Transfusion Medicine & Transfusion Reactions

Meet the patient

Mrs K is 82, carries heart failure, and is two hours into her first unit of packed cells for an Hb of 64 when the nurse calls you across: breathless, sat up, saturating 88 percent, JVP to the jaw, fine crackles to the apices, and the fluid chart reads 700 mL in.[2]

Three bays away a young trauma call is three minutes into emergency O positive blood when he rigs, clutches his flank, drops his pressure, and the catheter bag turns the colour of port wine. Two units, two reactions, two opposite problems — one patient is drowning in the drip, the other is being haemolysed by it.[1]

Both need the same first move and a different second move. Hold that frame and every section below falls into place: a transfusion is a liquid transplant whose commonest fatal error is mislabelling, whose threshold is restrictive, and whose reactions turn on one bedside question — is this lung wet from volume, or from injury?[1][2]

A transfusion is a liquid transplant

Every unit is a liquid transplant — donor cells, donor plasma proteins, and residual donor leucocytes placed into a living recipient. The benefit is real (oxygen carriage in anaemia, platelets in thrombocytopenia, clotting factors in coagulopathy, volume in haemorrhage); so is the risk — immune, infectious, and circulatory.[1][2]

Three skills keep a transfusion safe, and examiners test all three. Match the component to the deficit — anaemia gets red cells, not "blood"; coagulopathy gets FFP or cryoprecipitate; thrombocytopenia gets platelets. Check at the bedside — the commonest fatal error is ABO mismatch from clerical mislabelling, prevented only by mandatory two-person identification. Recognise reactions in the first five minutes, because that window decides who survives.[1]

One cardinal rule governs every reaction, every time: STOP the transfusion, maintain IV access, assess the patient, keep the unit and giving set, take fresh patient samples, return them to the blood bank, and report — then chase the specific mechanism. The restrictive threshold (Hb under 70 g/L in stable adults) is the standard of care, locked in place by TRICC, FOCUS, TRISS, and the AABB 2023 guidelines.[9][1][3][4][6]

The universal-donor map — O negative gives cells, AB gives plasma

ABO is the single most important determinant of transfusion safety, because anti-A and anti-B are naturally occurring IgM — you are born ready to attack. Forged in the first year of life against gut-flora polysaccharides, they fix complement with brutal efficiency, which is why an ABO-incompatible unit is the commonest cause of a fatal acute haemolytic reaction. The "universal donor" is universal only because O's red cells wear nothing for the recipient to attack — the courtesy does not extend to O plasma.[1]

The ABO antigens are carbohydrate groups on the red-cell surface, built by glycosyltransferases encoded on chromosome 9. The four groups, and the antibody each carries in its plasma:[1]

• Group A — A antigen on the red cell; anti-B (IgM) in plasma.
• Group B — B antigen on the red cell; anti-A (IgM) in plasma.
• Group AB — both A and B antigens; neither anti-A nor anti-B in plasma — the universal plasma donor (no antibodies to attack a recipient).
• Group O — neither A nor B antigen; both anti-A and anti-B (IgM) in plasma — the universal red-cell donor (no A/B antigens to be attacked), but a dangerous plasma donor. [1]

The Rhesus system is the second axis, and only RhD matters at the bedside. RhD-negative people do NOT make anti-D naturally — they form it only after sensitisation, by an RhD-positive fetus or an RhD-positive unit. Once formed it is IgG: it crosses the placenta (haemolytic disease of the fetus and newborn) and drives extravascular haemolysis on the next exposure.[1]

The compatibility table examiners expect, reproduced exactly:[1]

Rh in practice — give RhD-negative cells to RhD-negative recipients to avoid sensitisation; RhD-positive recipients take either. In the emergency unit, O negative goes to females of childbearing potential and O positive to males and post-menopausal women, so the precious O-negative stock is not bled dry for the people who do not need it.[1]

[1]

Match the component to the deficit — never reach for "blood"

The first question on every prescription is not "does this patient need blood?" but "which component, for which deficit?" Anaemia is a red-cell problem; coagulopathy is a plasma problem; thrombocytopenia is a platelet problem — reaching for a bag of "blood" treats none of them correctly.[1]

• Red cells (PRBCs) — for anaemia and haemorrhage; the 2023 AABB international guidelines recommend a restrictive strategy, considering transfusion when Hb is under 7 g/dL in haemodynamically stable hospitalised adults.[1]
• Platelets — prophylaxis in hospitalised adults with therapy-induced hypoproliferative thrombocytopenia: transfuse at a platelet count of 10 x 10^9/L or less; transfuse under 20 x 10^9/L before elective central venous catheter placement; under 50 x 10^9/L before elective diagnostic lumbar puncture or major elective non-neuraxial surgery. Dose: up to a single apheresis unit or equivalent — greater doses are not more effective, and half-standard doses are equally effective.[8]
• Fresh frozen plasma and prothrombin complex concentrate — for bleeding with coagulopathy; for urgent vitamin-K-antagonist reversal, four-factor PCC achieves rapid INR reduction and higher vitamin-K-dependent factor levels than plasma and allows earlier surgery.[12]
• Cryoprecipitate and plasma in DIC — transfusion of platelets or plasma should be reserved for patients who present with bleeding, not triggered by laboratory results alone; the cornerstone is treatment of the underlying condition.[13]

Special products modify a component for a specific patient — leucodepleted, CMV-negative, irradiated, washed, or volume-reduced:[1][2]

• Leucodepleted (standard in most high-income countries) — fewer febrile non-haemolytic reactions, less CMV transmission, less alloimmunisation.
• CMV-negative — for pregnant women, neonates, intrauterine transfusion, stem-cell transplant recipients, and severely immunocompromised patients.
• Irradiated (25 Gy) — for stem-cell transplant recipients, haematological malignancy on fludarabine/cladribine/alemtuzumab, congenital immunodeficiency, intrauterine or neonatal exchange transfusion, and first-degree relatives as donors; prevents transfusion-associated graft-versus-host disease (TA-GVHD) by inactivating donor T-lymphocytes.
• Washed — for recurrent severe allergic reactions and confirmed IgA deficiency with anti-IgA; removes donor plasma.
• Methlene-blue or pathogen-reduced plasma — additional viral/bacterial kill.
• Volume-reduced — for severe volume intolerance, TACO-prone patients. [1]

[1] [8] [12]

The three minutes that stop the killer — group, screen, two-person check

The aim of testing is to deliver a unit the recipient has no antibody against — and the test that prevents the most deaths is the two-person bedside check, not the laboratory assay.[1]

• Group and screen — ABO and RhD group of the recipient, plus an antibody screen (indirect antiglobulin test, IAT) against a panel of group O reagent red cells expressing the common clinically significant antigens (Rh, Kell, Duffy, Kidd). The antibody screen detects irregular antibodies formed by prior transfusion or pregnancy.
• Crossmatch — recipient serum is incubated with donor red cells to confirm compatibility. Electronic (computer) crossmatch is now standard when group-and-screen shows no antibodies; an immediate-spin crossmatch detects ABO incompatibility; a full IAT crossmatch is used when an antibody is present.
• Sample validity — group-and-screen samples are valid for 3 days (72 hours) in patients transfused or pregnant in the previous 3 months, and 7 to 14 days otherwise. Always label the sample at the bedside, in the presence of the patient, against two identifiers (full name and date of birth), and never pre-label.
• Bedside check — at administration, two clinicians independently confirm patient identity (name, date of birth, wristband), unit compatibility (recipient details on the bag match the patient), expiry date, and unit integrity (no clots, no discolouration). This single step prevents most fatal ABO-mismatch errors.[1]

One unit then reassess — the restrictive ladder

The international standard is now firmly restrictive — for most haemodynamically stable hospitalised adults, transfusion is considered only when the Hb falls under 70 g/L.[1]

Red blood cells (PRBCs)[1][3][4][6]

• Hb under 70 g/L — most stable hospitalised adults, including ICU; AABB 2023 Recommendation 1 for hemodynamically stable hospitalized adults.[1]
• Hb under 70 g/L in septic shock — TRISS (998 patients): transfusing at 7 g/dL versus 9 g/dL gave similar 90-day mortality, ischaemic events and life-support use; the lower threshold meant fewer units.[6]
• Hip-fracture surgery in patients 50 or over — FOCUS (2016 patients): a liberal threshold of 10 g/dL did not reduce death or inability to walk at 60 days versus a restrictive strategy (symptoms, or physician discretion under 8 g/dL).[4]
• Critical care — TRICC (838 patients): transfusing below 7.0 g/dL (maintaining 7.0 to 9.0) was at least as effective as transfusing below 10.0 g/dL, with lower 30-day mortality among patients with APACHE II scores of 20 or less and those under 55.[3]

Platelets — prophylactic for thrombocytopenia from bone-marrow failure:[1]

• under 10 x 10^9/L — prophylaxis in stable, afebrile chemotherapy/leukaemia patients.
• under 20 x 10^9/L — febrile or with risk factors (sepsis, mucositis, recent bleeding, high blast count).
• under 50 x 10^9/L — before invasive procedures (central line, lumbar puncture, transbronchial biopsy, epidural, surgery).
• Active bleeding or before surgery — keep above 50 (general surgery) or above 100 (neurosurgery, ophthalmic, retinal).
• Platelet dysfunction (antiplatelet drugs, uraemia, cardiopulmonary bypass) — transfuse despite a normal count if bleeding.
• Do NOT transfuse prophylactically in immune thrombocytopenia, heparin-induced thrombocytopenia, or thrombotic thrombocytopenic purpura — they are rapidly consumed and HIT/TTP are pro-thrombotic. [1]

Fresh frozen plasma[1]

• INR over 1.5 with active bleeding, or before emergency surgery/invasive procedure with multiple factor deficiency.
• Warfarin reversal if PCC unavailable (slower, larger volume).
• Massive haemorrhage as part of ratio-based resuscitation.
• Single-factor deficiency — use specific factor concentrate if available. [1]

Cryoprecipitate and fibrinogen replacement [13]

• In DIC, platelet or plasma transfusion should in general be reserved for patients who present with bleeding, not triggered by laboratory results alone; repeat testing to monitor the dynamically changing picture, and treat the underlying condition as the cornerstone.[13]

Prothrombin complex concentrate (PCC)

• Urgent reversal of vitamin-K-antagonist therapy before urgent surgery or invasive intervention in patients with INR 2 or above.[12]
• In a randomised trial population needing urgent orthopaedic surgery, four-factor PCC achieved rapid INR reduction in 43.3 percent of patients versus 0 percent with plasma, restored vitamin-K-dependent factor levels within 3 hours, and shortened the median time to surgery from 19.2 to 5.8 hours.[12]

Acute or delayed, immune or not — the reaction map

Sort every reaction by timing (acute under 24 h vs delayed) and mechanism (immune vs non-immune) — the two axes map straight onto the differential and the treatment.[1][2]

How common, how lethal — the numbers behind the preventable deaths

• Acute non-haemolytic febrile and allergic reactions are the commonest complication of transfusion and often result in little or no morbidity — but prompt recognition and management are essential.[9]
• TACO and TRALI are the leading causes of transfusion-related fatality; both are syndromes of acute respiratory distress occurring within 6 hours of transfusion — TACO characterised by pulmonary hydrostatic (cardiogenic) oedema, TRALI by pulmonary permeability (noncardiogenic) oedema.[2]
• The UK haemovigilance scheme SHOT (Serious Hazards of Transfusion) receives 30 to 40 reports of anaphylactic reactions each year — and other serious complications (acute haemolysis, bacterial contamination, TRALI, TACO) can present with similar clinical features to routine febrile or allergic reactions, which is why every reaction is investigated before it is dismissed as minor.[9]

Mechanism dictates treatment — from IgM to endotoxin

Learn the mechanism and the treatment writes itself — each reaction below is paired with the move it forces.[1][2]

• Acute haemolytic — one of the serious complications that can masquerade as a routine febrile reaction; prompt recognition, stopping the transfusion, and laboratory investigation to establish the likely cause are essential.[9]
• Febrile non-haemolytic and allergic reactions — the common acute reactions: usually little or no morbidity, but they must be distinguished from the serious mimics before the transfusion is restarted.[9]
• TRALI — pulmonary permeability (noncardiogenic) oedema within 6 hours of transfusion; a two-hit model — the recipient's underlying condition plus a transfusion trigger — is generally assumed to underlie its pathophysiology.[2]
• TACO — pulmonary hydrostatic (cardiogenic) oedema within 6 hours of transfusion, in recipients with limited physiological reserve; distinguishing TACO from TRALI and from underlying causes of fluid overload remains very challenging.[2]
• Bacterial contamination — named alongside acute haemolysis, TRALI and TACO as a serious complication that can present with the same clinical features as a routine febrile reaction.[9]
• Iron overload — the most important cause of mortality in transfusion-dependent thalassaemia major; assess with MRI of liver and cardiac iron and treat with chelation — oral deferiprone, oral deferasirox, or parenteral desferrioxamine.[11]

At the bedside — what the first five minutes show you

Tempo and constellation tell the reactions apart at the bedside — read the clock and the vital signs together.[1][2]

Acute haemolytic (under 24 h, often within minutes) — fever, chills, flank, chest or back pain, hypotension, tachypnoea, haemoglobinuria (dark red/coca-cola urine), nausea, flushing, bleeding from DIC, and a sense of impending doom. Under anaesthesia: diffuse bleeding, hypotension, dark urine in the catheter bag, unexplained rise in airway pressure. A medical emergency — speed of recognition determines outcome. [1]

TRALI (within 6 h) — acute dyspnoea and hypoxia, fever, hypotension, tachycardia with bilateral infiltrates on chest X-ray, normal or low cardiac filling pressures (non-cardiogenic), no fluid overload, no raised BNP. Often transient and resolves within 48 to 96 hours with supportive care; severe cases need ventilatory support.[2]

TACO (within 6 to 12 h) — dyspnoea, orthopnoea, hypertension, raised JVP, bilateral crackles, positive fluid balance, often in elderly or cardiac/renal patients; raised brain natriuretic peptide; responds to diuresis.[2]

Allergic (urticarial) — localised or generalised pruritic urticaria, flushing; no fever, no hypotension. Anaphylactic — bronchospasm (wheeze, stridor), angio-oedema, hypotension, abdominal cramping, often within minutes of starting the unit, in an IgA-deficient recipient. [1]

Febrile non-haemolytic — temperature rise of at least 1 degree C with rigors, often after the first unit; no haemolysis, no haemoglobinuria; the commonest reaction. [1]

Bacterial sepsis — very high fever (over 39 degrees C), severe rigors, hypotension, nausea and vomiting, often during or very soon after a platelet transfusion; rapid progression to septic shock. [1]

Delayed haemolytic (3 to 14 days) — unexplained fall in Hb with mild jaundice, occasionally mild fever; positive direct antiglobulin test; spherocytes on film. [1]

Post-transfusion purpura (5 to 10 days) — sudden severe thrombocytopenia with mucocutaneous bleeding. [1]

TA-GVHD (4 to 30 days) — fever, maculopapular rash, diarrhoea, hepatitis, pancytopenia; usually fatal. [1]

Iron overload (years) — fatigue, diabetes, cardiomyopathy, cirrhosis, hypogonadism, hyperpigmentation — in chronically transfused patients (thalassaemia major, MDS, sickle cell). [1]

TRALI or TACO? — the one bedside question that decides the drip

Two reactions, one presentation — acute dyspnoea with bilateral infiltrates within 6 hours of transfusion — and the treatment is exactly opposite: diurese TACO, support TRALI. Get it backwards and you kill the patient with the right drug for the wrong disease.[2]

One-line discriminator: positive fluid balance with a raised BNP is TACO; a dry, hypotensive patient with a normal BNP is TRALI.[2]

And which fever is it? Every temperature during a transfusion runs through the universal reaction rule, then splits three ways:[1][2]

• Febrile non-haemolytic — mild, no haemolysis, the commonest; settle with paracetamol and a slower rate.
• Acute haemolytic — haemoglobinuria, DIC, hypotension, flank pain; the emergency.
• Bacterial sepsis — very high fever, rigors, hypotension, after platelets; cultures and broad-spectrum antibiotics.[1]

Separate them with LDH, haptoglobin, DAT, urine for haemoglobin, and blood cultures of patient and unit. Always reconsider whether the fever is the patient's own illness rather than the unit — infection, malignancy, drug reaction — and reassess after stopping.[1][2]

Anaphylaxis during a transfusion shifts the differential to IgA deficiency with anti-IgA (check serum IgA), latex allergy, a concurrent drug, or a complement reaction to a plasma-rich product.[1]

STOP the unit, keep the line — the universal reaction rule

For any reaction the sequence is fixed, and step one never changes.[1]

1. STOP the transfusion immediately; do not restart the unit.
2. Maintain IV access with normal saline; keep the cannula open.
3. ABCDE assessment — airway (stridor? angio-oedema?), breathing (oxygen saturation, wheeze or crackles, respiratory rate), circulation (BP, pulse, perfusion, capillary refill), disability (conscious level), exposure (skin — urticaria, flushing, rash).
4. Look for the red flags of acute haemolysis — flank or back pain, bleeding, red urine (haemoglobinuria), hypotension.
5. Look for the red flags of TRALI/TACO — bilateral crackles, raised JVP, hypertension (TACO) vs hypotension (TRALI), positive fluid balance, oxygen requirement.
6. Review the prescription against the indication and threshold — was the restrictive strategy applied? Was the unit needed?
7. Fluid status is decisive for separating TRALI from TACO — examine the JVP, auscultate the lungs, weigh the patient, and review input/output charts and fluid balance.
8. Document vital signs before, during, and after the reaction. [1]

The post-reaction panel — what to send to the lab and the bank

Post-reaction bloods[1][2]

• Full blood count, blood film — baseline Hb, platelets, spherocytes (extravascular haemolysis).
• LDH, haptoglobin, bilirubin, DAT (direct antiglobulin test) — for haemolysis (LDH raised, haptoglobin low, DAT positive in immune haemolysis).
• Coagulation — PT, APTT, fibrinogen, D-dimer (DIC in acute haemolysis).
• U&E, creatinine — acute kidney injury in acute haemolysis.
• Blood cultures of patient AND of the unit — bacterial contamination.
• Plasma free haemoglobin — intravascular haemolysis in acute haemolytic. [1]

Repeat group, antibody screen and crossmatch; urine for haemoglobinuria (acute haemolytic). Return the donor unit and giving set to the blood bank for Gram stain and culture of the unit and repeat compatibility testing. [1]

TRALI vs TACO workup — chest X-ray (bilateral infiltrates in both, normal heart size), brain natriuretic peptide (raised in TACO, normal in TRALI), echocardiogram if available; send donor and recipient samples for HLA/neutrophil antibody investigation (TRALI). For suspected IgA deficiency: serum IgA level and anti-IgA antibodies after recovery.[2]

The three reactions that kill within an hour — name them

1. Acute haemolytic (ABO mismatch) — IgM + complement, intravascular haemolysis, DIC.
2. Anaphylaxis (IgA-deficient recipient) — bronchospasm, hypotension within minutes.
3. Bacterial contamination (platelets) — high fever, rigors, septic shock. Plus TRALI (lung injury, under 6 h, support not diurese) and TACO (overload, diurese) — both can also be fatal in elderly or comorbid patients.

[1]

Reaction-specific treatment — diurese TACO, support TRALI

For any reaction, the first action is always the same:[9]

Then manage the specific reaction: [9]

• Every acute reaction — stop the transfusion, assess and treat the patient, investigate to establish a likely cause, and report: that is the sequence the BCSH guideline sets out for any adverse symptoms or signs during transfusion.[9]
• TRALI and TACO — both cause acute respiratory distress within 6 hours; TACO is cardiogenic (hydrostatic) oedema and TRALI non-cardiogenic (permeability) oedema. Specific therapies are unavailable, so management is supportive and directed at which mechanism is operating.[2]
• Anaphylaxis — a recognised serious transfusion reaction (SHOT receives 30 to 40 reports each year): stop the transfusion, treat the anaphylaxis, investigate and report.[9]
• Bacterial contamination — may present like a routine febrile reaction: stop, investigate to establish the likely cause, treat, and report.[9]
• Iron overload — the most important cause of mortality in transfusion-dependent thalassaemia major and other transfusion-dependent haemoglobinopathies; chelation options are oral deferiprone, oral deferasirox and parenteral desferrioxamine, guided by MRI assessment of liver and cardiac iron.[11]

1:1:1 and tranexamic acid within three hours — the massive haemorrhage protocol

Severe trauma with major bleeding is where product-ratio evidence lives: earlier transfusion with higher blood product ratios — plasma, platelets and red cells together — defines damage control resuscitation.[7]

What the trials put in the protocol box:[5][7]

• PROPPR trial (Holcomb 2015, JAMA) — in severe trauma with major bleeding, a 1:1:1 ratio (RBC:plasma:platelets) achieved faster haemostasis and fewer deaths from exsanguination within 24 hours compared with 1:1:2, although 24-hour and 30-day mortality did not differ significantly.[7]
• Tranexamic acid — CRASH-2 (20 211 trauma patients): a 1 g loading dose over 10 minutes then 1 g over 8 hours, started within 8 hours of injury, reduced all-cause mortality (14.5 vs 16.0 percent; RR 0.91) and death due to bleeding (4.9 vs 5.7 percent; RR 0.85). Timing matters: treatment within 1 hour of injury cut bleeding deaths (RR 0.68), and 1 to 3 hours still helped (RR 0.79), but beyond 3 hours treatment seemed to increase the risk of death due to bleeding — give it as early as possible.[5][10]

[5] [10] [1]

Pregnant, neonate, immunocompromised, elderly — and the Jehovah's Witness

• Patients with limited cardiac or fluid-balance reserve — TACO is cardiogenic oedema within 6 hours of transfusion; a restrictive strategy and careful fluid-balance assessment limit the risk.[2]
• Major bleeding — ratio-based resuscitation (1:1:1 achieved faster haemostasis and fewer exsanguination deaths in PROPPR) plus tranexamic acid as early as possible after injury (CRASH-2).[7][5]
• Patients who decline transfusion (e.g., Jehovah's Witnesses) — the AABB 2023 panel advises that it is good practice to consider the overall clinical context and alternative therapies to transfusion when making transfusion decisions; document the patient's specific wishes.[1]
• Chronic transfusion (thalassaemia major, sickle cell disease, other congenital anaemias) — iron overload is the most important cause of mortality in thalassaemia major: assess body iron with MRI of liver and heart, and chelate with oral deferiprone, oral deferasirox or parenteral desferrioxamine.[11]

The three pillars — treat the anaemia before you transfuse

PBM is the multidisciplinary, evidence-based bundle that minimises the need for transfusion by treating the three pillars:[1]

1. Treat the anaemia itself — the AABB 2023 panel states it is good practice to consider alternative therapies to transfusion for the individual patient.[1]
2. Minimise blood loss — tranexamic acid reduces bleeding in elective surgery and reduced mortality in bleeding trauma patients (CRASH-2).[5]
3. Transfuse restrictively — the single most visible element: consider RBC transfusion only under Hb 70 g/L in haemodynamically stable hospitalised adults.[1]

The restrictive transfusion strategy is the bundle's single most visible element.[1]

The preventable deaths and the chronic burdens

• Death from ABO-incompatible transfusion — preventable, almost always a clerical/identification error; two-person bedside checking is the single most important preventive step.[1]
• Acute kidney injury and DIC from massive intravascular haemolysis in acute haemolytic reaction.
• ARDS and respiratory failure from TRALI; pulmonary oedema from TACO.[2]
• Iron overload (transfusional haemosiderosis) in chronically transfused patients — cardiomyopathy (leading cause of death in transfusion-dependent thalassaemia), cirrhosis, hepatocellular carcinoma, diabetes, hypogonadism, hyperpigmentation, arthritis.
• Alloimmunisation and delayed haemolytic reactions complicating future transfusions — prevent with extended-phenotype matching in chronic transfusion.
• Transfusion-associated graft-versus-host disease in immunocompromised patients (prevent with irradiated products; usually fatal).
• Transfusion-transmitted infection — now extremely rare with nucleic-acid testing (HIV risk ~1 in 2 million units, Hepatitis C ~1 in 2 million, Hepatitis B ~1 in 200 000 to 1 in 1 million), but emerging threats (Creutzfeldt-Jakob disease variant, Zika, dengue, malaria, Babesia) remain.
• Hypocalcaemia, hypothermia, hyperkalaemia, acidosis from massive transfusion of stored blood (citrate chelates calcium; stored red cells leak potassium).
• Transfusion-associated circulatory overload in elderly/cardiac/renal patients — prevent with slow, single-unit transfusion and diuretic prophylaxis.

Who survives, who is reported — disposition and haemovigilance

• Acute haemolytic reaction — outcome depends on the volume of incompatible blood and the speed of recognition; early STOP and aggressive fluids improve survival; mortality can be 5 to 10 percent in severe cases.[1]
• TRALI — mortality 5 to 10 percent; usually resolves within 48 to 96 hours with supportive care; diuresis is unhelpful (patients are not volume overloaded).[2]
• TACO — mortality 5 to 15 percent; worse in elderly and cardiac/renal patients; preventable with slow transfusion and diuretics.[2]
• TA-GVHD — mortality over 90 percent; preventable only by irradiation.
• Restrictive strategy — at least as safe as liberal, with fewer reactions, infections, and lower cost — confirmed in TRICC (ICU), FOcus (hip fracture), TRISS (septic shock), and AABB 2023 guidelines.[1][3][4][6]
• Chronic transfusion survival — governed by iron-overload control (chelation adherence); cardiomyopathy is the leading cause of death in transfusion-dependent thalassaemia.
• Disposition — any patient with a significant reaction is admitted or observed; the universal rule applies: STOP, investigate, report. All reactions are reported to the hospital transfusion committee and the national haemovigilance system (SHOT in UK, FDA in US).

The trials that locked the thresholds

[3] [4] [6] [5] [10] [1] [9] [1] [1] [1]

The consultant's cheat-sheet — thirteen lines that decide a viva

• Universal reaction rule — STOP, assess, treat, investigate to establish a likely cause, and report. Tested in every format.[9]
• Acute haemolytic reaction — one of the serious complications (with bacterial contamination, TRALI and TACO) that can present with the same clinical features as a routine febrile reaction; stop, investigate and report.[9]
• Restrictive RBC threshold — Hb under 70 g/L in haemodynamically stable hospitalised adults; higher thresholds for cardiac surgery and for orthopaedic surgery or preexisting cardiovascular disease.[1]
• TRALI vs TACO — both acute respiratory distress within 6 hours; TACO is cardiogenic (hydrostatic) oedema, TRALI non-cardiogenic (permeability) oedema.[2]
• Anaphylaxis on transfusion — a recognised serious reaction (30 to 40 SHOT reports a year): stop, treat the anaphylaxis, investigate and report.[9]
• Severe rigors and sepsis after platelets — bacterial contamination is one of the serious mimics of a routine febrile reaction; stop, investigate and report.[9]
• Components — platelets at 10 x 10^9/L or less for prophylaxis in hypoproliferative thrombocytopenia (under 20 before central lines, under 50 before lumbar puncture or major surgery); four-factor PCC for urgent vitamin-K-antagonist reversal (rapid INR reduction where plasma achieves none).[8][12]
• Massive transfusion — 1:1:1 achieved faster haemostasis and fewer exsanguination deaths at 24 hours than 1:1:2 (PROPPR); tranexamic acid as early as possible — benefit greatest within 1 h, still present at 1 to 3 h, possible harm after 3 h (CRASH-2).[7][5][10]
• Chronic transfusion — iron overload is the most important cause of mortality in thalassaemia major; chelate with oral deferasirox, oral deferiprone or parenteral desferrioxamine, guided by MRI of liver and cardiac iron.[11]
• Universal donors — RBC = O negative; plasma = AB; recipient RBC = AB positive.
• Naturally occurring antibodies — anti-A and anti-B are IgM (born ready); anti-D is IgG, formed only after sensitisation.
• Jehovah's Witnesses — document specific wishes; never transfuse against informed refusal in a competent adult.

Ward-round test

Stem 1. Mrs K, 82, heart failure, two hours into a unit of red cells: breathless, sat up, saturating 88 percent, JVP to the jaw, crackles to the apices, and a 700 mL positive fluid chart. Which of the two leading causes of transfusion-related fatality is this, and what feature separates it from the other one?[2]

Stem 2. A 24-year-old man, three minutes into his first ever transfusion, becomes wheezy and hypotensive with angio-oedema. What is the reaction, what must you do in the next minute, and to whom must it be reported?[9]

Stem 3. A neutropenic leukaemia patient rigs and spikes midway through a platelet transfusion. Which serious complication must be excluded before this is called a routine febrile reaction, and what is the sequence of management?[9]

Stem 4. A multiply-transfused thalassaemia major patient is found to have a falling ejection fraction at 28. What is the most important cause of mortality in this group, and which chelation options are on the table?[11]

Answers

1 — TACO. Acute respiratory distress within 6 hours of transfusion, raised JVP and positive fluid balance fit cardiogenic (hydrostatic) oedema; TRALI would be permeability (non-cardiogenic) oedema without fluid overload. TACO and TRALI are the leading causes of transfusion-related fatality, distinguishing them is diagnostically challenging, and specific therapies are unavailable — management is supportive and directed at the mechanism.[2] 2 — Anaphylaxis. Stop the transfusion, assess and treat the reaction, investigate to establish the likely cause, and report it — SHOT receives 30 to 40 anaphylaxis reports each year.[9] 3 — Bacterial contamination must be excluded. It is one of the serious complications (with acute haemolysis, TRALI and TACO) that can present with the same clinical features as a routine febrile reaction: stop, investigate, treat and report.[9] 4 — Iron overload. Iron overload is the most important cause of mortality in transfusion-dependent thalassaemia major; chelation options are oral deferiprone, oral deferasirox and parenteral desferrioxamine, with MRI to assess liver and cardiac iron.[11]

The mantra

STOP the unit, keep the line, find the cause — then diurese TACO, support TRALI.[1][2]

References

1. [1]Carson JL, Stanworth SJ, Guyatt G, et al. Red Blood Cell Transfusion: 2023 AABB International Guidelines JAMA, 2023.PMID 37824153
2. [2]Semple JW, Rebetz J, Kapur R. Transfusion-associated circulatory overload and transfusion-related acute lung injury Blood, 2019.PMID 30808638
3. [3]Hébert PC, Wells G, Blajchman MA, et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group N Engl J Med, 1999.PMID 9971864
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