Transfusion Statements: Identifying the False Statement
Statement D, "Rh blood group antigens must be matched prior to transfusions," is false. While ABO compatibility is essential for transfusions, Rh matching is not always required, particularly in emergency situations.
Analysis of Each Statement
A. ABO compatibility is almost always needed for a successful renal transplant
- This statement is true. ABO compatibility is critical for successful renal transplantation.
- ABO incompatibility can lead to hyperacute rejection of the transplanted kidney due to preformed antibodies against donor blood group antigens 1.
- While some centers perform ABO-incompatible transplants using special protocols (plasmapheresis, immunoadsorption, rituximab), these are exceptions requiring extensive preparation, and ABO compatibility remains the standard requirement.
B. Citrate toxicity can cause hypocalcemia
- This statement is true. Blood products are stored with citrate as an anticoagulant.
- Citrate binds calcium, and during massive transfusions, this can lead to hypocalcemia 2.
- Symptoms of citrate toxicity include paresthesias, muscle cramps, hypotension, and cardiac arrhythmias due to the resulting hypocalcemia.
C. Febrile reactions may be due to bacterial contamination
- This statement is true. Febrile non-hemolytic transfusion reactions can occur due to various causes, including bacterial contamination of blood products 2.
- While most febrile reactions are due to cytokines or recipient antibodies against donor leukocytes, bacterial contamination is a serious cause that must be considered, especially with severe reactions.
- Modern leukoreduction has reduced but not eliminated these reactions 1.
D. Rh blood group antigens must be matched prior to transfusions
- This statement is false. While Rh matching is preferred when possible, it is not mandatory for all transfusions.
- In emergency situations with unknown blood type, O Rh-positive blood can be given to males and postmenopausal females 2.
- The British Journal of Anaesthesia guidelines explicitly state: "In an emergency, premenopausal females whose blood group is unknown should be given O Rh(D) negative red cells... It is acceptable to give O Rh(D) positive cells to males and postmenopausal females of unknown blood group" 2.
- A study in The Lancet Haematology demonstrated that transfusing O Rh-positive blood to emergency patients with unknown blood type carries a low risk (3-6%) of anti-D antibody formation 3.
Important Considerations in Transfusion Practice
Emergency Transfusion Protocols
- In life-threatening emergencies, the priority is providing blood quickly
- O-negative blood is reserved primarily for women of childbearing potential with unknown blood type
- Males and postmenopausal women can safely receive O-positive blood in emergencies 2, 3
Transfusion Thresholds
- Restrictive transfusion strategies (hemoglobin threshold of 7 g/dL) are recommended for most hemodynamically stable patients 2, 1
- Higher thresholds (8-9 g/dL) may be appropriate for patients with acute coronary syndrome or cardiovascular disease 2, 1
- Single-unit transfusions with reassessment are preferred over automatic multi-unit orders 1
Prevention of Transfusion Reactions
- Proper patient identification and specimen labeling are critical
- Monitoring for reactions during transfusion is essential
- Leukoreduction has reduced but not eliminated febrile reactions 1
- Complete transfusion within 4 hours of removing blood from storage 1
In conclusion, while ABO compatibility, awareness of citrate toxicity, and recognition of febrile reactions are all important aspects of transfusion medicine, the statement that Rh matching is mandatory for all transfusions is false, as evidenced by established emergency transfusion protocols.