27th May 2023

Haemolytic reactions

Acute haemolytic reaction

In ABO-incompatible red cell transfusion, a patient’s anti-A or anti-B antibodies cause rapid haemolysis of the transfused red cells and inflammatory cytokine release. Shock, acute renal failure and disseminated intravascular coagulation (DIC) may occur. ABO-incompatible red cell transfusion is almost universally fatal. Stringent safety checks when taking G&S samples, transporting blood products and carrying out blood product administration aim to avoid this ‘never event’. Patients become very unwell within minutes of transfusion with flushing, abdominal pain, a sense of impending doom, tachycardia, hypotension and may have signs of bleeding from needle wounds.

Delayed haemolytic transfusion reaction

Delayed haemolytic transfusion reactions (DHTR) can occur 1-14 days after transfusion in a patient who has been previously alloimmunised to a red cell antigen by blood transfusion or pregnancy.  This alloantibody may have fallen to an undetectable level and therefore may not be identified on the G&S antibody screen. DHTR should be suspected if the following occur:

• A falling haemoglobin/failure to increment
• Jaundice
• Fever
• Haemoglobinuria

A haemolysis screen should be performed. Treatment is supportive, but the antibody history must be recorded by the laboratory.

Post-transfusion purpura

A significant fall in platelet count can occur 5-12 days after blood product transfusion. This reaction is caused by previous alloimmunisation to a platelet antigen by transfusion or pregnancy. Treatment is supportive, but if the patient has life-threatening bleeding, then IVIG should be administered.