IIntended L Learning O Outcomes (ILOs)

Compatibility TestingApproaches Requiring Less Than a

Complete CrossmatchIs the Crossmatch Really Needed?What can be given in an emergency

transfusion?

Compatibility testing is done to avoida hemolytic transfusion reaction

If the Host or Recipient recognizesthe donor RBC surface antigens as foreign,the host will mount an immune response

to the donor RBC’s

ABO

ABO blood group antigens present on red blood cells and IgM antibodies present in the serum

Rhesus47 Antigens make up the Rhesus Blood Group

The most significant is the D antigen

What is compatibility testing?Also called pretransfusion testingPurpose:

To select blood components that will not cause harm to the recipient and will have acceptable survival when transfused

If properly performed, compatibility tests will confirm ABO compatibility between the component and the recipient and will detect the most clinically significant unexpected antibodies

Compatibility testingCan be divided into 3 categories:

Preanalytical proceduresSerological testingPostanalytical procedures

Patient IdentificationMust confirm

recipient’s ID from bracelet ON the patientFull patient name

and hospital numberName of physician

http://www.usatoday.com/tech/news/techinnovations/2006-07-17-chips-everywhere_x.htm

Sample IdentificationThe sample should

also have the full patient name, hospital number, and physician

Date and time of collection, phlebotomist’s initials

All of this should be on the request form and the sample

Specimen Tubes

Pink Top - EDTA Red Top – no additives

Serological Testing3 tests:

ABO/RhAntibody detection/identificationCrossmatch

ABO/Rh TypingIn the ABO typing, the forward and reverse

MUST matchIn the Rh typing, the control must be

negativeBoth of these will indicate what type of blood

should be given

Anti A Anti B Anti A Anti B

Anti A Anti B Anti A Anti B

A B

OAB

Antibody screenAlso called the Also called the indirect Coombs testindirect Coombs test or the or the

indirect antiglobulin testindirect antiglobulin testThe antibody screen will detect the

presence of any unexpected antibodies in patient serum

If antibodies are detected, identification should be performed using panel cells (with an autocontrol)IS37° (LISS)AHG

CrossmatchingPurpose:

Prevent transfusion reactionsIncrease in vivo survival of red cellsDouble checks for ABO errorsAnother method of detecting antibodies

Crossmatches According to the AABB Standards:

The crossmatch “shall use methods that demonstrate ABO incompatibility and

clinically significant antibodies to red cell antigens and shall include an antiglobulin

phase”

Donor RBCs (washed)

Patient serum

No agglutination ~ compatible

Agglutination ~ incompatible

The procedureDonor cells are

taken from segments that are attached to the unit itself

Segments are a sampling of the blood and eliminate having to open the actual unit

Crossmatch Procedure if antibodies are NOT detected:

Only immediate spin (IS) is performed using patient serum and donor blood suspension

This fulfills the AABB standard for ABO incompatibility

This is an INCOMPLETE CROSSMATCHIf antibodies ARE detected:

Antigen negative units found and X-matchedAll phases are tested: IS, 37°, AHGThis is a COMPLETE CROSSMATCH

WillVerify donor cell ABO compatibility

Detect most antibodies against donor cells

Will NotGuarantee normal survival of RBCs

Prevent patient from developing an antibody

Detect all antibodies

Prevent delayed transfusion reactions

Type and Screen

Determines the ABO-Rh of the patient and the presence of the most commonly found unexpected antibodies(elimination of the crossmatch ).

Type and Screen

If an emergency transfusion is required after type and screen alone, an immediate-phase crossmatch is performed.

Blood given in this manner is more than 99% effective in preventing incompatible transfusion reactions due to unexpected antibodies.

Is the Crossmatch Really Needed?If the correct ABO and Rh blood type is

given, the possibility of transfusing incompatible blood is less than 1 chance in 1000.

ABO-Rh typing alone results in a 99.8% chance of a compatible transfusion,

The addition of an antibody screen increases the safety to 99.94%, and

A crossmatch increases this to 99.95%.

Physician responsibility in ordering uncrossmatched blood

In an emergency (ER or OR), there may not be enough time to test the recipient’s sample

It is your judgment that the risk of the patient dying from from anemia is greater than the risk of transfusing the patient without pre-transfusion testing

What can be given in an emergency?

Type-Specific, Partially Crossmatched Blood An ABO-Rh typing and an immediate-phase

crossmatchAn abbreviated format Macroscopic agglutination. This takes 1 to 5 minutes

What can be given in an emergency?Type-Specific, Uncrossmatched Blood

The ABO-Rh type Most ABO type-specific transfusions are

successful. Caution should be used for patients who have

previously received transfusions or have had pregnancies.

What can be given in an emergency?Type O Rh-Negative (Universal Donor),

Uncrossmatched Blood Type O blood lacks the A and B antigens Type O Rh-negative, uncrossmatched packed

RBCs should be used in preference to type O Rh-negative whole blood.

More than two units of type O Rh-negative, uncrossmatched whole blood, the patient probably cannot be switched to his or her blood type .

Specific Recommended Protocol1. Infuse crystalloids or colloids.2. Draw a blood sample for typing and

crossmatching.3. If crossmatched blood is not ready to give,

use type-specific or type O Rh-negative cells or type O Rh-positive cells for males or postmenopausal females without a history of transfusions.

SummaryThe crossmatch “shall use methods that

demonstrate ABO incompatibility and clinically significant antibodies to red cell antigens

If an emergency transfusion is required after type and screen alone, an immediate-phase crossmatch is performed before transfusion (an abbreviated format )

If crossmatched blood is not ready to give, use type-specific or type O Rh-negative cells