Severity and imputability of transfusion reactions are assessed according the levels defined by the International Society of Blood Transfusion and International Haemovigilance Network.


Nonhemolytic transfusion reaction (NHTR)

Rise in temperature of ≥ 2oC (with or without rigors/chills) during or in the first two hours after a transfusion, with normalisation within 24 hours after the transfusion, OR rigors/chills within the same time limits, without other relevant symptoms or signs.

Mild (nonhemolytic) febrile reaction

Rise in temperature ≥1°C (<2°C) during or in the first two hours after a transfusion with normalisation within 24 hours after the transfusion, without other relevant symptoms or signs.

Acute hemolytic transfusion reaction

Signs or symptoms of hemolysis occurring within a few minutes of commencement or until 24 hours after a transfusion, such as a drop in systolic and/or diastolic blood pressure of ≥ 20 mmHg fever/chills, nausea/vomiting, back pain, dark or red urine, no or poor increase of Hb level or an unexpected drop in Hb.

Delayed hemolytic transfusion reaction

Signs or symptoms of hemolysis occurring from 24 hours to a maximum of 28 days after transfusion, such as: unexplained drop in hemoglobin, dark urine, fever or chills, or laboratory findings indicating hemolysis.

TRALI (Transfusion-related acute lung injury)

Features of acute lung injury such as dyspnoea and hypoxia during or within 6 hours after a transfusion; chest X-ray shows bilateral pulmonary infiltrates.

Transfusion-associated circulatory overload (TACO)

Respiratory problems during or within 12 hours after transfusion, manifested by at least one pulmonary feature (criterion A or B). In all, at least 3 of the criteria below must be met.

A. New or worsening respiratory problems (see note 1)
B. Features of new or worsening pulmonary oedema, based on:

•    Physical examination (see note 2) and/or
•    Chest X-ray or other imaging of the chest (see note 3)

C. Relevant changes in the cardiovascular system (see note 4)
D. Findings suggestive of relevant changes in fluid balance (see note 5)
E. Biomarker result(s) consistent with TACO (see note 6)

Click here for the full (TRIP) TACO definition with notes.

Transfusion-associated dyspnea

Shortness of breath or hypoxia during or up to 24 hours after transfusion, but the criteria for  TRALI, TACO and allergic (anaphylactic) reaction are not met. Respiratory problems are the most prominent feature and they cannot be explained by the patient’s underlying medical condition or another known medical cause.

Anaphylactic transfusion reaction

Rapidly developing allergic reaction occurring within a few seconds after the start of transfusion or up till a short time after transfusion with features such as stridor, fall in systolic and/or diastolic blood pressure ≥ 20mm Hg, nausea/vomiting, diarrhoea, back pain, skin rash.

Other allergic reaction

Allergic phenomena such as itching, redness or urticaria without objective respiratory, cardiovascular or gastrointestinal features, arising from a few minutes of starting transfusion until a few hours after its completion.

New allo-antibody

After receiving a transfusion, demonstration of clinically relevant antibodies against blood cells (irregular antibodies, HLA or HPA antibodies) that were not present previously (as far as is known in that hospital).

Post-transfusion bacteremia/sepsis

Clinical symptoms of bacteremia/sepsis arising during, directly after or some time subsequent to a blood transfusion, with a relevant positive patient blood culture result; a causal link to a transfused blood component may or may not be confirmed (through a finding of the same bacterial species in the component or other material from the donor).

Post-transfusion viral infection

Demonstration of a viral infection in a transfused patient within a period corresponding to the incubation period of that infection, leading to investigation of a possible a causal link to a transfused unit

Post-transfusion other infection

Demonstration of an potentially blood-transmitted infection with an agent other than a virus or bacterial species in a patient during or some time after administration of a blood transfusion; a causal link may or may not be confirmed.

Post-transfusion purpura (PTP)

Transient serious thrombocytopenia possibly with bleeding manifestations 1-24 days after transfusion of a red cell or platelet concentrate.


Iron overload induced by frequent transfusion with a minimum ferritin level of 1000 micrograms/l, with or without organ damage.

Transfusion-associated graft versus host disease (TA-GvHD)

Clinical features of graft versus host disease such as erythema which starts centrally, watery diarrhoea, fever and rise in liver enzymes 1-6 weeks (usually 8-10 days) after transfusion of a T-cell containing (nonirradiated) blood component.

Other transfusion reaction

Transfusion reaction which does not fit into the categories above.

Incorrect blood component transfused (IBCT)

All cases in which a patient was transfused with a component that did not fulfil all the requirements of a suitable component for that patient, or that was intended for a different patient.

Incorrect blood component transfused in the past (additional category)

On investigation of a transfusion reaction or incident it is discovered that the patient previously received an incorrect blood component.

Near miss

Any error that, if undetected, could have led to a wrong blood group result or issue or administration of an incorrect blood component, and which was detected before transfusion.

Other incident

Error or incident in the transfusion chain that does not fit into any of the above categories, for instance patient transfused whereas the intention was to keep the blood component in reserve, or transfusing unnecessarily on the basis of an incorrect Hb result or avoidable wastage of a blood component.

Calculated risk situation

A situation where the clinician knowingly decides to proceed with transfusion in the presence of an increased risk or anticipated potential side effect of the transfusion as mentioned in the transfusion guidelines and where the intended benefit from transfusion is deemed to justify the risk of harm and its possible severity.

Bacterial contamination of a blood component*

Relevant numbers of bacteria in a (remnant of) blood component or in the bacterial screen bottle of a platelet component, or in material from the same donation, demonstrated in the approved way with laboratory techniques, preferably including typing of the bacterial strain or strains.

Note: This commonly occurs in the setting of the routine bacterial screening of platelet concentrates, which are distributed “negative to date”. If there is subsequently a positive screening result the hospital is notified by the blood supplier Sanquin.

Look-back by the supplier*

Retrospective notification of a possibly infectious donation, leading to investigation of the recipient for that infection.

* If there was a notification from the Sanquin but the patient had no reaction or other medical consequences, hospitals should not report these cases to TRIP. Sanquin supplies the overall total figures to TRIP annually.