often causes a hematoma.

Leukemia: A form of blood cancer, in which white blood cells multiply abnormally and circulate through the blood. The abnormal white blood cells make getting sick from infections easier than normal.

Multiple myeloma: A form of blood cancer of plasma cells similar to leukemia. Anemia, kidney failure and high blood calcium levels are common in multiple myeloma.

Lymphoma: A form of blood cancer, in which white blood cells multiply abnormally inside lymph nodes and other tissues. The enlarging tissues, and disruption of blood's functions, can eventually cause organ failure.

Anemia: An abnormally low number of red blood cells in the blood. Fatigue and breathlessness can result, although anemia often causes no noticeable symptoms.

Hemolytic anemia: Anemia caused by rapid bursting of large numbers of red blood cells (hemolysis). An immune system malfunction is one cause.

Hemochromatosis: A disorder causing excessive levels of iron in the blood. The iron deposits in the liver, pancreas and other organs, causing liver problems and diabetes.

Sickle cell disease: A genetic condition in which red blood cells periodically lose their proper shape (appearing like sickles, rather than discs). The deformed blood cells deposit in tissues, causing pain and organ damage.

Bacteremia: Bacterial infection of the blood. Blood infections are serious, and often require hospitalization and continuous antibiotic infusion into the veins.

Malaria: Infection of red blood cells by Plasmodium, a parasite transmitted by mosquitos. Malaria causes episodic fevers, chills, and potentially organ damage.

Thrombocytopenia: Abnormally low numbers of platelets in the blood. Severe thrombocytopenia may lead to bleeding.

Leukopenia: Abnormally low numbers of white blood cells in the blood. Leukopenia can result in difficulty fighting infections.

Disseminated intravascular coagulation (DIC): An uncontrolled process of simultaneous bleeding and clotting in very small blood vessels. DIC usually results from severe infections or cancer.

Hemophilia: An inherited (genetic) deficiency of certain blood clotting proteins. Frequent or uncontrolled bleeding can result from hemophilia.

Hypercoaguable state: Numerous conditions can result in the blood being prone to clotting. A heart attack, stroke, or blood clots in the legs or lungs can result.

Polycythemia: Abnormally high numbers of red blood cells in the blood. Polycythemia can result from low blood oxygen levels, or may occur as a cancer-like condition.

Deep venous thrombosis (DVT): A blood clot in a deep vein, usually in the leg. DVTs are dangerous because they may become dislodged and travel to the lungs, causing a pulmonary embolism (PE).

Myocardial infarction (MI): Commonly called a heart attack, a myocardial infarction occurs when a sudden blood clot develops in one of the coronary arteries, which supply blood to the heart.

Source: WebMD

Today in the developed world, most blood donors are unpaid volunteers who donate blood for a community supply. In some countries, established supplies are limited and donors usually give blood when family or friends need a transfusion (directed donation). Many donors donate as an act of charity, but in countries that allow paid donation some donors are paid, and in some cases there are incentives other than money such as paid time off from work. Donors can also have blood drawn for their own future use (autologous donation). Donating is relatively safe, but some donors have bruising where the needle is inserted or may feel faint.

Potential donors are evaluated for anything that might make their blood unsafe to use. The screening includes testing for diseases that can be transmitted by a blood transfusion, including HIV and viral hepatitis. The donor must also answer questions about medical history and take a short physical examination to make sure the donation is not hazardous to his or her health. How often a donor can donate varies from days to months based on what component they donate and the laws of the country where the donation takes place. For example, in the United States, donors must wait eight weeks (56 days) between whole blood donations but only seven days between plateletpheresis donations and twice per seven-day period in plasmapheresis.

The amount of blood drawn and the methods vary. The collection can be done manually or with automated equipment that takes only specific components of the blood. Most of the components of blood used for transfusions have a short shelf life, and maintaining a constant supply is a persistent problem. This has led to some increased interest in autotransfusion, whereby a patient's blood is salvaged during surgery for continuous reinfusion—or alternatively, is "self-donated" prior to when it will be needed. (Generally, the notion of "donation" does not refer to giving to one's self, though in this context it has become somewhat acceptably idiomatic.)

Who can give blood

Most people can give blood. You can give blood if you:

  • are fit and healthy
  • weigh between 7 stone 12 lbs and 25 stone, or 50kg and 160kg
  • are aged between 17 and 66 (or 70 if you have given blood before)
  • are over 70 and have given blood in the last two years

How often can I give blood?

Men can give blood every 12 weeks and women can give blood every 16 weeks. Find out more about what happens on the day of your donation.

Check you are able to give blood

You can check some of the most common eligibility questions we receive from blood donors.

You can register here as a blood donor.

The common reasons donors should check if they can give blood are:

  • if you are receiving medical or hospital treatment
  • if you are taking medication
  • during and after pregnancy
  • if you feel ill
  • if you have cancer
  • after receiving blood, blood products or organs.

Women under 20 - check if you can give blood.

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