Haemolysis

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► Acute intravascular haemolysis

► Delayed (usually extravascular haemolysis)

Acute intravascular haemolysis

When to suspect this adverse reaction?

It characteristically begins with an increase in temperature and pulse rate.

Symptoms may include chills, rigors, dyspnoea, chest and/or flank pain, discomfort at infusion site, abnormal bleeding or shock. Instability of blood pressure is frequently seen.

Transfused patients develop oliguria, haemoglobinuria and haemoglobinaemia.

In anaesthetised patients, hypotension and evidence of disseminated intravascular coagulation (DIC) may be the first sign.

Usual causes?

There is immunologic destruction of transfused red cells, due to incompatibility of antigen on transfused cells with antibody in the recipient circulation.

The most common cause is transfusion of ABO-incompatible blood.

It is rarely due to physical or chemical damage to transfused red cells; for example, effects of drugs co-administered with transfusion, effects of bacterial toxins, thermal injury due to freezing or overheating or transfusion of red cell antibodies.

Investigation

Clinically assess patients for common features of haemolysis occurring within 4 hours of transfusion. Check clerical records, such as ABO typing of patient and unit.

Perform Direct Antiglobulin Test (DAT) and Indirect Antiglobulin Test (IAT), renal function, and tests for haemolysis (urinary haemosiderin, serum haptoglobulin and so on).

What to do?

Stop transfusion immediately and follow other steps for managing suspected transfusion reactions. Seek urgent medical assistance.

Maintain blood pressure and renal output. Induce diuresis with intravenous fluids and diuretics.

This may become a medical emergency so support blood pressure and maintain an open airway.

Do not administer additional blood packs until cleared by haematologist or Transfusion Service Provider.

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Delayed (usually extravascular) haemolysis

When to suspect this adverse reaction?

This reaction usually develops in 2 to 14 days after transfusion.

Patients may present with unexplained fever, positive Direct Antiglobulin Test (DAT), jaundice and unexplained decrease in haemoglobin.

It occurs in 1:2,500 to 1:11,000 of transfusions.

Usual cause?

Previously red cell alloimmunised patients in whom antigens on transfused red cells provoke anamnestic production of red cell antibody.

Investigation

Request for Direct Antiglobulin Test (DAT), Indirect Antiglobulin Test (IAT), liver function tests and markers of haemolysis (urinary haemosiderin, serum haptoglobin, and so on).

What to do?

Most delayed haemolytic reactions have a benign course and require no treatment.

If an antibody is identified, you may request for antigen-negative blood if further transfusion is needed.

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Reference

Roback JD (ed). Non-infectious complications of blood transfusion. Chapter 27, AABB Technical Manual, 17th edition. AABB Press, Bethesda, 2011.