b. The recipient and the blood sample must be positively identified, when the
sample for compatibility testing is drawn. One way, of positive identification, is to ask
the patient to state his full name, not merely to confirm it. If the patient is unable to state
his name, the wristband must be relied upon totally for information. When a wristband
(or other identification attached to the person) is not available, it is necessary to confirm
the identification with a professional person familiar with the patient. Bed labels should
not be used in place of wristbands. The unidentified emergency patient should be given
a temporary identify number (attached to his person) that can be used until positive
identification is made.
c. The wristband should then be checked, and the name and identification
number should be copied from the source onto the tube label, with an indelible marker.
If imprinted labels are used, the information on the labels should match the wristband
exactly. The date should then be added, and the identification compared to the request
form. Other pertinent data may appear on the tube label, such as, initials of the person
responsible for collecting the recipient sample. The tube must be labeled immediately
before, or after, the blood is drawn at the bedside of the recipient. Ordinarily, the
sample should not be drawn from tubing used for infusion of intravenous fluid or from
the contiguous vein, but from a fresh venipuncture site. If the tubing must be used, it
should be flushed with saline and the first 5 ml of blood withdrawn should be discarded.
1-44. PRETRANSFUSION TESTING OF THE RECIPIENT
The information on the request form and sample label must be compared by a
qualified person before testing can begin. In case of discrepancy or doubt concerning
the specimen, a new sample must be drawn.
a. Patient Specimen.
(1) Fresh, not inactivated serum, less than 72 hours old must be used for
the crossmatch. If plasma is used, fibrin clots may form and interfere with the test and
with complement activation.
(2) When a series of transfusions is to be given over a period of several
days, a new sample of the recipient's blood obtained within 72 hours of the next
scheduled transfusion should be used. This is essential for the detection of antibodies
that may appear in the recipient's circulation in response to blood previously transfused.
If more than 72 hours have elapsed since the previous transfusion, units of donor blood
previously crossmatched must be recrossmatched with a new patient serum specimen
(3) Hemolyzed patient samples should be avoided because they may mask
hemolysis of donor RBCs.