Indications for Blood Transfusion

A transfusion is indicated when the benefit of correcting a specific deficit in a specific patient outweighs its risks. It is not indicated to raise a laboratory number alone, to speed recovery, to improve wound healing, to replace volume, or because a result is slightly abnormal. Over-transfusion is common, and every unnecessary unit adds risk without benefit.

Principle. The decision rests on the patient's clinical state, the speed of loss, the capacity to compensate and the available alternatives, with the laboratory value as one input.

Risk context. Risks of any transfusion include immune reactions, circulatory overload, lung injury, infection and alloimmunisation. Patients with limited cardiac reserve, renal failure, infants, older adults and those with chronic anaemia (already volume expanded) are at greatest risk of overload.

Special groups. In chronic compensated anaemia, patients may tolerate haemoglobin values that would be dangerous after acute loss. In children in malaria endemic regions, severe anaemia with decompensation is a recognised emergency indication. In pregnancy, severe anaemia close to delivery may require transfusion to reduce haemorrhage risk.

Indications for red cells.

• Acute haemorrhage with haemodynamic instability or loss of an estimated 30% or more of blood volume.

• Symptomatic anaemia with evidence of inadequate oxygen delivery: chest pain, ischaemic electrocardiogram changes, syncope, heart failure, unexplained tachycardia, hypotension unresponsive to fluids, or rising lactate.

• Haemoglobin under 7 g/dL in a stable hospitalised adult, with the cardiac and orthopaedic adjustments that apply to selected patients.

• Chronic transfusion programmes for thalassaemia major and selected sickle cell indications.

Indications for platelets. Bleeding with thrombocytopenia or platelet dysfunction, and prophylaxis in hypoproliferative thrombocytopenia or before procedures at defined counts.

Indications for plasma. Bleeding with multiple coagulation factor deficiency, massive haemorrhage as part of balanced resuscitation, thrombotic thrombocytopenic purpura (as plasma exchange replacement or infusion when exchange is unavailable), and reversal of anticoagulation only when specific agents are unavailable.

Indications for cryoprecipitate. Bleeding with fibrinogen under 1.5 g/L (under 2 g/L in obstetric haemorrhage), congenital fibrinogen deficiency, and factor XIII or von Willebrand factor replacement when concentrates are unavailable.

Non-indications.

• Volume expansion in a patient who is not bleeding.

• Raising haemoglobin to a normal value in a stable patient.

• Treating iron, vitamin B12 or folate deficiency without instability.

• A minor isolated prolongation of prothrombin time or activated partial thromboplastin time without bleeding or a planned high risk procedure.

• Prophylactic platelets for immune thrombocytopenia without life-threatening bleeding.

• Prophylactic plasma before most low risk procedures.

• Providing nutrition or protein, or enhancing wound healing.

Differential considerations. Before ordering, consider iron, vitamin B12, folate, treatment of malaria or hookworm, haemolysis control, antifibrinolytic therapy, vitamin K and surgical haemostasis.

Red flags. Haemoglobin that falls despite replacement (ongoing loss or haemolysis), transfusion requirement without an identified cause, and bleeding with normal counts and coagulation (suggest a surgical source).

Ordering one unit at a time. In a stable non-bleeding adult, transfuse a single red cell unit and reassess symptoms and haemoglobin before ordering another. In bleeding patients, use bleeding rate and haemodynamics instead.

Matching the product to the indication. Use red cells for oxygen delivery, platelets for platelet defects, plasma for multifactor deficiency and cryoprecipitate or fibrinogen concentrate for low fibrinogen.

Thresholds are conditional. Write the order with the indication, target and reassessment time, for example: one unit of red cells for haemoglobin 6.5 g/dL with symptoms, reassess haemoglobin and symptoms after completion.

Alternatives to arrange at the same time. Iron (oral or intravenous), vitamin B12 or folate, treatment of the cause, tranexamic acid in bleeding, and correction of anticoagulants with specific agents.

Special requirements. Irradiated components for defined immunosuppressed and intrauterine or neonatal exchange recipients; washed or IgA deficient products for severe recurrent allergic reactions; antigen negative red cells for patients with alloantibodies.

Monitoring. Symptoms, vital signs and the specific laboratory target at the planned time. For a non-bleeding patient, the haemoglobin response to one unit is usually about 1 g/dL in a 70 kg adult.

Complications. Circulatory overload (watch fluid balance and respiratory rate), reactions in the first 15 minutes and hours after, and delayed haemolysis days later.

Referral and escalation. Consult haematology for transfusion dependence of unclear cause, refractory anaemia, and unusual requirements. Consult the blood bank when the indication is unclear and the requested volume is large.

Disposition. Record the indication, product, dose and response. Plan cause-directed treatment so the need for further transfusion is removed.