Principles of blood transfusion Flashcards
What are agglutinins?
- they are naturally occurring complete pentameric IgM antibodies
- able to fix complement and cause haemolysis
What can occur if a transfusion is ABO incompatible? Why is it incompatible?
causes intraventricular haemolysis
- shock, hypotension, tachycardia
- renal failure, loin pain, haemoglobin
- disseminated intravascular coagulation
- death Antibodies for the red cell antigen occur naturally due to cross-reactivity with gut bacterial antigens
What is forward (cell) grouping?
A two-part test
- testing for A/B antigens
- testing the serum or plasma for ABO antibodies
What is reverse grouping (serum confirmation) ?
- testing to see what antibodies are in a persons blood
- the serum is tested with either antigen A B or O
What is entailed in compatibility testing?
- donor red blood cells suspended with recipient serum
- incubated between room temp and 37 degrees
- observed to ensure no agglutination takes place
Give examples of some other blood groups
What are atypical antibodies?
- These occur due to sensitisation with foreign red cell antigens, from either previous transfusion or by pregnancy
- can cause blood transfusion reactions to take place if the patient transfused with incompatible blood in the future
anti-globulin test
What is the Coombs test/
- uses anti-immunoglobulin antibodies to agglutinate red cells
- Teo types, Direct and Indirect, DAT/IAT
Direct anti-immunoglobulin
What does a DAT test show
Uses blood sample from the patient
- tells us if the red cells are coated with antibody
- positive after a transfusion reaction and in HDN
- positive in autoimmune haemolytic anaemia
indirect anti-immunoglobulin
What does a IAT test show?
Uses recipients serum, then donor blood is added
- a lab test for blood group antigens
- indicates if a patient is psoitive for Rhesus and other blood groups
Explain the Rhesus system
- Rh positive peopl cannot devekip antibodies
- 15% of people ar Rh negative
- Rh -ve people can devlope antibodies if they are transfused with Rh +ve blood or are pregnant with a rh +ve baby
- this is rhesus sensitisation and the antibody generated is IgG type
What is haemnolytic disease of the newborn?
- When a Rh(D) -ve mother is pregnant with an Rh positive fetus,
- greatest cause is anti-D
- she may produce antibodies (IgG) that can cross the placenta and harm the baby
- this can lead to neonatal haemolytic anaemia, fetal/ neotal jaundice and kernicterus (brian damage)
Prevention od haemolytic disease of the newborn
- ABO and Rh blood group check at 12 weeks
- Rh-ve women (15%) receive anti-D antibody i.m injection at 28 and 34 weeks to prevent sensitisation
- baby tested at birth, if Rh +ve mother recieves further anti-D until Leihauer test (foetal cells) become negative
- if already sensiised, foetus requires monitoring via trans-cranial dopplers
- may require intra-uterin transfusion if there are signs of anaemia
What is in a bag of blood
- RBC
- Buffy coat: whit cells, platelets
- Plasma: albumin, gamma globulins, coagulation factors
- wate, electrolytes, additives
How is blood selected and sorted, into its Blood compenets
Blood Bag Labelling
