Transfusion Biology Flashcards
Define blood group antigen
carb/protein present on surface of an RBC
Define RBC phenotype
combo of antigens on RBC surface
Define RBC genotype
genetic sequences at the loci for blood group antigens
Who is a universal recipient of blood
AB+
Who is a universal donor of blood
O-
Describe the presence or absence of Rh D antigen
- Rh+ if it is present (Can receive Rh+ OR Rh- blood)
- Rh- if it is not present (Can ONLY receive Rh- blood)
When is an anti-D alloantibody produced
When an Rh- person is exposed to small amounts of Rh+ cells (transfusion, pregnancy)
Describe the Bombay blood group
Can’t receive blood from A, AB, B, or O and ONLY from Bombay group
(can still donate blood)
Describe pre-transfusion testing
- ABO/Rh(D) typing: determines presence/absence of A, B, and Rh antigens on the patients RBCs
- Antibody screen: screens antibodies in plasma, done on everyone
- Compatibility testing/crossmatch: done when there is a high probability that the pt will need a transfusion & makes sure donor blood is compatible
Describe forward typing in ABO/Rh typing
test the patients RBCs for presence of A, B, and D antigens using antisera
Describe reverse typing in ABO/Rh typing
testing patients serum for presence of Anti-A, Anti-B, and Anti-D antibodies
Describe antibody screening by IAT (indirect antiglobulin test)
test for antibodies to common clinically significant RBC antigens
NOT a compatibility test, other Abs aside from ABO & Rh
What does a direct antiglobulin test screen for (DAT, Coombs)
used to detect Abs and/or complement on the surfaces of RBCs
- used in hemolytic anemia to detect auto/alloantibodies
What does an indirect antiglobulin test screen for (IAT, Coombs)
used to detect allo/autoantibodies in plasma or serum
- used in antibody screening for every pregnancy & compatibility testing before transfusion
If a crossmatch is negative, does that mean the blood product is compatible or incompatible with the patient?
compatible
Describe the 3 steps of pre-transfusion testing
- type (forward & reverse blood typing)
- screen (for antibodies)
- cross (identifying compatible blood product)
When is a type and screen done vs a type and cross
Type and screen
- just in case surgery is needed (minor surgery)
- doesn’t involve finding a compatible product
Type and cross
- transfusion likely needed or is needed (major surgery, trauma)
- does identify a compatible blood product
What special populations may be at greater risk when it comes to transfusion reactions
- infants <4 mos
- pregnancy
- sickle cell disease (w/ frequent transfusion hx)
- stem cell or organ transplant recipients
What non-antibody screening is done on blood products
Infectious agents
- HBV, HBC
- HIV
- Treponema pallidum
- Covid-19 Abs
- etc.
What are the major indications for packed RBCs (PRBCs)
- symptomatic anemia including acute blood loss (Hgb <8)
- asymptomatic w/ Hgb <7
- exchange transfusion in sickle cell pain crisis or hemolytic disease of a newborn
What do PRBCs do for us
- provide RBC mass and increase oxygen carrying capacity in the blood
What is the downside of transfusing whole blood
- must be stored at 4C
- platelet dysfunction over time
- coag factors degrade over time
- decreased capacity to deliver O2 over time
Describe the indications for platelet transfusion
- thrombocytopenia or plt dysfunction (<10k or <50k prior to procedure)
What does a platelet transfusion do
- reduces incidence of bleeding
- provides functionally active platelets for pts with platelet dysfunction
- 2 unites of Plts can increase the count by appx 10k
What is in fresh frozen plasma and what does it do when transfused
- contains all coag factors (except fV and fVIII) and all plasma proteins (except albumin, protein C & S)
- helps control bleeding
What are the indications for fresh frozen plasma transfusion
- correction of coagulopathies (rapid reversal of warfarin in major bleeding)
- treatment of TTP
- massive transfusion protocol
(Rh type not a consideration)
Who is the universal donor and universal recipient for plasma
Universal donor: AB
Universal recipient: O
Who is the universal donor and universal recipient for RBCs
Universal donor: O
Universal recipient: AB
What is in cryoprecipitate and what does it do
- contains plasma proteins, fibrinogen, Factor VIII, Factor XIII, vWF
- raises fibrinogen level ~100mg to help aid hemostasis
What are the indications for cryoprecipitate infusion
- fibrinogen deficiency (Disseminated Intravascular Coagulation, liver disease, VWD)
- massive transfusion protocol
When would cryoprecipitate be ineffective?
- thrombocytopenic bleeding (requires platelets)
- reversal of anticoagulation (does not have vit-K dependent factors - requires FFP)
Describe leukoreduction of blood products
- removal of leukocytes via filtration/washing from PRBCs or platelets
- prevents CMV infection, fever, alloimmunization
(done to most blood products prior to storage)
Who requires leukoreduced blood products?
transplant patients & someone who requires multiple platelet transfusions
Describe irradiated RBCs
Prevents transfusion associated graft vs host disease (TAGVHD)
- shortens half life of RBCs
- used for immunosuppressed recipients
Describe washing of blood products
removes plasma/supernatant in PRBCs & platelets
- red cells only live 24hrs, platelets 4hrs
- indicated in IgA deficiency, neonatal thrombocytopenic purpura, hx severe allergy to transfusion, sensitive to K+
Describe volume reduction of blood products (platelets)
removes excess donor plasma
- indicated in pts sensitive to volume overload or when ABO incompatible platelets transfused
Describe apheresis of a blood product
removal of a targeted cell type or substance in the blood while maintaining isovolemia
- plasmapheresis
- cytapheresis
- photopheresis
What does plasmapheresis remove
plasma including autoantibodies, immune complexes, protein bound toxins
What does leukocytapheresis remove
malignant WBCs in pts with leukemia
What does erythrocytapheresis treat
severe sickle cell, malaria treatment, babiosis
What does photopheresis do
separates leukocytes from whole blood & exposes to light
What is the most common transfusion complication
HLA allosensitization
Less common: infection
Extremely rare: graft vs host disease
B
A
TACO & TRALI
(if no fever: TACO)
What are 2 RBC breakdown products that can be detected int he setting of acute hemolytic transfusion reactions
LDH & bilirubin
which electrolyte leaks from blood during storage
potassium
Describe the etiology & presentation of urticarial transfusion reactions
Describe the etiology & presentation of febrile non-hemolytic transfusion reactions
Describe the etiology & presentation of transfusion associated circulatory overload
CXR with bilat infiltrates
Describe the etiology & presentation of transfusion related acute lung injury (TRALI)
Describe the etiology & presentation of acute hemolytic transfusion reaction
Describe the etiology & presentation of transfusion associated graft vs host disease
