Bloodbanking

The Immunohematology Laboratory is responsible for properly matching the blood types of donors and recipients in order for the patient to receive a safe blood transfusion. The imunohematology lab is commonly referred to as the blood bank. In addition to typing blood, the blood bank must also prepare Fresh Frozen Plasma, Cryoprecipitated Anti Hemophiliac Factor, Platelet concentrates, Rh Immune Globulin, and perform antibody screening.

Early attempts to transfer blood from one person to another produced varied results. Sometimes the person receiving the transfusion was aided by the procedure. Other times the recipient suffered a blood reaction in which the red blood cells clumped together, obstructing vessels and producing other serious consequences. Eventually, it was discovered that human blood is not all alike. Instead, each individual was found to have a particular combination of substances in his or her blood. Some of these substances reacted with those in another person's blood. These discoveries led to the development of procedures for typing blood. It is known that safe transfusions of blood depend upon properly matching the blood types of the donors and the recipients.

The clumping of red cells following a transfusion reaction is called agglutination. This phenomenon is due to the presence of substances called agglutinogens (Antigens) in the red cell membranes and substances called agglutinins (antibodies) dissolved in plasma.BO blood typing involves identifying the antigens present on a persons red cells and antibodies present in a persons serum. Although there are many different antigens associated with human red cells, only a few of them are likely to produce a hemolytic transfusion reaction. These include the antigens of the ABO and Rh groups. Avoiding the mixture of certain kinds of antigens and antibodies prevents adverse transfusion reactions.

Blood typing involves determining what antigens are on the patients red cells and what antibodies are in the patients serum. The most common blood typing involves determining a patient ABO and Rh group. There are four ABO types:

1. Type A

2. Type B

3. Type O

4. Type AB

There are 2 Rh blood types:/p>

1. Rh Positive

2. Rh Negative

The following table explains the differences in the above blood types.

* If an Rh negative patient receives blood from an Rh positive donor the negative patient may produce an antibody called Anti-D which may cause a serious transfusion reaction the next time the patient receives Rh Positive Blood. It is not standard practice for the blood bank to issue Rh positive blood to an Rh negative recipient.

Question and Answers

Q Can my family or friends donate blood especially for me?

Yes, they can. If you are not a candidate for autologous donation, you can select friends and family who will donate blood for use by you. This type of donation is called a "directed donation".

Please call your local American Red Cross or Crestwood Medical Center Blood Bank (205-880-4165) for more information on this type donation.

Q What happens to my "directed donor" blood units?

After you leave the hospital and it has been established that you will not need your "directed donor" blood, the blood bank can return it to the regular blood stock so that other patients in need of blood can receive it before it expires. Since this blood came from other people, directed for your use, the usual testing was carried out, ensuring that the blood contained no infectious agents that could be passed to you from their blood.

Q What is a "universal donor"?

In an emergency, if blood must be released from the blood bank before crossmatching has been performed, the universal donor, Blood Type O, is selected. It is felt that group O red cells can be safely transfused into a person with any ABO blood type, because the patient's serum cannot contain an antibody to group O cells. In other words, a major reaction cannot occur.

However, since Type O blood does contain anti-A and anti-B antibodies, if it is given to group A, group B, or group AB persons, a reaction can occur. So, Type O blood is NOT a universal recipient.

It is important to point out that blood is never given to patients without thoroughly crossmatching donor blood with the patient's blood, unless it is an emergency situation which will not allow for the time required for crossmatching. Even in these cases, a crossmatch is performed as soon as possible, while the blood is transfusing, or even after the blood has been transfused.

Q What is the "universal recipient"?

The "universal recipient" is type AB.

Q How can I find out my blood type?

You can ask your physician to write an "order" to type your blood. Bring the "order" to Crestwood Medical Center and register with outpatient services. Laboratory personnel will then draw a blood sample and type your blood.

Q How long does it take to type my blood?

It usually takes from 15 - 30 minutes to perform your blood type.

Q How long does it take to perform a crossmatch?

A blood specimen must be obtained from you to crossmatch the donor blood against. After that, we must wait for the blood to clot so that we can separate the blood cells from the serum. (Special tubes are available which speed up this process.) It then takes about 45 minutes to complete the crossmatch

Q If I am bleeding severely, how long will it take to start a transfusion?

In an emergency, if you were losing blood severely, a blood specimen first would be obtained from you to do subsequent crossmatching, and "emergency release blood", Type O, would be obtained from the blood bank and transfused in you immediately, until a crossmatch could be completed. At that time you would receive only crossmatched blood. The transfusion of "emergency released" blood could be started in as little as 5 to 10 minutes.

Q Does it hurt to receive a blood transfusion?

Normally the only pain involved in receiving a blood transfusion results from the insertion of the IV needle.

Q If I have a antibody in my blood that has caused me to react to blood products in the past, should I tell someone when I get to the hospital?

Yes, tell your nurse and/or doctor so that they may inform the blood bank of your problem.

Q What qualifications do the employees performing crossmatches have?

Most Medical Technologists (MT's) have a Bachelor of Science degree in Laboratory Technology, Chemistry and/or Biology. All MT's have at least one year of post- graduate training in a certified Medical Technology Training Program. Laboratory personnel are then certified nationally by taking an examination given by ASCP, NCA, AMT and/or HEW.