Blood groups and Blood transfusion Flashcards
What are red cell antigens?
Proteins on the surface of red blood cells; 26 blood group systems exist, with ABO and Rhesus being the most important.
What genes are involved in the ABO blood group?
FUT1 and FUT2 (chromosome 19) code for H substance; A and B genes (chromosome 9) code for glucosyl transferases.
What antibodies are naturally found in people without A or B antigens?
Naturally occurring IgM anti-A and/or anti-B antibodies.
What antigens make up the Rhesus system?
c, C, D, e, and E antigens, coded on chromosome 1 and inherited as a triplet.
What does Rhesus negative mean?
It implies absence of the D antigen.
Are Rhesus antibodies naturally occurring?
No, they develop after exposure through pregnancy or transfusion.
What is a transfusion reaction?
An immune response against transfused blood components.
What causes acute haemolytic transfusion reactions?
Pre-existing antibodies reacting to mismatched blood, especially ABO incompatibility.
What causes delayed haemolytic reactions?
New antibodies formed after transfusion, leading to red cell breakdown days later.
What are allergic transfusion reactions?
Responses to drugs or plasma proteins, causing urticaria or anaphylaxis.
What causes febrile non-haemolytic reactions?
Antibodies to white blood cell antigens (HLA).
How are acute transfusion reactions managed?
Stop transfusion, assess patient, send blood to lab, give IV fluids, monitor urine and renal function.
What is cross-matching?
Testing recipient’s plasma against donor red cells to check for agglutination.
Why is cross-matching important?
To prevent transfusion reactions by ensuring blood compatibility.
What is screened in donor blood?
ABO, Rhesus D, other antigens, and infections like HIV, Hep B/C, syphilis.
What is screened in recipient blood?
ABO, Rhesus D, and antibodies against a panel of red cell antigens
What are the effects of HDN?
Anaemia, jaundice, brain damage, or foetal death.
How is Rhesus D sensitisation prevented?
Anti-D prophylaxis for D-negative mothers at 28 and 40 weeks and after obstetric events.
What is the Kleihauer test?
Detects foetal cells in maternal circulation by acid elution of fetal hemoglobin.
How is the foetus monitored for anaemia?
Ultrasound for cerebral artery flow, ascites, liver/spleen size, and umbilical cord sampling.
How is HDN managed after birth?
ssess clinically, test blood, use phototherapy, and consider transfusion.
What are plasma-reduced red cells used for?
Haematological underproduction, trauma, GI bleeding, childbirth, surgery.
What are platelets used for?
Marrow failure, massive haemorrhage
What is fresh frozen plasma used for?
Liver failure, massive haemorrhage.
