MOD7 Pretransfusion and Compatibility Testing

mandatory tests for blood donation

• ABO/Rh and Kell → If D neg, weak D testing required on first donation

• isohemagglutinin titers (anti-a, anti-b)

• red cell antibody screen

• syphilis

• hepatitis

• HIV

• human T-cell lymphotropic virus (anti-HTLV I and II)

• west nile (NAT) from June 1 to Nov 30

blood donation from at risk donors

additional testing of:

chagas

west nile (by NAT) outside normal testing period if donor has travelled outside of CA in the 8wks prior

D typing patients

testing for weak D not necessary → giving D negative cells doesnt cause harm to patient

what has to happen prior to transfusion when XMing

donor and recipient must have two ABO/Rh typings prior to transfusion

D typing donors

if donor types D neg, must do weak D typing on their first donation

purpose of an antibody screen

to detect unexpected clinically significant red cell antibodies

3 cells: D+, D+, D-

2 cells: D+, D+

type and screen specimen retention

7 days at 1-6deg following transfusion

atleast one month from date of collection

donor segment retention

7 days at 1-6deg post transfusion

49 days from date of receipt

records of pretransfusion testing retention

minimum 5 years

records for pts who have received transfusions retention

atleast 10 years, could be indefinitely in some labs

donor records retention

10 years, some indefinitely

serological crossmatching techniques (2)

immediate spin crossmatch

antiglobulin crossmatch IAT

when are immediate spin XMs done

in date/current T&S has been done on recipient

confirmatory ABO grouping is available and completed

antibody screen on current specimen is negative

no history of clinically significant antibody

immediate spin XM purpose

only detects agglutinates due to IgM abs

used to detect ABO incompatibilities

which type of XM is done if the ab screen is positive/pt has a hx of clinically significant ab

antiglobulin crossmatch IAT XM

when can an electronic crossmatch EC/computer-assisted crossmatch CAC be performed

current T&S

confirmatory ABO type (historical or completed)

no clinically significant abs on ab screen

no hx of clinically significant abs

donor unit has had 2 ABO/Rh typings performed

electronic XM/computer assisted XM purpose

computer detects ABO incompatibilities between pt and donor unit

minimum of 2 ABO/Rh on pt from diff collections AND 2 ABO/Rh on donor unit

efficient → dont need to reserve units; TAT dec

recipients of red cells must receive

ABO compatible products

recipients of whole blood must receive

ABO identical products

donor red cells and recipient plasma must be

ABO compatible

what RBCs do Rh- premenopausal women (<45yr) receive

must receive Rh- red cells → dont want to develop anti-D

requirements for transfusion of plasma products

dont need T&S but:

no current T&S →2 hx ABO groups from different admissions

if emerg → 2 current (on this admission) ABO groups — ex current T&S and confirmatory ABO on diff occasion

examples of plasma products

octaplasma → solvent detergent S/D treated pooled plasma

plasma

cryosupernatant

cryoprecipitate

plasma products should be compatible with recipient’s

red blood cell antigens

what antigens are on platelets

ABO antigens and HLA

primary consideration → ABO naturally occurring abs present in plasma

what unit is given to an urgent/unscheduled bleeding/OR/ER

first expiring unit of any type

if bleeding out, plts arent circulating long enough to cause a reaction, theyre just used for clotting

plt choice for patient type O

1st: O

2nd: 1st expiring

3rd: N/A

plt choice for patient type A

1st: A

2nd: O

3rd: 1st expiring

plt choice for patient type B

1st: B

2nd: O

3rd: 1st expiring

plt choice for patient type AB

1st: AB

2nd: O

3rd: 1st expiring

plt choice for patient type unknown

1st: O

2nd: 1st expiring

group AB platelets

very limited supple

prioritized for pediatric use

platelets and Rh antigens

dont carry them but products usually contain some RBCs

when is RhIg given with platelets

given with first dose to Rh- recipients of Rh+ plts

prevent formation of anti-D

when are emergency O neg unmatched units provided

in an emergency situation and the physician doesnt want to wait for ABO Rh compatible blood

what is performed in cases of an emergency

STAT type and screen and crossmatch if time permits

when are group-specific unmatched units released

if we have a T&S specimen and have completed 2 ABO/Rh typings

what happens in shortage of Rh neg blood

Rh pos blood is given to males or postmenopausal women >45y/o

(most likely) wont be pregnant, so dont have to worry too much about developing anti-D antibodies

massive transfusion

infusion of volume of blood approximating the recipients total blood volume

10 or more units of red cells

what units are used to transfuse premenopausal women in cases of massive transfusion

save Rh negative red cells until the end of the episode when the pt is stabilizing → predominately Rh neg cells stay in their circulation

autologous transfusion

patient is transfused with their own blood that has been previously collected

limitations: pt must be in good health, collected blood can only be used for that pt, very expensive

directed donation

parents/guardians can donate to their children under the age of 18

can only be used for the child they were bled for

child must have current T&S and crossmatch