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Blood and Blood
Ordering Blood or Blood Products
|The request for transfusion of blood and blood
products must be made by a physician since blood is considered a drug. The patient's clinical and
laboratory tests must meet some minimum requirements. These minimum
requirements can be found in the Laboratory Survival Guide or by
|Type and Screen versus a
Type and Crossmatch
Screen: The blood bank staff will perform all necessary testing on
the patient's sample. Until a request is received for blood, units will not be crossmatched and
set aside in
the blood bank for that patient. However, once a request for
blood is received, blood can be made available in as little as five
minutes. This order should be used when the
likelihood of the patient needing a blood transfusion is slight.
and Crossmatch: The blood bank staff will perform all necessary
testing on the patient's sample AND crossmatch the number of units
requested. In the blood bank, these units will be set aside for the
patient and are immediately available once the physician
determines there is a need to transfuse the patient..
physician does not anticipate the need for a blood transfusion but the
potential is there, a type and screen should be requested. A type
and cross should be requested whenever a transfusion is expected or very
likely. This is more important during periods of blood shortages.
During these shortage periods, the blood bank staff may decide to not hold
or crossmatch blood for a patient unless an order to transfuse has be received.
blood sample from the patient must be no older than three days. If a blood sample is collected on Monday, that sample will be good until
Thursday at midnight. Another sample for additional transfusions
must be drawn Friday.
sample of blood must be drawn in a purple top tube (EDTA
samples received for a type and cross or a type and screen are tested for:
ABO antigens and antibodies, Rh(D)
antigen, and the presence of antibodies to different red cell antigens. The later is termed
an antibody screen. There are over 400 known antigens that can be
present or absent on Red Blood Cells. During a transfusion or
pregnancy, patients may be exposed to different red
blood cell antigens that may result in antibody formation by the patient.
If these antibodies are not detected, they can destroy the transfused red
blood cells. However, not everyone will form these red cell antibodies.
Because it is difficult to determine who may have been exposed
to other red cell antigens, all patient samples are tested or
"screened" for these antibodies.