Complications of Blood Transfusions

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Last updated: May 18, 2020
Revisions: 15

Last updated: May 18, 2020
Revisions: 15

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A blood product is any part of the blood that is collected from a donor for use in a blood transfusion.

In this article, we shall look at the complications of blood transfusions, both general complications and transfusion-specific complications.

General Complications

These are complications of packed red cell transfusions, and become progressively more likely with increasing transfusion volume.

Clotting Abnormalities

Fig 1 - Consider the use of fresh frozen plasma after 4 units of blood.

Figure 1 – Consider the use of fresh frozen plasma after 4 units of blood

Clotting abnormalities can occur due to a dilution effect, as the packed red cells transfused do not contain any platelets or clotting factors. Specific conditions like trauma also in themselves can cause coagulopathy.

To reduce the risk of any clotting impairment, fresh frozen plasma and platelets should be administered concurrently, typically done for patients receiving more than 4 units RBCs*.

*Transfusion guidelines will vary between hospitals and are usually detailed within in the Massive Transfusion Protocol

Electrolyte Abnormalities

There are two main electrolyte abnormalities that can occur in blood transfusions:

  • Hypocalcaemia  Chelation of calcium by the calcium binding agent in the preservative results in a reduced serum calcium level
  • Hyperkalaemia – Due to the (inevitable) partial haemolysis of the red blood cells and the resultant release of intracellular potassium


As blood products are thawed from frozen and then kept at cool temperatures, they may not be up to body temperature by time of transfusion, especially in a major haemorrhage protocol scenario.

Rapid transfusion of these products can lead to a drop in the patient’s core temperature, hence regular monitoring of core body temperature is always required during a blood product transfusion.

Transfusion-Specific Complications

The transfusion-specific complications can be divided into acute and delayed complications. Acute transfusion complications typically occur soon after the transfusion has been started. 

Acute Transfusion Complications

Acute Haemolytic Reaction

Acute haemolytic reaction (ABO Incompatibility) is a serious reaction caused by transfusion of the incorrect blood type, the most common cause being ABO blood group incompatibility. Donor red blood cells are destroyed by the recipient’s preformed antibodies, resulting in haemolysis.

Patients will present with urticaria, hypotension, and fever, and may have evidence of haemoglobinuria from the rapid haemolysis. Blood tests will show a reduced Hb, a low serum haptoglobin, and high LDH and bilirubin; a positive Direct Antiglobulin Test (DAT) will confirm the diagnosis.

Urgently inform blood bank that you suspect this has happened, as they may have dispensed further incorrect blood. Stop the transfusion and begin supportive measures, with fluid resuscitation and Osupplementation. Seek specialist advice for further management.

Fig 2 - The ABO blood groups. Giving a patient an incompatible blood product can result in an acute haemolytic reaction.

Figure 2 – The ABO blood groups. Giving a patient an incompatible blood product can result in an acute haemolytic reaction.

Transfusion Associated Circulatory Overload

Transfusion Associated Circulatory Overload (TACO) presents with dyspnoea and features of fluid overload. This is often a common problem in those who are already overloaded, such as those with cardiac failure.

Obtain an urgent chest radiograph, and for those whose diagnosis is confirmed, treatment is via oxygen and diuretic therapy.

Patients at risk of overload (and not as part of resuscitation or inacute haemorrhage) can be prescribed 20mg furosemide prophylactically during the transfusion to prevent this.

Transfusion Related Acute Lung Injury (TRALI)

This is a form of Acute Respiratory Distress Syndrome (ARDS), a non-cardiogenic cause of pulmonary oedema. Patients are dyspnoeic and have features of pulmonary oedema on clinical examination.

These patients have a high mortality.  Start patients on high flow oxygen and obtain an urgent chest radiograph (Fig. 3), getting specialist and intensive care input urgently.

Other Complications

  • Mild Allergic Reaction – The patient will complain of pruritus (itching). Treatment is with an anti-histamine such as chlorphenamine. Often the transfusion can be continued, however the patient should be kept under close observation.
  • Non-Haemolytic Febrile Reactions  An unpleasant, but usually non-life threatening reaction found in 1-2% of patients. The transfusion should be stopped and the patient given antipyretics (e.g. paracetamol) and anti-histamines (e.g. chlorphenamine).
  • Anaphylaxis – Presents with hypotension in the presence of anaphylactic symptoms. Stop the transfusion and treat as you would normally for anaphylaxis.
  • Infective / Bacterial Shock Hypotension without clinical signs of anaphylaxis is suggestive of infective shock (or ABO incompatibility, as described above). Stop the transfusion and perform basic resuscitation measures. Take blood cultures, start IV antibiotics, and seek immediate senior help.
Fig 3 - Chest x-ray findings (a) Transfusion related acute lung injury (b) After treatment with ventilatory support.

Figure 3 – Chest radiograph findings (a) transfusion-related acute lung injury (b) after treatment with ventilatory support

Delayed Transfusion Complications

  • Infection – There is a theoretical risk of developing any of Hepatitis B, Hepatitis C, HIV, syphilis, malaria, or vCJD with any blood transfusion. Fortunately, these are less of a concern in recent years due to screening of blood donors
  • Graft vs. Host Disease (GvHD) – GvHD occurs due to an HLA-mismatch between donor and recipient. It is most common in the transfusion of non-irradiated blood products to an immunocompromised recipient. Clinical features include a fever, skin involvement (ranging from macropapular rash to toxic epidermal necrolysis) and diarrhoea and vomiting.
  • Iron overload – Most common in patients that receive repeated transfusions, such as in thalassaemia. Multiple organs will be affected, including liver (developing liver cirrhosis), pancreas (onset of diabetes mellitus, often termed “Bronze Diabetes”), heart (developing cardiomegaly and conduction disturbances), joints (resulting in arthralgia), and skin (resulting in hyperpigmentation)