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Crossmatch and Processing
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.
Whole blood is collected from healthy donors who are required to meet strict criteria concerning:
Possible contact with transfusion-transmissible infectious diseases, including a history of:
Travel to areas of endemic disease (e.g., malaria)
A photo identification is required for all donors. The potential donor must:
Be in good health and feeling well on the day of donation.
Be on no prescribed medication that would cause the donor a problem when donating or that would affect the recipient
Have a hemoglobin (red blood cell) level which meets the established U.S. Food and Drug Administration (FDA) standard.
Wait 56 days before giving another donation of whole blood.
All donors are required to complete a health questionnaire and blood safety form during a confidential interview by a donor center health care worker each time they come in to donate blood. The purpose of this process is to determine whether a donation can be obtained safely.
Please note that AIDS and other infectious diseases CANNOT be transmitted to a blood donor. The equipment used to collect blood is sterile, used only once and then discarded. There is NO risk of contracting AIDS or any other infectious disease by donating blood.
In the interview process a questionnaire is filled out. The questions are designed to identify potential health problems for the donor or potential infections that may be present in the donor that could be transmitted through transfusion to another person.
A fingerstick yields a drop of blood for testing to determine if the donor has a high enough hematocrit to safely donate blood.
The blood is drawn into a capillary tube which is then spun in the small centrifuge (seen in the background) to determine the hematocrit.
The donor sits in a reclining chair. An inflatable cuff on the arm is used to check blood pressure and to maintain venous filling.
The site for drawing blood is selected and disinfected. A prominent vein is chosen for the venipuncture site.
The disinfectant is applied to the area around the vein to be used.
The needle used to draw the blood from the vein is gently inserted.
Blood fills the collection bag by gravity in a few minutes. The sealed plastic collection bag contains a blood preservative.
Just after the bag has filled, blood from the line is taken to fill several vacutainer tubes for further testing.
The needle is removed and pressure is applied over the venipuncture site, then a bandage is placed for the next couple of hours.
The donor drinks some liquid (here a tube of apple juice) to replace the lost blood volume, eats some cookies, and is on his way in about 10 minutes.
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 RBC's. 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 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).
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.
Additional 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. Thus, all units of blood collected by directed donation typically undergo gamma irradiation to destroy any white blood cells that could cause TAGVHD. This adds significantly to the cost of blood processing, and these units must be discarded if not used within 24 hours.
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.
Go to the section on blood testing.
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