Clinical Laboratory - Transfusion Medicine

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Blood Donors

There is always a need for blood donors. Modern medical care, including surgery and medical treatment for many diseases, is not possible without the use of blood products. A shortage of blood products means that someone may not get prompt, adequate care.

In order to insure patient safety, potential donors undergo thorough screening in order to eliminate unsuitable candidates. Criteria that must be satisfied before donation include:

  • Medical history, with an acceptable Hemoglobin level and no current prescriptions that may cause problems when donating

  • Good physical health and feeling well on the day of donation

  • Possible contact with transfusion-transmissable infectious diseases through sexual history, drug use and travel

  • Photo identification

  • At least 56 days have passed since prior donation.

These criteria are covered in a complete health questionnaire and confidential interview that must be completed during each donation. Failure to follow strict adherence to the established protocol increases the risk for injury to potential recipients.

Blood donation may come from a variety of donors, which include autologous and directed donors.

Autologous Donors

An "autologous" donation occurs when a person donates his or her own blood for personal use. This means that, since the blood is not be be used for anyone else, then units positive for infectious agents and units with irregular blood group antibodies are still acceptable for autologous donation.

However, because of the potential risk for a clerical error with mistransfusion of an autologous unit in the inventory, units positive for hepatitis B (HBsAg) and human immunodeficiency virus (HIV) are not allowed into the Blood Bank. If an autologous unit is collected but not used by the patient-donor, then it is destroyed.

There are three other ways, aside from the "predeposit" of blood as outlined above, to make use of the patient's own blood:

  • Hemodilution: the patient's blood is collected prior to surgery and replaced with a plasma expander. The theory is that any bleeding during surgery will lose fewer RBCs. Then the previously collected, higher hematocrit blood can be given back to the patient following surgery.

  • Cell Saver: this device is used to collect blood in the operative field during surgery, wash it, and return it with saline to the patient. This is done to minimize blood loss, and it is a cheaper option than the transfusion of PRBC. This will work as long as the operative field is not contaminated with bacteria or with malignant cells.

  • Wound drainage: blood is collected from cavities (such as a joint space into which bleeding has occurred) and returned through a filter (which removes big items like thrombi and tissue fragments, but does not remove inflammatory chemical mediators or cytokines).

Directed Donors

A "directed" donation occurs when the potential recipient of blood or blood products designates certain persons to donate specifically for his or her use. In general, blood collected from directed donations is no safer than that of the general blood supply because of the stringent screening and testing of volunteer donors that ordinarily occurs. Problems with directed donations include:

  • Confidentiality of the donor is difficult to maintain.

  • The donor may not want to answer the exclusionary questions of the blood safety form and health questionnaire properly.

  • This procedure is not cost-effective.

  • There are contraindications, such as an increased risk for transfusion-asscociated graft versus host disease (TAGVHD), alloimmunization of potential recipients of transplants, and increased risk for hemolytic disease of the newborn in mothers receiving blood from fathers.

There is a small but significant risk for TAGVHD in persons receiving blood from relatives, because of similar genetic makeup. TAGVHD is fatal, with no effective treatment.

Patients who request directed donations from family and friends often do not realize the pressure such a request can place upon an individual who does not qualify to donate blood. That individual, if answering the questions in the interview properly, will be excluded from donating, which will result in family members asking questions about why the blood was not accepted. The alternative is answering the questions untruthfully and compromising the safety of the blood products collected.

Alternatives to Blood Products

Persons with chronic anemia may be given synthetic erythropoietin ("Epo") to boost RBC production.

Granulocyte/monocyte-colony stimulating factor (GM-CSF) can be administered as the drug filgastrim to boost leukocyte production, particularly in persons undergoing chemotherapy, or to aid engraftment following hematopoietic stem cell transplantation.

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