TRANSFUSION MEDICINE
Transfusion medicine comprises of blood and blood component transfusion.
Blood cannot be synthesized artificially. So, the source of blood is from a
healthy human donor.
Blood Transfusion
Blood transfusion is the process of transferring blood/blood products from
donor into the circulating system of recipient. It is important to properly
collect the blood from donor, prepare its components (if required) and storeblood/components in a proper way and transfuse in such a way to avoid any
risks or hazards.
Donor Selection
Q. Criteria for selection of blood donor.
Donor selection is based on medical history and few routine physical
examinations (weight, blood pressure, temperature, hemoglobin) are done to
know whether donor is suitable for donating blood.
v Donor should be healthy. There are three types of donors namely
voluntary (should be encouraged), replacement and professional.
v Age: Donor should be between 18-65 years of age.
v Weight: Should be >45 kg.
v Blood pressure should be normal and not a diabetic on insulin or
uncontrollable sugar levels.
v Time interval between each blood donation should be 3 months.
v No skin disease at the phlebotomy site.
v It is important to know whether the patient has history of diseases like
hepatitis, AIDS, syphilis and if so, blood should not be obtained from
them.
Collection of Blood
Blood is collected under aseptic conditions using sterile, plastic bag with
anticoagulant. Now CPD-A is used as an anticoagulant. Mix the blood and
anticoagulant gently and periodically during its collection.
Q. Write short answer on anticoagulants used in blood
bank.
Anticoagulants used: The different anticoagulants-preservative solutions
available are as follows:
v Citrate phosphate dextrose (CPD).
v Citrate phosphate dextrose adenine-1 (CPDA-1)
v Acid citrate dextrose (ACD) is not used nowadays.Q. Write short answer on functions of each
component of CPDA-1.
Functions of various chemical used is mentioned in Table 15.1.
Storage of blood: Blood is stored in a refrigerator at 2°–6°C.
Predonation Check-Up
Q. Write short answer on screening of blood donor.
Donor blood: The following tests are routinely carried out on donor’s blood:
v ABO and Rh grouping.
v Tests for:
n HBsAg, anti-HCV, anti-HIV-1 and HIV-2 and serum alanine
aminotransferase (ALT).
n Malaria and syphilis.
Recipient blood: The recipient’s ABO and Rh grouping are also carried out.PRETRANSFUSION AND COMPATIBILITY
TESTING
Q. Write short answer on screening of blood unit
before transfusion (pretransfusion tests).
Indications: Before transfusion of any blood or its components, it is
essential to know whether they are compatible with the recipient’s blood.
This is achieved by performing a set of procedures known pretransfusion
testing also referred to as compatibility testing. These set of procedures
(serologic and nonserologic protocols) are required before blood is issued
as being compatible. A compatibility testing is an entire quality process
composed of many procedures (steps). It is designed to provide the safest
blood product possible for the recipient of the transfusion. Sometimes, the
term compatibility test and cross-matching are used interchangeably, but
crossmatch is only a part of compatibility test. List of compatibility tests are
presented in Box 15.3.
Crossmatching (Crossmatch Testing)
Q. Write short answer on crossmatching.
The term crossmatch is a crossway mixing of donor and recipient blood
components. In crossmatching, the serum or plasma from the recipient is
mixed with red cells from the donor. A crossmatch is only one part of
pretransfusion (compatibility) testing and is very important before any blood
transfusion. Crossmatching should be carried out to ensure that there are no
antibodies in patient’s serum that will react with the donor’s cells when
transfused. Crossmatching is routinely done only with donor products
containing red cells, hence must be performed for red cell transfusions.
Hemolysis or agglutination at any phase or step of the crossmatch process
indicates that the antibodies present in the recipient interact with donorred cell antigens and a mismatch between donor and recipient. A crossmatch
is considered as compatible when there is neither agglutination nor
hemolysis in testing and the donor unit is acceptable for transfusion
purposes. A cross-match is considered as incompatible when there is
presence of either agglutination or hemolysis.
Importance of Crossmatching
v It is the final check of ABO compatibility between donor and recipient.
v Detects the presence of any clinically significant, unexpected antibodies in
the recipient’s serum that may react with donor’s cells, thereby
preventing any transfusion reaction.
v A thorough crossmatching is performed with recipient’s serum and
donor’s red cells.
Types
Crossmatching procedure may be divided into two major parts, namely, (i)
major and (ii) minor crossmatching (Table 15.2).Serological Crossmatch Techniques
Major serological crossmatch test consists of testing the patient’s
(recipient’s) serum with donor RBCs (Box 15.3). The routinely used twoserological methods are— (i) immediate-spin (IS) crossmatch, and, (ii) an
indirect antiglobulin test (IAT) crossmatch. In both these serologic
crossmatch procedures, the recipient’s serum or plasma is tested with the red
cells from the donor unit.
Principles of Serological Testing
The pretransfusion testing is performed to detect in vitro red cell antigen and
antibody reaction by observing for either agglutination or hemolysis. Only
one serological method namely immediate-spin (IS) crossmatch is discussed
here.
Immediate-spin Crossmatch
This is the simplest serologic test to detect most ABO incompatibility in
which the recipient’s serum or plasma is mixed with donor’s red cell
suspensions and centrifuging immediately (i.e., immediate spin). Then
observe it for agglutination. Absence of hemolysis or agglutination
indicates ABO compatibility. This serologic test is used to detect ABO
incompatibility and is enough to rule out any ABO grouping error. In this
method, there should not be any delay in the centrifugation step or reading
the reaction.
Advantages: IS crossmatch procedure requires less turn-around time,
workload, and reagent cost compared to full AHG crossmatch.
Disadvantages: This method does not detect all ABO incompatibilities
and is inadequate for detection of clinically significant IgG type of
antibodies.
Procedure for immediate-spin crossmatch (Fig. 15.2):
v Take two drops of patient’s serum/plasma in a prelabelled glass test tube.
v Add one drop of 3–5% saline of suspension of donor red cells. Cells
usually are washed once to remove any anticoagulant or plasma protein
which may interfere with the testing.
v Mix the contents and incubate for 5–10 minutes for IS method or for 45–
60 minutes for saline room temperature technique.
v Immediately centrifuge the tube at 1,000 rpm for 1 minute (IS method).
While in case of saline room temperature technique, centrifugation is
optional.v Gently dislodge the cell button and examine the tube for the presence or
absence of hemolysis or agglutination.
This procedure is known as the abbreviated or IS crossmatch.
Interpretation:
v Positive test: If hemolysis or agglutination is present at this stage, the test
is considered as reactive/positive. It indicates that the unit selected may
be ABO incompatible and the unit is not considered acceptable for
transfusion (crossmatch is incompatible).
v Negative test: If there is no hemolysis or agglutination, test is
considered as nonreactive/negative and the unit is considered acceptable
for transfusion (compatible).
It is always necessary to monitor the recipient during and after transfusion so
that any complications can be dealt accordingly. Presently indirect
antiglobulin technique (by gel card technology) is used in blood banks. In concise form for exams