Pathology
Blood Banking and Transfusion
Blood banking and transfusion for MBBS and NEET-PG: ABO and Rh systems, compatibility testing, Coombs tests, blood components, transfusion reactions and transmitted infections, mapped to NMC codes PA22.1 to PA22.7.
MedNext Academy | 3 min read
Blood Banking and Transfusion
Blood banking and transfusion for MBBS and NEET-PG: ABO and Rh systems, compatibility testing, Coombs tests, blood components, transfusion reactions and transmitted infections, mapped to NMC codes PA22.1 to PA22.7.
This chapter covers transfusion medicine. It sets out the ABO and Rh blood group systems, the principles of compatibility testing and the Coombs tests, the blood components and their uses, and the transfusion reactions and transfusion-transmitted infections that make safe practice essential.
High-yield: Blood Banking and Transfusion
- The ABO system is the most important blood group system, and ABO incompatibility causes severe intravascular haemolysis.
- Group O individuals are universal red cell donors, and group AB individuals are universal red cell recipients.
- The Rh system centres on the D antigen; a Rh-negative mother can be sensitised to a Rh-positive fetus.
- Haemolytic disease of the newborn results from maternal antibodies against fetal red cell antigens, chiefly Rh D.
- Anti-D immunoglobulin given to Rh-negative mothers prevents sensitisation and haemolytic disease of the newborn.
- Cross-matching tests donor red cells against recipient serum to confirm compatibility before transfusion.
- The direct Coombs test detects antibody already bound to red cells, as in haemolytic disease of the newborn and autoimmune haemolysis.
- The indirect Coombs test detects antibody free in the serum and is used in cross-matching and antibody screening.
- Packed red cells raise oxygen-carrying capacity; platelets treat thrombocytopenic bleeding; fresh frozen plasma replaces clotting factors.
- Cryoprecipitate is rich in fibrinogen, factor VIII and von Willebrand factor.
- An acute haemolytic transfusion reaction, usually from ABO mismatch, causes fever, loin pain, hypotension and haemoglobinuria.
- A febrile non-haemolytic reaction is the most common transfusion reaction and is due to recipient antibodies against donor white cells.
- Transfusion-transmitted infections include hepatitis B, hepatitis C, HIV, malaria and syphilis, and mandatory screening reduces the risk.
- Massive transfusion can cause hypocalcaemia (from citrate), hyperkalaemia and coagulopathy.
Blood components and their uses
- **Packed red cells:** Raise oxygen-carrying capacity in symptomatic anaemia.
- **Platelets:** Treat or prevent bleeding in thrombocytopenia.
- **Fresh frozen plasma:** Replace multiple clotting factors, as in DIC or warfarin reversal.
- **Cryoprecipitate:** Rich in fibrinogen, factor VIII and von Willebrand factor.
NMC competencies in this chapter
- **PA22.1:** Blood group systems (ABO and Rh)
- **PA22.2:** Indications, principles and steps of compatibility testing
- **PA22.3:** Blood grouping, cross-matching and the indirect Coombs test
- **PA22.4:** Blood components and their clinical uses
- **PA22.5:** Infections transmitted by blood transfusion
- **PA22.6:** Transfusion reactions and the investigation of a transfusion reaction
- **PA22.7:** Indications, principles and procedure of autologous transfusion
Frequently Asked Questions
Why is the ABO system so important in transfusion?
Because ABO incompatibility triggers a severe acute intravascular haemolytic reaction that can be fatal, so ABO matching is fundamental to safe transfusion.
What is the difference between the direct and indirect Coombs tests?
The direct Coombs test detects antibody already bound to red cells, while the indirect Coombs test detects free antibody in the serum, used in cross-matching.
What is the most common transfusion reaction?
The febrile non-haemolytic reaction, caused by recipient antibodies against donor white cells, which produces fever without haemolysis.
How is haemolytic disease of the newborn prevented?
By giving anti-D immunoglobulin to Rh-negative mothers, which prevents them from being sensitised to the Rh D antigen of a Rh-positive fetus.
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