ABO system
- Consists of three allelic genes - A, B and O
- A and B genes control synthesis of enzymes that add carbohydrate residues to cell surface glycoproteins
- The O gene is an amorph and does not transform the glycoprotein
- Six possible genotypes but only four phenotypes
- Naturally occurring antibodies are found in the serum of those lacking the corresponding antigen.
ABO blood group system
| Phenotype |
Genotype |
Antigens |
Antibodies |
Frequency (%) |
| O |
OO |
O |
Anti-A, Anti-B |
46 |
| A |
AA or AO |
A |
Anti-B |
42 |
| B |
BB or BO |
B |
Anti-A |
9 |
| AB |
AB |
AB |
None |
3 |
- Blood group O = universal donor
- Blood group AB = universal recipient
Rhesus system
- Rhesus antibodies are immune antibodies requiring exposure during transfusion or pregnancy
- 85% population are rhesus positive
- 90% of Rh-negative patients transfused with Rh-positive blood develop anti-D antibodies
Cross Matching
Blood grouping
- Patients red cells grouped for ABO and Rhesus antigens
- Serum tested to confirm patients ABO group
Antibody screening
- Detects atypical red cell antibodies in recipients serum
Crossmatching
- Tests donor red cells against patients serum
Blood products
- Whole blood
- Packed red cells
- Granulocyte concentrates
- Platelet concentrates
- Human plasma - fresh frozen plasma / freeze-dried plasma
- Plasma protein fraction
- Human albumin 25%
- Cryoprecipitate
- Clotting factors - Factor VIII / IX
- Immunoglobulins
Complications of blood transfusion
Early
- Haemolytic reactions (immediate or delayed)
- Bacterial infections from contamination
- Allergic reactions to white cells or platelets
- Pyogenic reactions
- Circulatory overload
- Air embolism
- Thrombophlebitis
- Citrate toxicity
- Hyperkalaemia
- Clotting abnormalities
Late
- Infection - cytomegalovirus / hepatitis
- Immune sensitisation
- Iron overload
Acute haemolytic or bacterial transfusion reactions
- Due to acute haemolysis or bacterial contamination
- Difficult to differentiate on clinical grounds
- May occur after infusion of small volume of incompatible or infected blood
- Associated with high morbidity and mortality
- In unconscious patient bleeding due to DIC may be only sign
- Most ABO mismatched transfusions are due to human error
- Usually occurs soon after start of transfusion
- Patient feels unwell and agitated
- Symptoms include back pain and pain at infusion site
- Associated with shortness of breath, rigors
- Examination will show hypotension, oliguria and bleeding from venepuncture sites
- Urinalysis will show haemoglobinuria
Management
- Discontinue transfusion immediately and remove giving set
- Check unit of blood against patients identity
- Give intravenous crystalloid
- Consider transfer to the intensive care unit
- Take blood for FBC, plasma haemoglobin, clotting, blood cultures and repeat grouping
- Give broad spectrum antibiotics
- Monitor urine output and ECG
Anaphylaxis
- Usually occurs soon after start of transfusion
- May be seen in IgA deficient patients reacting to transfused IgA
- Presents with circulatory collapse and bronchospasm
Management
- Discontinue transfusion and remove giving set
- Maintain airway and give oxygen
- Administer adrenaline, chlorpheniramine, salbutamol
- If the patient is IgA deficient any further transfusion must be carefully planned
Non-haemolytic transfusion febrile reaction
- Usually occurs more than 30 minutes after start of transfusion
- Patient feels generally well but may be shivering
- Temperature is usually less than 38.5 °C
- Blood pressure is usually normal
Management
- Stop transfusion and assess possibility that this may be a more significant reaction
- Restart transfusion at a slower rate
- Consider the use of paracetamol
- Hydrocortisone should not be routinely used during a transfusion
Transfusion related acute lung injury
- Occurs following administration of plasma-containing blood components
- Due to interaction of donor antibodies with recipient white cells
- The clinical pictures is similar to ARDS
- Occurs 30 minutes to several days after transfusion
- Clinical features include fever, cough and shortness of breath
- Chest x-ray shows perihilar shadowing
- Treat as ARDS
Delayed haemolytic transfusion reaction
- Occurs 5-10 days after transfusion
- Clinical features are usually minimal
- Possibly unexplained pyrexia or jaundice
- Unexplained drop in haemoglobin
- Urinalysis shows urobilinogenuria
Management
- Check LFTs, clotting and red cell antibody screen
Autologous transfusion
- Is the use of the patients own blood
- Particularly useful in elective surgery
- Accounts for 5% of transfusions in USA
- Reduces the need for allogeneic blood transfusion
- Reduces risk of postoperative complications (e.g. infection, tumour recurrence)
- Three main techniques are:
- Predeposit transfusion
- Intraoperative acute normovolaemic haemodilution
- Intraoperative cell salvage
Predeposit transfusion
- Blood collection begins 3-5 weeks preoperatively
- Between 2 and 4 units are often stored
- Last unit collected more than 72 hours preoperatively
- Eliminates the risk of viral transmission
- Reduces the risk of immunological transfusion reactions
- Reduces risk of postoperative immunosuppression seen with allogeneic transfusion
- Collection is expensive and time-consuming
- Only suitable for elective surgery
Intraoperative acute normovolaemic haemodilution
- Whole blood is removed at start of operative procedure
- Between 1.0 and 1.5 litres can be collected
- Replaced with crystalloid or colloid solution
- Few detrimental effects of acute anaemia have been demonstrated
- Blood is stored in theatre at room temperature
- Blood is re-infused during or immediately following surgery
- Cheaper than predeposit transfusion
- Little risk of administrative or clerical error
- Suitable for elective or emergency surgery at which considerable blood loss anticipated
Intraoperative cell salvage
- Shed blood is collected from operative field
- Blood is anticoagulated with citrate or heparin and filtered to remove debris and clots
- Cells are then washed with saline and concentrated by centrifugation
- Concentrate is then reinfused
- Large volumes of blood can be salvaged
- Salvaged blood is not haemostatically intact
- Platelets and clotting factors are consumed
- Suitable in cardiac or trauma surgery
- Contraindicated in contaminated operative fields and in the presence of malignancy
Bibliography
Regan F, Taylor C. Blood transfusion medicine. Br Med J 2002; 325: 143-147.
Sloop G D, Friedberg R C. Complications
of blood transfusion. How to recognise and respond to
non-infectious reactions. Postgrad Med 1995; 98:
159-162.
Vanderlinde E S, Heal J M, Blumberg N. Autologous transfusion. Br Med J 2002;
324: 772-775.
Winkelstein A, Kiss J E. Immunohematologic
diseases. JAMA 1997; 278:
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