Test De Transfucion Sanguinea

ABC of Transfusion

TESTING BEFORE TRANSFUSION, AND BLOOD ORDERING POLICIES
Marcela Contreras, P L Mollison

If tests are done to ensure that donor and recipient belong to the same blood group (ABO) then - even if no other tests are done - the donor's red cells will be compatible with the recipient's plasma in about 97% of cases. In practice the presence of the Rh D antigen on the red cellsof donors and recipients is also determined, mainly so that Rh positive red cells will not be given to an Rh negative recipient. This procedure not only prevents accidental induction of Rh immunisation but also ensures that Rh positive red cells are not transfused to those patients (about 1% of recipients) who have already developed Rh antibodies. Thus when donor and recipient belong to the sameABO and Rh groups, the transfusion will be compatible in about 98% of cases.
,______ j X

elaborate procedure.

To ensure compatibility in the remaining 2% serological tests must be -carried out to identify other antibodies that may be present in the recipient's blood. Because compatible blood can readily be found for most recipients there is a tendency for doctors to regard blood as astandard pharmaceutical product that can be made available at short notice. It must not be forgotten that safety can be maintained only by carrying out elaborate tests, and these take time.

Blood grouping and antibody screening
As soon as it has been decided that a patient needs (or is reasonably likely to need) a transfusion, one sample of clotted blood and one sample that has been anticoagulated inEDTA should be sent, together with a properly completed request form, to the hospital transfusion laboratory. In patients who may have developed antibodies it is important that the samples should be taken only a short time before transfusion. In practice, if patients have received transfusions or been pregnant within three months the samples should be taken within 48 hours, and if patients havereceived transfusions less than 10 days previously samples should be taken within 24 hours of the planned transfusion. The request form should contain the name of the
clinician responsible for the patient as well as clear and detailed

0

Blood group B A
A

AB A+B

Antigens on red (and other) cells
in United Kingdom

None

B

anti-AB anti-B anti-A None Antibody in serum Approximatepercentage

47

42

8

3

identification of the patient (full name, date of birth, hospital index number, and address). Details of the diagnosis and of potentially sensitising episodes-for example, pregnancy, transfusion, or transplantation-are essential. The number of units of blood required (if any), the degree of urgency, and the expected date of transfusion should also be stated.Incomplete transfusion request forms should not be accepted by hospital transfusion departments.
BMJ
VOLUME

1446

299

9 DECEMBER 1989

Most deaths associated with blood transfusion are still the result of mistakes in identification, and some of them occur at the stage of taking blood from a potential recipient. Steps that should be taken to avoid such mistakes are: (1) The tubescontaining blood samples should be clearly labelled with the patient's full name, date of birth, and hospital index number.
(2) The person taking the blood sample must ensure that the patient is properly identified, either by speaking to the patient or-if the patient is unconscious-by examining the wrist band. Ideally, the tubes should be labelled after they have been filled with blood. (3) There shouldbe no discrepancy between the information on the request form and that on the tubes.

The two tubes containing the patient's blood must be clearly labelled.

(4) For those patients with previous blood bank records the current information must be identical with that on the old records.
OE
Group A red cells

* *

IgM anti-A

* Blood grouping The patient's red cells are grouped for ABO...