Immunohematology Flashcards
the study of antigens, antibodies, and their reactions, as pertaining to blood
immunohematology
the process of collecting, separating and storing blood products, and ensuring that these products are safe for therapeutic use
blood banking
what is the most frequently performed and most important test in the blood bank?
ABO grouping
blood type refers to _____ present on the RBC membrane
antigens
A and B genes correspond with A and B _____, respectively
antigens
the O gene is _____, producing no antigen
amorph
what is the mendelian genetics of A and B genes?
codominant
what is the mendelian genetics of O gene?
autosomal recessive
genetic composition inherited from parents
genotype
observable expression of the blood type
phenotype
develop after 6 months of age in response to antigens not present on the RBC membrane
ABO antibodies
blood type A has which antibodies present?
B antibodies
blood type B has which antibodies present?
A antibodies
blood type AB has which antibodies present?
no antibodies
blood type O has which antibodies present?
A and B antibodies
refers to the presence or absence of the D antigen
Rh antigens
D antigen present on RBC membrane =
Rh +
D antigen absent from RBC membrane =
Rh -
how do Rh antibodies most commonly develop?
from exposure to foreign RBC antigens through pregnancy or blood transfusion
what can occur since Rh antibodies readily cross the placenta?
hemolytic disease of the newborn (HDN)
what is the most common and most important pretransfusion test performed?
blood typing
detects in vivo coating of RBC with antibody, and identifies immune-mediated hemolytic anemia and hemolytic disease of the newborn
Direct antiglobulin/Coombs test (DAT)
detects in vitro coating of RBC with antibody, and is used for antibody screening and compatibility testing
Indirect antiglobulin/Coombs test (IAT)
what does a positive antibody screen indicate?
unexpected antibody is present and must be identified before transfusion
in which patients does a higher rate of alloimmunizations occur?
those who have received multiple transfusions
blood banker identifies the specific antibody present that is responsible for the positive screen
antibody identification
testing donor blood with patient serum for compatibility
crossmatch
what sample is a crossmatch performed on?
packed RBCs only
what is the leading cause of M&M related to blood transfusion?
clerical errors
what tube is anticoagulant blood preferred in?
EDTA (lavender)
what is required to confirm ABO?
collection of a second sample from a different time
ordered when a patient is losing blood rapidly and there is little time to complete required pretransfusion testing
crash blood
what blood type will be given to patients with unknown BT history?
O
RBC separated from whole blood through centrifugation and suspended in residual plasma and additive solution (preservatives and nutrients)
packed RBCs
used in immunocompromised patients
leukocyte-reduced packed RBCs
PRBCs are treated with gamma radiation to prevent T lymphocyte activation; used for immunocompromised patients
irradiated PRBCs
occurs when viable T lymphocytes are transplanted into an immune compromised patient and mounts an immune response due to differences between donor and recipient HLA antigens
graft-vs-host disease (GVHD)
removes plasma proteins, which are responsible for most allergic reactions; also removes WBCs and platelets
washed PRBCs
which blood product is indicated for patients with a history of severe allergic transfusion reactions?
washed PRBCs
contains all blood components and indicated for anemia and emergency traumas
whole blood
what makes whole blood safe to use in emergencies?
low titer (limited A and B antibodies)
what patients are platelets not indicated for?
patients with PLTs less than 1,000
indicated to treat nonspecific coagulation deficiency in bleeding patients with liver failure, DIC, vit K deficiency, warfarin overdose, or in a massive transfusion protocol
fresh frozen plasma
concentrate of fibrinogen, factors VIII, XIII, vWF, and fibronectin
cryoprecipitate
what is cryoprecipitate primarily used in?
fibrinogen deficiency
what antigens are present on lymphocytes?
HLA and MHC antigens
how are HLA genes inherited?
one from each parent
what test is important in determining organ transplant compatibility?
HLA testing
destruction of transfused RBCs due to antibody-mediated incompatibility
acute hemolytic transfusion reaction
a patient presents with fever, chills, hypotension, pain at infusion site/ flanks/ chest/ or abdomen. what are they likely experiencing?
acute hemolytic transfusion reaction
when does acute hemolytic transfusion reaction occur?
less than 24 hrs after transfusion
what can acute hemolytic transfusion reaction lead to?
acute kidney injury
positive DAT 24 hours to 28 days after a transfusion, with newly identified alloantibody, and evidence of hemolysis
delayed hemolytic transfusion reaction
a patient presents with acute respiratory distress (dyspnea, tachypnea, and hypoxemia). what could it be?
transfusion-related acute lung injury (TRALI)
when must TRALI occur?
within 6 hours of transfusion
what would a radiograph of TRALI show?
bilateral pulmonary edema
the presence of 3 or more signs of fluid overload occurring within 6 hours of transfusion
transfusion-associated circulatory overload (TACO)
a patient presents with acute respiratory failure from pulmonary edema due ton increased intravascular tone. what is this?
TACO (transfusion-associated circulatory overload)
a patient presents with fever >100.4 F / a change >1.8 F from pretransfusion temp occurring during or within 4 hours of the transfusion
febrile nonhemolytic transfusion reaction
what is
febrile nonhemolytic transfusion reaction
related to?
product storage time
what is the most common reaction seen with platelet and plasma transfusions?
allergic transfusion reactions (ATR)
a patient presents with hives, urticaria, and no fever. what is this?
allergic transfusion reaction (ATR)
what are 2 reasons transfusion-associated graft vs host disease can occur?
- recipient is immunocompromised
- partial HLA matching in WBCs (relatives)
what procedure can be done to confirm transfusion-associated graft vs host disease?
tissue biopsy
severe and sudden drop in platelet count occurring 5-10 days after transfusion; patient has counts <10 and bleeding of mucous membranes
post-transfusion purpura
what is the treatment for post-transfusion purpura?
steroids
IV immunoglobulins
what should a patient with a known history of post-transfusion purpura be given?
washed units
what is the first step if any transfusion reaction is suspected?
stop the transfusion immediately
an individual donates blood for their own use
autologous donation
in what procedure is autologous donation, in which blood is collected intraoperatively and returned to circulation, common in?
cardiac procedures
blood is collected for transfusion to a known recipient
directed donation
blood withdrawal performed as treatment for a medical condition
therapeutic phlebotomy
process in which a donor or patient’s whole blood is removed, separated into components, the desired component is collected and recombined components are returned to circulation
hemapheresis
the destruction of fetal or neonatal RBCs by maternal antibodies
hemolytic disease of newborn (HDN)
fetal hematopoietic tissue increases production of RBCs to compensate for reduced fetal RBC survival in HDN
erythroblastosis
in unable to compensate for HDN, severe anemia develops with subsequent high output cardiac failure and intrauterine death. what is this called?
hydrops fetalis
what is administered to Rh- mothers at 28 weeks and after birth to reduce Rh HDN?
rhogam
condition due to anti-A or anti-B in type O mothers
ABO HDN
what is the leading cause of HDN?
ABO incompatibility
what blood type in mother and neonate most commonly leads to ABO incompatibility?
type O mothers with type A, B, or AB neonates
