Transfusion Reactions

Topic Overview

Summary

Transfusion reactions are adverse clinical events occurring during or after blood product transfusion, ranging from mild self-limiting reactions to life-threatening emergencies. These reactions are classified as acute (occurring within 24 hours) or delayed (beyond 24 hours), with mechanisms including immune-mediated, non-immune, and infectious etiologies. The most common reaction is febrile non-haemolytic transfusion reaction (FNHTR), affecting 0.1-1% of transfusions, while the most dangerous is acute haemolytic transfusion reaction (AHTR) due to ABO incompatibility, which has mortality rates of 10-40%. [1,2]

Recognition requires high clinical suspicion—any new symptom during transfusion warrants immediate cessation and systematic investigation. The two most challenging differential diagnoses are TRALI (transfusion-related acute lung injury) versus TACO (transfusion-associated circulatory overload), which require distinct management approaches. [2,3]

Key Facts

• Incidence: Overall adverse reactions occur in approximately 1-3% of all transfusions [4]
• Most common: Febrile non-haemolytic transfusion reaction (FNHTR) - 0.1-1% of transfusions [5]
• Most dangerous: Acute haemolytic reaction from ABO incompatibility - 1 in 38,000 to 1 in 70,000 transfusions [4]
• Leading cause of transfusion-related mortality: TRALI and TACO collectively account for > 60% of transfusion-related deaths [2,6]
• Preventable errors: 70% of fatal haemolytic reactions result from clerical errors in patient identification [3]
• TRALI vs TACO: TRALI occurs in 1:5,000-12,000 transfusions; TACO in 1-11% depending on patient population [2,7]

Clinical Pearls

Universal Rule: ANY new symptom during transfusion = STOP transfusion immediately and assess. Never assume a reaction is "just fever" without excluding haemolysis or bacterial contamination. [3]

The Identity Check Saves Lives: Most fatal ABO incompatibility reactions result from wrong blood to wrong patient—always verify patient identity against blood unit labels at the bedside. [3,8]

TRALI vs TACO Discriminators: TRALI presents with hypotension/normotension and normal JVP; TACO presents with hypertension and elevated JVP. BNP/NT-proBNP levels help distinguish: elevated in TACO, normal/low in TRALI. [2,7,9]

Haemoglobinuria is Haemolysis Until Proven Otherwise: Dark red or brown urine during transfusion indicates intravascular haemolysis—requires urgent intervention to prevent acute kidney injury. [3,10]

Don't Give Diuretics for TRALI: TRALI is non-cardiogenic pulmonary oedema; diuretics are ineffective and potentially harmful. Supportive care with oxygen ± mechanical ventilation is the mainstay. [2,11]

Why This Matters Clinically

Transfusion reactions represent a critical intersection of haematology, emergency medicine, and patient safety. Despite blood being among the most regulated medical products, transfusion-related complications remain a leading cause of iatrogenic morbidity and mortality in hospital settings. [1,4]

The UK Serious Hazards of Transfusion (SHOT) reports consistently demonstrate that most serious reactions are preventable through rigorous adherence to identification protocols and appropriate patient selection. [8] Early recognition and appropriate management of acute reactions can prevent progression to DIC, acute kidney injury, or respiratory failure. [3,10]

The burden extends beyond immediate patient harm—transfusion reactions consume significant healthcare resources through extended ICU stays, additional investigations, and delayed surgical procedures. Understanding the pathophysiology, presentation patterns, and evidence-based management of transfusion reactions is essential for all clinicians involved in transfusion medicine. [1,4]

---

Visual Summary

Visual assets to be added:

• Comprehensive transfusion reaction classification flowchart
• TRALI vs TACO comparison table with clinical, laboratory, and radiological features
• Acute transfusion reaction management algorithm (stop-assess-investigate-treat)
• Bedside checking procedure infographic
• Timeline of acute vs delayed reactions
• Pathophysiology diagrams for AHTR, TRALI, and TACO mechanisms

---

Epidemiology

Incidence and Prevalence

Transfusion reaction rates vary significantly based on reaction type, blood product, and patient population characteristics. [4,5]

Temporal Trends

Introduction of universal leukoreduction has reduced FNHTR rates by approximately 50-75% in countries implementing this measure. [5,12] Male-only plasma donation strategies have decreased TRALI incidence by 40-50% since 2006. [2,11] However, TACO remains increasingly recognised as the leading cause of transfusion-related mortality in recent haemovigilance reports, reflecting both improved detection and aging patient populations. [6,7]

Risk Factors

Patient-Specific Factors:

Transfusion-Specific Factors:

• Rapid transfusion rate: TACO risk increases with rates > 2 mL/kg/hour [7,9]
• Large volume transfusion: > 4 units RBC in 24 hours increases TACO and TRALI risk [2]
• Platelet products: Higher bacterial contamination risk due to room temperature storage [13]
• Plasma-rich products: Higher TRALI risk from female donors (HLA antibodies) [11]
• Stored blood: Older blood (> 35 days) associated with increased cytokine accumulation [5]

---

Pathophysiology

Molecular and Cellular Mechanisms

Febrile Non-Haemolytic Transfusion Reaction (FNHTR)

FNHTR results from two primary mechanisms: [5,12]

1. Cytokine Accumulation: During blood component storage, white blood cells (both donor and residual recipient leukocytes) release pro-inflammatory cytokines including IL-1β, IL-6, IL-8, and TNF-α. These accumulate in the supernatant and trigger fever when transfused. Storage time correlates with cytokine levels.

2. Recipient Anti-Leukocyte Antibodies: Patients previously exposed to foreign HLA antigens (through pregnancy, transfusion, or transplantation) develop anti-HLA or anti-neutrophil antibodies. Upon subsequent transfusion, these antibodies bind donor leukocytes, triggering immune complex formation, complement activation, and cytokine release.

Temperature Rise Criteria: Defined as increase ≥1°C to a temperature ≥38°C during or within 4 hours of transfusion, in the absence of other pyrogenic stimuli. [3]

Allergic and Anaphylactic Reactions

Mild Allergic Reactions occur through IgE-mediated hypersensitivity to plasma proteins in transfused blood components. [14] Mast cell degranulation releases histamine, causing urticaria, pruritus, and mild bronchospasm without systemic involvement.

Anaphylactic Reactions are severe type I hypersensitivity reactions with two primary etiologies:

1. IgA Deficiency with Anti-IgA Antibodies: Patients with complete IgA deficiency (affects 1:500-700 individuals) may develop IgG or IgE antibodies against IgA. Subsequent exposure to IgA in donor plasma triggers massive mast cell and basophil activation. [14]

2. Haptoglobin Deficiency: Rare cause where patients develop antibodies to haptoglobin proteins.

Cascade: Antibody-antigen binding → mast cell/basophil degranulation → release of histamine, tryptase, leukotrienes → systemic vasodilation, increased vascular permeability, bronchospasm, and potential cardiovascular collapse.

Acute Haemolytic Transfusion Reaction (AHTR)

AHTR represents the most catastrophic immunologic transfusion reaction, typically caused by ABO incompatibility. [3,10]

Pathophysiologic Sequence:

1. Antibody-Mediated Cell Destruction: Pre-formed recipient IgM antibodies (anti-A, anti-B) bind incompatible donor RBC antigens immediately upon transfusion.

2. Complement Activation: IgM antibodies activate the classical complement pathway (C1→C2→C3→C4→C5-9 membrane attack complex), causing intravascular haemolysis within minutes.

3. Release of Haemolytic Products: Free haemoglobin, haem, and RBC membrane fragments are released into circulation, causing:

   • Haemoglobinaemia: Free Hb saturates haptoglobin binding capacity
   • Haemoglobinuria: Exceeded renal threshold for Hb reabsorption → dark urine
   • Renal injury: Direct tubular toxicity from haem pigments, vasoconstriction, tubular obstruction

4. Inflammatory Cascade: Complement fragments (C3a, C5a) act as anaphylatoxins, triggering:

   • Mast cell degranulation → hypotension
   • Neutrophil activation → tissue injury
   • Endothelial activation → vascular permeability

5. Coagulation Activation: Released tissue factor and RBC membrane phospholipids trigger disseminated intravascular coagulation (DIC):

   • Consumption of clotting factors (↓ fibrinogen, ↑ D-dimer)
   • Platelet activation and consumption
   • Microvascular thrombosis and bleeding diathesis

Critical Volume: As little as 10-15 mL of incompatible blood can trigger severe reactions; 200 mL can be fatal. [10]

Transfusion-Related Acute Lung Injury (TRALI)

TRALI is a form of acute respiratory distress syndrome (ARDS) occurring within 6 hours of transfusion, characterised by non-cardiogenic pulmonary oedema. [2,11,15]

Two-Hit Hypothesis:

First Hit - Patient predisposition:

• Underlying inflammatory state (sepsis, surgery, trauma)
• Neutrophil sequestration in pulmonary microvasculature
• Endothelial cell activation

Second Hit - Transfusion trigger via two mechanisms:

1. Antibody-Mediated TRALI (immune TRALI):

   • Donor anti-HLA class I/II or anti-neutrophil antibodies (HNA-1a, HNA-1b, HNA-2)
   • Antibodies bind cognate antigens on recipient neutrophils and pulmonary endothelium
   • Neutrophil activation and degranulation in pulmonary capillaries
   • Release of reactive oxygen species, proteases, and inflammatory mediators
   • Endothelial injury → increased capillary permeability → alveolar flooding

2. Non-Antibody-Mediated TRALI:

   • Biologically active lipids (lysophosphatidylcholines) accumulate during blood storage
   • Lipids prime neutrophils, lower activation threshold
   • Subsequent "second hit" triggers neutrophil-mediated lung injury

Pathologic Features:

• Diffuse alveolar damage
• Protein-rich pulmonary oedema (non-cardiogenic)
• Hyaline membrane formation
• Neutrophil infiltration in alveoli and interstitium

Clinical Timing: Typically occurs within 1-2 hours of transfusion, but can occur up to 6 hours post-transfusion. [11,15]

Transfusion-Associated Circulatory Overload (TACO)

TACO represents cardiogenic pulmonary oedema resulting from transfusion-induced volume expansion exceeding cardiac compensatory capacity. [2,7,9]

Pathophysiologic Mechanism:

1. Volume Challenge: Transfusion increases intravascular volume by 200-300 mL per unit RBC, 200-250 mL per unit plasma.

2. Cardiac Decompensation: In patients with limited cardiac reserve (systolic/diastolic dysfunction, valvular disease):

   • Increased preload exceeds Frank-Starling capacity
   • Left ventricular end-diastolic pressure (LVEDP) rises
   • Left atrial pressure increases → pulmonary venous hypertension

3. Pulmonary Capillary Hydrostatic Pressure Exceeds Oncotic Pressure:

   • When pulmonary capillary wedge pressure (PCWP) > 18-20 mmHg
   • Fluid transudation into alveolar interstitium and spaces
   • Cardiogenic pulmonary oedema develops

4. Neurohumoral Activation:

   • Increased atrial stretch → BNP/NT-proBNP release
   • Activation of renin-angiotensin-aldosterone system
   • Further sodium and water retention

Risk Amplification: Rapid transfusion rates, multiple units, and concurrent intravenous fluids exponentially increase TACO risk. [7,9]

Hypotensive Transfusion Reaction

Mechanism involves bradykinin accumulation in stored blood products, particularly in patients on ACE inhibitors (which inhibit bradykinin degradation). [16] Bradykinin causes systemic vasodilation and increased vascular permeability, leading to acute hypotension during transfusion.

Delayed Haemolytic Transfusion Reaction (DHTR)

Occurs 3-28 days post-transfusion when recipient develops secondary immune response (anamnestic response) to red cell antigens. [17]

Mechanism: Prior sensitisation (often undetectable at time of crossmatch) → transfusion re-exposes immune system → memory B cells proliferate → IgG antibody production (typically anti-Kidd, anti-Duffy, anti-Kell) → extravascular haemolysis via splenic macrophages phagocytosing antibody-coated RBCs.

Clinical Significance: More common in patients with sickle cell disease (up to 30% develop alloantibodies). [17]

---

Clinical Presentation

Acute Reactions (Within 24 Hours of Transfusion)

Febrile Non-Haemolytic Transfusion Reaction (FNHTR)

Classic Presentation:

• Temperature rise ≥1°C to ≥38°C
• Onset typically 30 minutes to 4 hours into transfusion
• Rigors (shaking chills) in 30-50% of cases
• Absence of other reaction features (no haemolysis, respiratory distress, hypotension)

Key Discriminators: Patient otherwise appears well between rigors; vital signs return to baseline after paracetamol; no progression of symptoms after transfusion cessation.

Diagnosis of Exclusion: Must rule out more serious reactions (bacterial contamination, haemolysis) before confirming FNHTR. [3,5]

Allergic Reactions (Mild)

Presentation:

• Urticaria (hives) - raised, erythematous, pruritic wheals
• Localised or generalised pruritus without rash
• Facial flushing
• No respiratory or cardiovascular involvement
• Onset: minutes to hours after transfusion start

Progression Risk: 1-2% of mild allergic reactions progress to anaphylaxis; monitor closely. [14]

Anaphylactic Reactions

Presentation: Rapid onset (usually within minutes of transfusion start)

Multi-System Involvement:

• Cardiovascular: Hypotension (> 30 mmHg drop), tachycardia, shock, loss of consciousness
• Respiratory: Bronchospasm, wheezing, stridor, dyspnoea, laryngeal oedema
• Cutaneous: Urticaria, angioedema (lips, tongue, periorbital), generalised erythema
• Gastrointestinal: Nausea, vomiting, abdominal cramping, diarrhoea
• Subjective: Sense of impending doom, metallic taste

Critical Volume: Can occur with as little as a few millilitres of transfused product. [14]

Life-Threatening Features: Laryngeal oedema causing airway obstruction, severe bronchospasm, cardiovascular collapse.

Acute Haemolytic Transfusion Reaction (AHTR)

Classic Triad: Fever, flank/back pain, haemoglobinuria [3,10]

Early Signs (during transfusion):

• Sense of "something wrong" or anxiety
• Fever and rigors (within 15-30 minutes)
• Pain at infusion site
• Chest tightness or substernal chest pain
• Lower back or flank pain (characteristic but not always present)
• Flushing

Progressive Signs:

• Hypotension and tachycardia (shock)
• Haemoglobinuria - dark red, brown, or "cola-coloured" urine (pathognomonic)
• Oliguria or anuria (acute kidney injury)
• Bleeding from venepuncture sites, surgical wounds (DIC)
• Jaundice (develops over hours)

In Anaesthetised Patients: May only manifest as:

• Unexplained hypotension
• Diffuse bleeding
• Haemoglobinuria
• Making diagnosis more challenging [10]

Severity Correlates with Volume: Reactions worsen with continued transfusion; early recognition and cessation crucial.

Transfusion-Related Acute Lung Injury (TRALI)

Diagnostic Criteria (2019 Consensus Definition): [1,11]

Required Features:

1. Acute onset within 6 hours of transfusion
2. Hypoxaemia: PaO₂/FiO₂ ≤300 mmHg or SpO₂ less than 90% on room air
3. Bilateral pulmonary infiltrates on chest radiograph
4. No evidence of left atrial hypertension (circulatory overload)

Clinical Presentation:

• Acute dyspnoea and tachypnoea
• Hypoxaemia often severe (PaO₂/FiO₂ less than 200 in 20-30% cases)
• Tachycardia
• Hypotension or normotension (NOT hypertension)
• Fever (38-40°C) in 50-80% of cases
• Frothy pink sputum (pulmonary oedema fluid)
• Cyanosis

Examination Findings:

• Bilateral inspiratory crackles
• Normal or low JVP (critical differentiating feature from TACO)
• No peripheral oedema
• Signs of respiratory distress: accessory muscle use, intercostal retractions

Timing: Median onset 1-2 hours, but can occur up to 6 hours post-transfusion. [2,11,15]

Severity Spectrum: 20-25% require mechanical ventilation; severe cases may progress to ARDS. [15]

Transfusion-Associated Circulatory Overload (TACO)

Clinical Presentation: [2,7,9]

Cardiovascular Features:

• Hypertension (> 20 mmHg increase in systolic BP) - key differentiator
• Tachycardia
• Elevated jugular venous pressure (JVP) - CRITICAL diagnostic feature
• S3 gallop on cardiac auscultation
• Peripheral oedema (especially if chronic fluid overload)

Respiratory Features:

• Acute dyspnoea
• Orthopnoea
• Tachypnoea
• Bilateral basal crackles progressing cephalad
• Hypoxaemia (usually less severe than TRALI)

Timing: Can occur during or within 6-12 hours of transfusion (later than TRALI average).

Response to Treatment: Rapid improvement with diuretics and upright positioning (unlike TRALI). [9]

Bacterial Contamination/Septic Transfusion Reaction

Presentation:

• High fever (> 39-40°C) and severe rigors
• Rapid onset (within minutes to 1 hour)
• Severe hypotension and shock (often refractory)
• Nausea, vomiting, diarrhoea
• Altered mental status
• Progression to septic shock and DIC

Highest Risk: Platelet products (stored at 20-24°C; bacterial growth) [13]

Common Organisms:

• Platelets: Staphylococcus epidermidis, Bacillus cereus
• Red cells: Yersinia enterocolitica, Serratia species (grow at 1-6°C)

Mortality: 15-25% if untreated. [13]

Hypotensive Transfusion Reaction

Presentation: [16]

• Isolated hypotension (> 30 mmHg drop in systolic BP)
• Onset within minutes of transfusion start
• No fever, respiratory symptoms, or urticaria
• Rapid resolution upon stopping transfusion

High-Risk Population: Patients on ACE inhibitors receiving leukoreduced blood through bedside leukoreduction filters.

Delayed Reactions (> 24 Hours Post-Transfusion)

Delayed Haemolytic Transfusion Reaction (DHTR)

Timing: 3-28 days post-transfusion (peak 7-14 days) [17]

Presentation:

• Mild fever (38-38.5°C)
• Anaemia more severe than expected (inadequate Hb increment)
• Mild jaundice
• Dark urine (haemoglobinuria less common than AHTR)
• Often asymptomatic; detected on routine blood tests

Laboratory Findings:

• Positive direct antiglobulin test (DAT)
• New red cell alloantibody detected
• Elevated unconjugated bilirubin and LDH
• Decreased haptoglobin

High-Risk Populations: Sickle cell disease (10-30% incidence), thalassaemia, chronically transfused patients. [17]

Red Flags Requiring Immediate Action

---

Clinical Examination

Initial Assessment - All Suspected Reactions

Vital Signs (repeat every 5-15 minutes until stable):

• Temperature (fever most common sign across reaction types)
• Blood pressure (hypotension in AHTR, anaphylaxis, sepsis; hypertension in TACO)
• Heart rate (tachycardia nearly universal except isolated FNHTR)
• Respiratory rate (tachypnoea in TRALI, TACO, anaphylaxis)
• Oxygen saturation (hypoxaemia in TRALI, TACO)

Conscious Level: GCS or AVPU; altered consciousness suggests severe reaction (shock, anaphylaxis, hypoxia).

Urine Colour: Examine catheter bag or ask patient to void - dark urine suggests haemolysis.

System-Specific Examination

Cardiovascular System

Inspection:

• Skin colour: pallor (anaemia, shock), flushing (anaphylaxis), cyanosis (hypoxia)
• Peripheral perfusion: capillary refill time > 2 seconds suggests shock

Jugular Venous Pressure:

• Elevated JVP: TACO (key discriminator)
• Normal/low JVP: TRALI, AHTR, anaphylaxis, FNHTR

Palpation:

• Peripheral pulses: volume, rate, rhythm
• Peripheral oedema: suggests TACO (but absence doesn't exclude)

Auscultation:

• Heart sounds: S3 gallop (ventricular dysfunction in TACO)
• Murmurs: may indicate underlying valvular disease predisposing to TACO

Respiratory System

Inspection:

• Respiratory rate and pattern
• Use of accessory muscles (sternocleidomastoid, intercostals)
• Paradoxical abdominal breathing (severe respiratory distress)

Auscultation:

• Bilateral basal crackles: TACO (gravity-dependent distribution)
• Bilateral widespread crackles: TRALI (diffuse alveolar involvement)
• Wheeze: anaphylaxis (bronchospasm), asthma exacerbation
• Reduced air entry: severe TRALI/TACO, pleural effusion

Percussion:

• Stony dull: pleural effusion (may accompany severe TACO)

Skin and Mucous Membranes

Inspection:

• Urticaria: raised, erythematous wheals - allergic reaction
• Angioedema: non-pitting swelling of lips, tongue, periorbital regions - anaphylaxis
• Flushing: generalised erythema - allergic reaction, AHTR
• Petechiae, purpura, ecchymoses: DIC (AHTR, severe sepsis)
• Jaundice: haemolysis (takes hours to develop)
• Bleeding from IV sites: DIC

Palpation:

• Skin temperature: cool peripheries suggest shock

Abdominal Examination

Palpation:

• Flank tenderness or back pain: characteristic of AHTR (though not always present)
• Hepatosplenomegaly: chronic haemolysis, underlying haematologic disorder

Temperature

Pattern Recognition:

• Mild fever 38-38.5°C: FNHTR (most likely)
• High fever > 39°C with rigors: AHTR, bacterial contamination (urgent exclusion needed)
• Fever with hypotension: NEVER assume FNHTR; investigate for AHTR or sepsis

Examination Findings: Differential Diagnosis Guide

---

Investigations

Immediate Bedside Actions (Before Laboratory Tests)

Essential Laboratory Investigations

Immediate Samples (within 15-30 minutes): [3,18]

Sample Timing: Draw samples from arm opposite to transfusion site if possible (avoid contamination with transfused blood).

Haemolysis Investigation Panel

Confirmation of Intravascular Haemolysis: [3,10]

Interpretation:

• Pink/red plasma on centrifuged sample = free haemoglobin (intravascular haemolysis)
• ↓ haptoglobin alone can occur with extravascular haemolysis (DHTR)
• Positive urine dipstick for "blood" with NO red cells on microscopy = haemoglobinuria

Antibody Identification

Immunohaematology Workup:

1. Repeat ABO/Rh typing: Detect clerical error or incorrect historical typing
2. Antibody screen: Identify presence of unexpected red cell antibodies
3. Antibody identification panel: Determine specificity (anti-K, anti-Fya, anti-Jka, etc.)
4. Crossmatch: Test patient serum against donor unit - incompatibility confirms immune reaction
5. Donor antibody testing: Check donor for HLA/HNA antibodies (TRALI investigation)

Extended Typing: In alloimmunised patients (sickle cell, thalassaemia), perform extended phenotyping for minor antigens (Rh, Kell, Duffy, Kidd, MNS systems). [17]

TRALI vs TACO Differentiation

Diagnostic Challenges: Both present with acute dyspnoea and bilateral pulmonary infiltrates within 6 hours; differentiation crucial for management. [2,7,9,11]

BNP/NT-proBNP Cutoffs: [7,9]

• TACO: NT-proBNP > 1,200 pg/mL (or increase > 50% from pre-transfusion)
• TRALI: NT-proBNP typically less than 500 pg/mL or unchanged from baseline

Point-of-Care Ultrasound (POCUS):

• Lung ultrasound: B-lines (comet tails) in both conditions
• Cardiac ultrasound: LV systolic/diastolic dysfunction, dilated IVC suggests TACO

Response to Diuretics: TACO improves within 1-2 hours; TRALI shows no improvement (therapeutic trial can aid diagnosis). [9]

Bacterial Contamination Investigation

Urgent Microbiology: [13]

1. Patient blood cultures: Aerobic and anaerobic bottles × 2 sets from separate sites
2. Blood bag culture:
   • Culture residual blood in bag
   • Culture port site swabs
   • Direct Gram stain of bag contents
3. Rapid detection: Some centres use automated bacterial detection systems (results in 24 hours vs 5-7 days for culture)

High-Yield Organisms:

• Gram-positive (platelets): Staphylococcus, Bacillus, Streptococcus
• Gram-negative (RBCs): Yersinia, Serratia, Pseudomonas

Imaging Studies

Chest Radiograph (all respiratory reactions): [2,11]

• TRALI: Bilateral diffuse alveolar infiltrates, normal cardiac silhouette
• TACO: Bilateral infiltrates, cardiomegaly, pleural effusions, Kerley B lines, cephalization
• Timing: Changes visible within 1-2 hours; TRALI typically improves within 48-96 hours

CT Chest (if diagnosis uncertain):

• Ground-glass opacification (both TRALI and TACO)
• Interlobular septal thickening (more common in TACO)

Echocardiography:

• Indications: Differentiate TRALI vs TACO when clinical features equivocal
• TACO findings: LV systolic dysfunction (EF less than 45%), diastolic dysfunction (E/e' > 15), elevated estimated RA pressure
• TRALI findings: Normal LV systolic function, may have RV strain if severe

Investigation of Blood Unit and Donor

Mandatory Actions (Blood Bank/Transfusion Service): [3,8]

1. Clerical check: Review entire transfusion chain (sample labelling, unit selection, patient identification)
2. Bag inspection: Visual check for haemolysis, clots, discolouration, bacterial contamination
3. Donor testing:
   • HLA antibody screen (female donors if TRALI suspected)
   • HNA antibody screen
   • Repeat ABO/Rh
4. Donor notification: Quarantine additional units from same donor
5. Lookback investigation: Trace other recipients of components from same donation

Monitoring During Investigation

Continuous Monitoring:

• Vital signs: every 5 minutes if unstable, every 15 minutes once stable
• Urine output: hourly (target > 0.5-1 mL/kg/hour to prevent AKI)
• Fluid balance: strict input-output charting

Serial Laboratory Tests (in moderate-severe reactions):

• FBC: 4-6 hourly (monitor for ongoing haemolysis, DIC)
• Coagulation: 4-6 hourly if DIC suspected
• Renal function: 12-24 hourly
• Haemolysis markers: 6-12 hourly until improving

---

Classification & Staging

Acute Transfusion Reactions (Within 24 Hours)

Classification by Mechanism and Clinical Features:

Delayed Transfusion Reactions (> 24 Hours)

Severity Grading (Standardised Haemovigilance Classification)

Grade 1 (Mild):

• Minimal symptoms
• No intervention required or simple intervention only (e.g., paracetamol for mild fever)
• Full recovery expected

Examples: Isolated mild urticaria, temperature rise to 38.5°C without rigors

Grade 2 (Moderate):

• Moderate symptoms
• Requires intervention (medication, transfusion cessation)
• May require observation/monitoring
• Full recovery expected

Examples: FNHTR with rigors, moderate allergic reaction requiring antihistamines

Grade 3 (Severe - Life-Threatening):

• Severe symptoms threatening life or organ function
• Requires urgent intervention
• May require ICU admission
• Risk of permanent sequelae

Examples: AHTR, TRALI requiring ventilation, anaphylaxis, severe TACO

Grade 4 (Fatal):

• Reaction resulted in patient death
• Death attributed primarily to transfusion reaction

Imputability Assessment (Causality)

International Haemovigilance Network (IHN) Criteria:

Definite:

• Conclusive evidence (e.g., ABO incompatibility confirmed, positive bacterial culture from bag)
• No other explanation

Probable:

• Strong temporal association
• Clinical and laboratory findings consistent
• No other likely explanation

Possible:

• Reasonable temporal association
• Could be explained by other factors
• Insufficient evidence to confirm

Unlikely:

• Temporal association present but weak
• More likely explained by other causes

Not Related:

• Conclusive evidence of alternative cause
• No plausible transfusion link

Special Populations

Sickle Cell Disease: [17]

• DHTR incidence up to 30% (vs less than 1% general population)
• Hyperhemolysis syndrome: severe anaemia, bystander haemolysis of native RBCs
• Alloimmunisation rates 10-30% (require extended antigen matching)

Paediatric Patients:

• TACO risk higher due to smaller circulating volumes
• Adjusted transfusion volumes: 10-15 mL/kg RBC, 10-20 mL/kg plasma
• Slower transfusion rates recommended (over 2-4 hours)

Cardiac Disease:

• TACO incidence up to 11% in patients with EF less than 40%
• Require pre-transfusion diuretic consideration
• Slower transfusion rates essential

---

Management

Universal Immediate Actions - ALL Suspected Reactions

The "STOP-ASSESS-NOTIFY-INVESTIGATE" Protocol: [3,18]

DO NOT:

• Discard blood bag or giving set (required for investigation)
• Restart transfusion before cause identified
• Delay treatment while awaiting investigations

Reaction-Specific Management

Febrile Non-Haemolytic Transfusion Reaction (FNHTR)

Diagnosis of Exclusion: Must rule out AHTR, bacterial contamination before confirming FNHTR. [3,5]

Management:

1. Stop transfusion, take vital signs, check ID labels

2. Investigations: Blood cultures, repeat group/crossmatch, DAT, haemolysis screen

3. Symptomatic treatment:

   • Paracetamol: 1 g PO/IV (reduces fever, patient comfort)
   • Pethidine 25-50 mg IV (if severe rigors): Acts on shivering centre

4. Observation: Monitor vital signs every 15 minutes until stable and for 1 hour after

Transfusion Resumption:

• Only if: (1) No evidence haemolysis, (2) No bacterial contamination, (3) Temperature settling, (4) Patient otherwise stable
• Use: Same unit if investigation negative OR new unit if uncertainty
• Monitor: Closely for recurrence or progression

Prevention of Recurrence:

• Leukoreduction: Reduces FNHTR by 50-75% [12]
• Pre-medication: NOT routinely recommended (masks serious reactions)
  • Consider only if recurrent FNHTR despite leukoreduction
  • Paracetamol 1 g PO 30 minutes pre-transfusion

Allergic Reactions (Mild Urticarial)

Management: [3,14]

1. Stop transfusion, assess patient

2. Antihistamine:

   • Chlorphenamine 10 mg IV slowly OR
   • Cetirizine 10 mg PO (non-sedating alternative)

3. Observation: 30-60 minutes; monitor for progression to anaphylaxis

Transfusion Resumption:

• If symptoms resolve completely: May cautiously restart SAME unit
• Slow rate: Resume at 25-50% original rate, monitor closely
• If symptoms recur or worsen: STOP, treat as anaphylaxis

Prevention:

• Washed blood products: Remove plasma proteins (for recurrent reactions)
• Pre-medication: NOT recommended routinely (insufficient evidence, may mask anaphylaxis)

Anaphylactic Reactions

Life-Threatening Emergency: Requires immediate resuscitation. [3,14]

Immediate Management (First 5 Minutes):

1. STOP transfusion immediately

2. IM Adrenaline (FIRST-LINE, life-saving):

   • Adults: 0.5 mg (500 mcg) = 0.5 mL of 1:1,000 IM into anterolateral thigh
   • Children: 10 mcg/kg (max 500 mcg)
   • Repeat every 5 minutes if no improvement (up to 3 doses)

3. Lie patient flat, raise legs (improves venous return)

   • Exception: Severe respiratory distress → semi-recumbent

4. High-flow oxygen: 15 L/min via non-rebreather mask, target SpO₂ > 94%

5. IV fluid resuscitation:

   • 0.9% saline 500-1,000 mL rapid bolus (adults)
   • Repeat boluses as needed for persistent hypotension
   • Massive volumes may be required (distributive shock)

6. Call for help: Crash team/MET call, senior support

Secondary Management (First 15-30 Minutes):

7. Antihistamines (adjunct, NOT first-line):

   • Chlorphenamine 10 mg IV slowly (H1-blocker)
   • Ranitidine 50 mg IV (H2-blocker) - optional

8. Corticosteroids (prevent biphasic reaction, though evidence limited):

   • Hydrocortisone 200 mg IV (adults)
   • Effect delayed (hours), NOT for acute management

9. Bronchodilators (if bronchospasm):

   • Salbutamol nebuliser 5 mg (can repeat)
   • Ipratropium nebuliser 500 mcg (additive effect)

10. Refractory Hypotension:

    • IV adrenaline infusion: 0.05-0.1 mcg/kg/min, titrate to BP
    • Requires ICU-level care, continuous monitoring

Investigations:

• Mast cell tryptase: Serum level within 1-2 hours of reaction (confirms anaphylaxis)
• IgA levels: Screen for IgA deficiency (send within 24-48 hours)

Observation:

• Minimum 6-12 hours (risk of biphasic reaction in 5-20% cases)
• ICU admission if severe reaction or refractory symptoms

Prevention:

• IgA-deficient patients:
  • Use washed RBCs and platelets (remove all plasma)
  • Use IgA-deficient donor plasma if plasma required (rare)
• Alert card/bracelet: Patient should carry identification

DO NOT restart transfusion - absolute contraindication.

Acute Haemolytic Transfusion Reaction (AHTR)

Medical Emergency: High mortality (10-40%) if not managed aggressively. [3,10]

Immediate Resuscitation (First 30 Minutes):

1. Stop Transfusion + Secure Airway/Breathing/Circulation

2. Fluid Resuscitation (CRITICAL to prevent acute kidney injury):

• Goal: Maintain urine output > 1-1.5 mL/kg/hour (> 100 mL/hour in adults)
• 0.9% saline 1-2 L rapid IV bolus (adults), then:
  • Continue 150-200 mL/hour IV maintenance
  • Titrate to urine output

3. Insert Urinary Catheter:

• Monitor hourly urine output (essential endpoint)
• Observe for haemoglobinuria (dark urine)

4. Notify Blood Bank Urgently:

• Request immediate investigation
• Hold further transfusions until cause identified

Specific Therapies:

5. Alkalinise Urine (controversial, some guidelines recommend):

• Sodium bicarbonate 50-100 mEq IV in fluids
• Target: Urine pH > 7.0
• Rationale: Reduces haem precipitation in renal tubules (though evidence limited)

6. Diuresis (ONLY if adequate intravascular volume):

• Furosemide 40-80 mg IV if fluid-replete but oliguria persists
• Goal: Achieve urine output > 200 mL/hour
• Monitor: Avoid hypovolaemia (worsens renal injury)

7. Vasopressor Support (if shock despite fluids):

• Noradrenaline 0.05-0.5 mcg/kg/min IV infusion
• Requires ICU admission, invasive monitoring

Management of Complications:

Disseminated Intravascular Coagulation (DIC):

• Occurs in 20-40% of severe AHTR [10]
• Diagnosis: ↓platelets, ↓fibrinogen, ↑PT/APTT, ↑D-dimer
• Treatment:
  • "Platelets: Transfuse if less than 50 × 10⁹/L and bleeding (use ABO-compatible units)"
  • "Fresh Frozen Plasma: 15-20 mL/kg if coagulopathy and bleeding"
  • "Cryoprecipitate: If fibrinogen less than 1.5 g/L"
  • Treat underlying cause (stop haemolysis)

Acute Kidney Injury:

• Occurs in 30-50% of AHTR [10]
• Mechanisms: Haem toxicity, hypotension, DIC-related microvascular thrombosis
• Management:
  • Aggressive fluid resuscitation (as above)
  • Avoid nephrotoxins (NSAIDs, aminoglycosides, contrast)
  • "Renal replacement therapy: Haemodialysis or haemofiltration if:"
    • Severe hyperkalaemia (K⁺ > 6.5 mmol/L)
    • Refractory acidosis (pH less than 7.1)
    • Pulmonary oedema (fluid overload)
    • Uraemic complications

Ongoing Monitoring:

• Vital signs: Continuous in ICU or every 15 minutes in HDU
• Urine output: Hourly
• FBC, coagulation: 4-6 hourly (monitor DIC)
• U&E, creatinine: 6-12 hourly (monitor AKI)
• Haemolysis markers: Daily until resolving

Transfusion Requirement:

• Further transfusion: May be required if severe anaemia develops
• Use ONLY ABO-COMPATIBLE, crossmatch-compatible units
• Await blood bank advice before transfusing

ICU Admission: Indicated for shock, DIC, severe AKI, multiorgan dysfunction.

Transfusion-Related Acute Lung Injury (TRALI)

Supportive Care Cornerstone: No specific therapy; mortality 5-10%. [2,11,15]

Immediate Management:

1. Stop Transfusion

2. Oxygen Therapy:

• High-flow oxygen 15 L/min via non-rebreather mask
• Target: SpO₂ 92-96% (or 88-92% if COPD)
• Escalate if inadequate:
  • "High-flow nasal cannula (HFNC): 40-60 L/min, FiO₂ 0.6-1.0"
  • "Non-invasive ventilation (NIV): CPAP or BiPAP"
  • "Mechanical ventilation: if severe hypoxaemia (PaO₂/FiO₂ less than 150) or respiratory failure"

3. Lung-Protective Ventilation (if intubated):

• Tidal volume: 6 mL/kg ideal body weight (prevent ventilator-induced lung injury)
• Plateau pressure: less than 30 cmH₂O
• PEEP: 5-15 cmH₂O (optimise recruitment)
• FiO₂: Lowest to maintain SpO₂ 88-95%

4. Fluid Management (CRITICAL difference from TACO):

• DO NOT give diuretics (not volume overload; may worsen hypotension)
• Cautious fluid resuscitation: Balance haemodynamics vs worsening oedema
  • "If hypotensive: Small boluses (250-500 mL) 0.9% saline"
  • "If normotensive/hypertensive: Restrict fluids to maintenance"
• Haemodynamic monitoring: Consider arterial line ± central line

5. Vasopressor Support (if hypotensive despite fluids):

• Noradrenaline 0.05-0.3 mcg/kg/min IV
• Avoid excessive fluid administration

Adjunct Therapies (limited evidence):

6. Corticosteroids: NOT recommended routinely (no proven benefit in RCTs)

• Consider if severe, refractory hypoxaemia (methylprednisolone 1-2 mg/kg/day)

7. Diuretics: ONLY if concomitant volume overload (e.g., pre-existing cardiac failure)

Monitoring:

• ABG: 1-4 hourly (monitor oxygenation, acid-base)
• Chest X-ray: Daily (expect improvement within 48-96 hours)
• Haemodynamics: Continuous if invasive monitoring in situ

ICU Admission:

• Indications: Hypoxia requiring > 60% FiO₂, respiratory distress, hypotension, mechanical ventilation

Prognosis:

• Most patients improve within 48-96 hours (spontaneous resolution) [15]
• Mechanical ventilation required: 20-25% of cases
• Mortality: 5-10% (lower if pure TRALI; higher if underlying critical illness)

Transfusion After TRALI:

• No absolute contraindication to future transfusion
• Avoid implicated donors: Blood bank will investigate and defer donors with HLA/HNA antibodies
• Leukoreduced components: May reduce recurrence risk

Transfusion-Associated Circulatory Overload (TACO)

Management: Treat as acute cardiogenic pulmonary oedema. [2,7,9]

Immediate Interventions:

1. Stop Transfusion

2. Position Patient Upright:

• Sit patient at 45-90 degrees (reduces venous return, improves diaphragmatic excursion)

3. Oxygen Therapy:

• High-flow oxygen 15 L/min via non-rebreather mask
• Target: SpO₂ 94-98%

4. IV Diuretic (FIRST-LINE pharmacotherapy):

• Furosemide 40-80 mg IV bolus (adults)
  • Double home dose if already on diuretics
  • Expect diuresis within 30-60 minutes
• Repeat or increase dose if inadequate response:
  • Furosemide 80-120 mg IV at 1-2 hours
  • Or furosemide infusion 5-10 mg/hour

5. Monitor Fluid Balance:

• Strict input-output chart
• Daily weights (if recurrent TACO risk)
• Target: Negative balance of 500-1,000 mL/day

Adjunct Therapies:

6. Vasodilators (if hypertensive and pulmonary oedema):

• GTN (glyceryl trinitrate):
  • "Sublingual: 400-800 mcg (immediate effect)"
  • "IV infusion: 1-10 mg/hour (if severe)"
• Mechanism: Venodilation reduces preload

7. Non-Invasive Ventilation:

• CPAP (Continuous Positive Airway Pressure): 5-10 cmH₂O
  • "Indications: Severe dyspnoea, hypoxia despite high-flow O₂, respiratory distress"
  • "Benefits: Reduces preload and afterload, improves gas exchange, reduces intubation need"
• BiPAP: Alternative to CPAP

8. Invasive Ventilation:

• Rare requirement (most respond to diuretics + CPAP)
• Indications: Respiratory arrest, severe hypoxaemia refractory to NIV, exhaustion

Monitoring:

• Vital signs: Every 15 minutes initially, then hourly once stable
• Fluid balance: Continuous charting
• Urine output: Hourly (assess diuretic response)
• Repeat BNP: If diagnostic uncertainty (should decrease with treatment)
• Chest X-ray: 12-24 hours (expect improvement)

Prognosis:

• Rapid response expected: Most improve within 1-4 hours
• Lack of improvement: Consider alternative diagnosis (TRALI, cardiac ischaemia, pneumonia)

Prevention of Future TACO:

Transfusion Strategy:

• Single-unit transfusions: Reassess after each unit (restrictive approach) [19]
• Slow transfusion rate: ≤1 mL/kg/hour (over 3-4 hours per RBC unit)
• Diuretic co-administration: Furosemide 20-40 mg IV with alternate units (in high-risk patients)

Patient Selection:

• Avoid unnecessary transfusions: Adhere to restrictive thresholds
  • "Stable patients: Hb less than 70 g/L"
  • "Cardiac patients: Hb less than 80 g/L"
• Optimise cardiac function: Ensure euvolaemic before transfusion

Hypotensive Transfusion Reaction

Management: [16]

1. Stop transfusion → hypotension typically resolves within minutes
2. IV fluids: 0.9% saline 250-500 mL bolus if symptomatic
3. Observation: Monitor BP every 5 minutes until stable

Transfusion Resumption:

• New blood unit: Do NOT use original unit
• Slower rate: 50% of previous rate
• Monitor closely: BP every 15 minutes

Prevention:

• Avoid bedside leukoreduction filters in patients on ACE inhibitors (bradykinin accumulation)
• Pre-storage leukoreduction: Preferred method

Bacterial Contamination/Septic Transfusion Reaction

Life-Threatening Emergency: Requires immediate antibiotics and resuscitation. [13]

Immediate Management:

1. Stop Transfusion

2. Resuscitation (Sepsis Six):

• High-flow oxygen: 15 L/min
• IV fluid bolus: 500-1,000 mL crystalloid (repeat as needed)
• Blood cultures: Two sets from separate sites BEFORE antibiotics
• IV antibiotics: Broad-spectrum, within 1 hour (see below)
• Lactate: Measure (marker of tissue hypoperfusion)
• Urine output: Monitor (catheterise if shocked)

3. Empirical Antibiotics (immediate, do NOT wait for microbiology):

• Platelet-associated sepsis (Gram-positive likely):

  • Vancomycin 15-20 mg/kg IV (MRSA cover) PLUS
  • Piperacillin-tazobactam 4.5 g IV (Gram-negative cover)

• RBC-associated sepsis (Gram-negative likely):

  • Piperacillin-tazobactam 4.5 g IV OR
  • Meropenem 1 g IV (if penicillin allergy or severe sepsis)

4. Blood Bank Notification:

• Return blood bag urgently: Gram stain and culture
• Quarantine co-components: Trace other units from same donation

5. Vasopressor Support (if shock despite fluids):

• Noradrenaline 0.05-0.5 mcg/kg/min IV
• Requires ICU admission

6. ICU Admission:

• Indications: Septic shock, organ dysfunction, lactate > 4 mmol/L

Microbiological Investigation:

• Patient blood cultures: Aerobic + anaerobic × 2 sets
• Blood bag culture: Residual bag contents
• Gram stain: Immediate microscopy of bag contents (can guide initial antibiotic choice)

Antibiotic Adjustment:

• Revise based on Gram stain/culture results (usually available 24-48 hours)
• Typical organisms:
  • "Platelets: Staph epidermidis, Staph aureus, Bacillus cereus"
  • "RBCs: Yersinia enterocolitica, Serratia marcescens"

Prognosis:

• Mortality: 15-25% if untreated; less than 5% with prompt recognition and treatment [13]

Delayed Haemolytic Transfusion Reaction (DHTR)

Usually Mild and Self-Limiting: [17]

Management:

1. Confirm Diagnosis:

• Positive DAT + new red cell antibody + evidence of haemolysis

2. Supportive Care:

• Hydration: Oral or IV fluids (maintain urine output)
• Folate supplementation: 5 mg daily (increased RBC turnover)
• Monitor: FBC, bilirubin, LDH, haptoglobin every 2-3 days until stable

3. Blood Bank Referral:

• Extended phenotyping: Identify all red cell antigens
• Future transfusions: Provide antigen-negative units (prevent recurrence)

4. Severe Cases (rare):

• Hyperhemolysis syndrome (sickle cell disease): Severe anaemia, bystander haemolysis
  • Avoid further transfusion (may worsen haemolysis)
  • "Immunosuppression: Corticosteroids (prednisolone 1 mg/kg), IVIG (1 g/kg)"
  • "Eculizumab: Case reports in refractory cases (complement inhibitor)"

Prevention:

• Extended red cell matching: Match for Rh (C,c,E,e), Kell, Duffy, Kidd in high-risk patients (sickle cell, thalassaemia, chronically transfused) [17]

---

Complications

Acute Haemolytic Transfusion Reaction Complications

TRALI Complications

• Acute Respiratory Distress Syndrome (ARDS): 15-20% develop criteria-meeting ARDS [15]
• Prolonged mechanical ventilation: Average 3-7 days in those requiring intubation
• Secondary infections: Hospital-acquired pneumonia risk with ventilation
• Death: 5-10% mortality rate [2,15]

TACO Complications

• Acute myocardial infarction: Precipitated by increased cardiac workload in susceptible patients
• Respiratory failure: Requiring mechanical ventilation (rare if treated promptly)
• Death: 1-5% mortality, higher in elderly and those with severe cardiac dysfunction [7]

Anaphylaxis Complications

• Biphasic reaction: 5-20% experience second wave of symptoms 4-12 hours later (requires prolonged observation) [14]
• Hypoxic brain injury: If prolonged hypotension or airway obstruction
• Death: 1-2% mortality if prompt adrenaline not given

Bacterial Contamination Complications

• Septic shock: Refractory hypotension requiring vasopressor support
• Multiorgan dysfunction: Acute kidney injury, ARDS, hepatic dysfunction, DIC
• Death: 15-25% mortality without prompt antibiotic therapy [13]

---

Prognosis & Outcomes

Short-Term Outcomes by Reaction Type

Factors Influencing Prognosis

Poor Prognostic Indicators:

• Large volume of incompatible blood transfused (AHTR): > 200 mL associated with > 50% mortality [10]
• Delay in recognition and treatment: Each hour delay increases mortality
• Pre-existing organ dysfunction: Renal, cardiac, or hepatic impairment worsens outcomes
• Advanced age: > 70 years associated with 2-3× mortality risk
• Immunosuppression: Increases infection risk, impairs recovery

Positive Prognostic Indicators:

• Immediate transfusion cessation: Limits antigen/volume exposure
• Early aggressive treatment: Especially fluid resuscitation in AHTR
• Absence of hypotension: Normotensive reactions generally benign

Long-Term Outcomes

Alloimmunisation:

• Incidence after reaction: Significantly increased (10-30% in those with FNHTR due to HLA exposure) [5]
• Clinical impact: Future transfusion challenges, platelet refractoriness, difficulty finding compatible blood
• Management: Extended phenotyping, maintain antibody records

Renal Function:

• AHTR survivors: 10-20% have persistent renal impairment (eGFR reduction)
• Chronic kidney disease: May develop if severe AKI

Recurrence Risk:

• FNHTR: 10-20% recurrence if leukoreduced; less than 5% with washed components
• Allergic: 30-50% recurrence without preventive measures (washed products)
• TRALI: Low recurrence risk if causative donor identified and deferred
• TACO: High recurrence risk (> 50%) without preventive transfusion strategy

Psychological Impact:

• Transfusion anxiety: Some patients develop fear of future transfusions
• Counselling: Important for severe reactions, especially if future transfusions likely

Haemovigilance Data

UK SHOT Reports (Serious Hazards of Transfusion): [8]

• Transfusion-related mortality: 20-30 deaths annually in UK
• Leading causes: TACO (40%), TRALI (20%), AHTR (15%)
• Preventable deaths: 70-80% (mostly due to identification errors or failure to recognise reactions)

Quality Metrics:

• Time to transfusion cessation: Target less than 5 minutes of symptom onset
• Time to treatment: Adrenaline within 5 minutes for anaphylaxis, fluids within 15 minutes for AHTR
• Investigation completion: Full workup within 24 hours

---

Prevention Strategies

System-Level Interventions

Patient Identification (prevents 70% of fatal AHTR): [3,8]

1. Two-Person Bedside Check:

   • Verify patient identity using TWO identifiers (name + date of birth)
   • Check against patient ID band AND blood unit label
   • Perform immediately before starting transfusion

2. Electronic Patient Identification:

   • Barcode scanning of patient wristband and blood unit
   • Reduces error rate by 90% compared to manual checks
   • Increasingly adopted in high-volume centres

3. Positive Patient Identification:

   • Ask patient to state name and date of birth (if conscious)
   • NEVER rely on bed labels or verbal confirmation alone

Correct Blood Component Selection:

4. Sample Labelling:

   • Label blood samples AT THE BEDSIDE immediately after phlebotomy
   • Include: Full name, date of birth, hospital number, date, time, phlebotomist signature
   • Pre-labelled samples unacceptable (high error rate)

5. Crossmatch Validity:

   • Use fresh sample (less than 72 hours) if recent transfusion or pregnancy
   • Electronic crossmatch only if no atypical antibodies

6. Right Blood to Right Patient:

   • Check ABO/Rh compatibility at bedside
   • Final check: Patient ID = Blood unit label = Compatibility label

Blood Component Modifications

Universal Leukoreduction: [5,12]

• Method: Remove white blood cells to less than 5 × 10⁶ per unit
• Prevents: FNHTR (50-75% reduction), CMV transmission, HLA alloimmunisation
• Standard: Mandatory in many countries (UK, Canada, European nations)

Male-Only Plasma Donors (TRALI prevention): [11]

• Rationale: Multiparous women develop HLA antibodies; primary cause of antibody-mediated TRALI
• Implementation: Use plasma from male donors or nulliparous female donors
• Impact: 40-50% reduction in TRALI incidence since 2006

Bacterial Detection Systems: [13]

• Platelet bacterial screening: Automated culture systems (detects bacteria within 24 hours)
• Implementation: Increasingly standard for platelets (highest contamination risk)
• Impact: Reduces septic reactions by 50-70%

Washed Blood Components:

• Indications: Recurrent allergic reactions, IgA deficiency, severe protein allergies
• Method: Centrifugation and saline washing removes > 95% plasma proteins
• Products: Washed RBCs, washed platelets
• Limitations: Shorter shelf-life (24 hours), expensive, limited availability

Irradiated Blood Components (prevent TA-GVHD):

• Indications: Immunocompromised patients (haematologic malignancies, stem cell transplant, chemotherapy, congenital immunodeficiency)
• Method: 25-50 Gy gamma irradiation inactivates donor T-lymphocytes
• Impact: Eliminates TA-GVHD risk

Transfusion Practice Optimisation

Restrictive Transfusion Thresholds: [19]

• Evidence: RCTs demonstrate non-inferiority of restrictive vs liberal transfusion
• Recommended thresholds:
  • "Stable patients: Hb less than 70 g/L"
  • "Cardiac disease/acute coronary syndrome: Hb less than 80 g/L"
  • "Actively bleeding: Clinical assessment, not Hb alone"
• Impact: Reduces transfusion volume → reduces TACO risk

Single-Unit RBC Transfusion Policy:

• Principle: Transfuse one unit, reassess, transfuse second unit ONLY if indicated
• Benefits: Prevents over-transfusion, reduces TACO risk by 40%
• Exceptions: Active haemorrhage requiring massive transfusion

Slow Transfusion Rates in High-Risk Patients: [9]

• Rate: ≤1 mL/kg/hour (approximately 3-4 hours per RBC unit in adults)
• High-risk patients: Age > 70, cardiac failure (EF less than 40%), renal failure (eGFR less than 30)
• Monitoring: Vital signs every 15 minutes for first hour, then hourly

Pre-Transfusion Diuretics (controversial): [9]

• Rationale: Reduce circulating volume before transfusion
• Evidence: Mixed; some studies show TACO reduction, others no benefit
• Current guidance:
  • "Consider: Furosemide 20-40 mg IV with alternate RBC units in high-risk patients (cardiac failure, severe anaemia Hb less than 60 g/L)"
  • "NOT routine: Insufficient evidence for universal recommendation"

Patient-Specific Strategies

High-Risk Groups:

Transfusion History Review:

• Prior reactions: Document type, severity, management
• Antibody screen: Review historical antibodies (even if currently negative—can wane)
• Phenotype database: Maintain extended red cell phenotype in chronically transfused patients

Education and Training

Staff Competency:

• Mandatory training: All staff involved in transfusion chain (phlebotomy, portering, nursing, medical)
• Competency assessment: Annual revalidation on identification procedures, transfusion administration
• Simulation: Transfusion reaction drills (improves response time)

Patient Education:

• Pre-transfusion counselling: Explain signs/symptoms to report immediately
• Symptom card: Provide written instructions ("Tell nurse immediately if you feel unwell")

Haemovigilance and Reporting

Mandatory Reporting: [8]

• All reactions: Report to blood bank and national haemovigilance system (e.g., SHOT UK, TACO USA)
• Near misses: Report incorrect blood component prepared/issued (even if not transfused)
• Purpose: Identify trends, implement system improvements

Root Cause Analysis:

• Serious reactions: Conduct RCA to identify system failures
• Action plans: Implement changes to prevent recurrence

Lookback Investigations:

• Transfusion-transmitted infection: Trace recipients of blood components from infected donor
• TRALI: Trace other recipients of components from implicated donor (test for HLA/HNA antibodies)

---

Evidence & Guidelines

Major International Guidelines

1. British Committee for Standards in Haematology (BCSH) - 2012: [3]

• Title: Guideline on the investigation and management of acute transfusion reactions
• Key Recommendations:
  • All acute reactions require immediate transfusion cessation
  • Standard investigation protocol including repeat group/crossmatch, DAT, haemolysis screen, bacterial cultures
  • TRALI vs TACO differentiation using BNP and clinical features
• Evidence Level: Grade A (high-quality RCTs) for key interventions; Grade C (expert opinion) for investigation protocols

2. American Association of Blood Banks (AABB) - 2018: [18]

• Recommendations:
  • Restrictive transfusion thresholds (Hb less than 70 g/L stable patients, less than 80 g/L cardiac disease)
  • Single-unit RBC transfusion strategy
  • Leukoreduction for all blood components
• Evidence: Strong recommendation, moderate-quality evidence

3. TRALI Consensus Definition - 2019: [1]

• Vlaar et al., Transfusion 2019 - International consensus on diagnostic criteria
• Criteria: Acute onset ≤6 hours, PaO₂/FiO₂ ≤300, bilateral infiltrates, no left atrial hypertension
• Impact: Standardised diagnosis for research and haemovigilance

Key Evidence and Landmark Studies

TRALI Pathophysiology and Outcomes: [2,15]

• Semple et al., Blood 2019: Comprehensive review of TRALI and TACO mechanisms, biomarkers, and differentiation strategies
• Toy et al., Ann Am Thorac Soc 2022: 36-year review of TRALI progress; documents impact of male-plasma-only policy

TACO Biomarkers and Diagnosis: [7,9]

• Klanderman et al., Transfusion 2019: Systematic review of TACO diagnostic biomarkers; BNP/NT-proBNP sensitivity 81%, specificity 89%
• Tobian et al., Transfusion 2008: Landmark study demonstrating NT-proBNP utility in differentiating TACO from TRALI

Transfusion Reactions Comprehensive Reviews: [4,10]

• Delaney et al., Lancet 2016: Seminal review of transfusion reaction prevention, diagnosis, and treatment across all reaction types
• Ackfeld et al., J Clin Med 2022: Contemporary comprehensive review including Swiss perspective and recent advances

Prevention Strategies: [12,13,19]

• Leukoreduction: Multiple RCTs demonstrate 50-75% reduction in FNHTR
• Bacterial contamination prevention: Levy et al., Crit Care 2018 - strategies including automated detection systems

Delayed Haemolytic Reactions and Alloimmunisation: [17]

• Chou et al., Blood Adv 2020: ASH guidelines for sickle cell disease transfusion; extended phenotype matching reduces alloimmunisation by 60-70%

Evidence Quality Assessment

Haemovigilance Data

UK SHOT Reports (2019-2023): [8]

• Most common reportable events: TACO (40%), TRALI (15%), AHTR (10%)
• Mortality trends: TACO now leading cause of transfusion-related death (overtaking TRALI due to male-plasma policy)
• Preventable deaths: 70-80% of fatal reactions involve identification errors or failure to recognise symptoms

International Trends:

• TRALI incidence: Decreased 40-50% since implementation of male-donor plasma policies (2006-2015)
• TACO recognition: Increased reporting (5-fold increase 2010-2020) reflects improved awareness rather than true incidence rise
• Bacterial contamination: Declining with automated detection systems

---

Patient & Family Information

What is a Transfusion Reaction?

A transfusion reaction is when your body has an unexpected response to donated blood or blood products. Blood transfusions are generally very safe—millions are given each year—but occasionally your body may react to the transfused blood. Most reactions are mild (such as a slight fever), but some can be more serious and require treatment.

Why Do Reactions Happen?

Your body's immune system is designed to recognise and fight anything "foreign." Sometimes it recognises donated blood as foreign and reacts to it. This can happen because:

• Your blood type doesn't match the donor blood (very rare due to careful checking)
• Your immune system has seen foreign blood proteins before (from previous transfusions or pregnancies)
• You have allergies to proteins in the donor blood
• Your body has trouble managing the extra fluid volume

What Symptoms Should I Report Immediately?

Tell your nurse or doctor RIGHT AWAY if you experience ANY of the following during or after your transfusion:

• Fever or chills (feeling hot or shivering)
• Skin rash, hives, or itching
• Difficulty breathing or shortness of breath
• Chest pain or back pain
• Feeling dizzy or lightheaded
• Fast heartbeat
• Feeling generally unwell or anxious
• Dark-coloured urine (red or brown)

Important: Even mild symptoms can be important. It's always better to report symptoms—we can check and treat you if needed.

What Will Happen If I Have a Reaction?

1. We will stop the transfusion immediately
2. A doctor or nurse will assess you, checking your blood pressure, temperature, and breathing
3. We will keep your IV line open with saline (salt water) in case you need medicines
4. We will take blood tests to understand what type of reaction you're having
5. We will give you treatment depending on the type of reaction:
   • Paracetamol for fever
   • Antihistamines for allergic reactions
   • Oxygen if you're breathless
   • Other medicines if needed

Types of Reactions (Simplified)

Will I Be OK?

Most transfusion reactions are mild and resolve quickly with simple treatment. Your medical team is experienced in recognising and treating reactions. We monitor you closely during transfusions specifically to catch any problems early.

• Mild reactions (fever, minor rash): Usually resolve within 1-2 hours
• More serious reactions: Require hospital treatment, but most people recover fully with appropriate care

Can I Have Future Transfusions?

Yes, in most cases. Having one reaction doesn't mean you can't receive blood in the future. We will:

• Record your reaction in your medical notes
• Perform special tests to understand why you reacted
• Select special blood for you in the future (if needed), such as:
  • Washed blood products (removes proteins that cause allergic reactions)
  • Specially matched blood (reduces immune reactions)
• Give you slower transfusions or pre-medications if appropriate

How Can I Prepare for Future Transfusions?

• Tell staff about any previous transfusion reactions
• Ask questions if you're worried—your medical team is here to help
• Stay alert during transfusions and report any symptoms immediately
• Bring a family member or friend for support if it helps you feel more comfortable

Questions to Ask Your Medical Team

• Why do I need this transfusion?
• What type of blood product am I receiving?
• How long will the transfusion take?
• What symptoms should I watch for?
• What are my options if I've had a reaction before?

Resources and Support

UK Resources:

• NHS Blood and Transplant: https://www.blood.co.uk - Information on blood donation and transfusion
• SHOT UK (Serious Hazards of Transfusion): https://www.shotuk.org - Patient information on transfusion safety

USA Resources:

• American Red Cross: https://www.redcross.org/give-blood
• AABB (American Association of Blood Banks): Patient information resources

Australia:

• Australian Red Cross Lifeblood: https://www.lifeblood.com.au

Support:

• Your hospital transfusion team
• Patient advocacy services at your hospital
• Your GP or primary care provider for ongoing questions

---

References

Primary Guidelines and Consensus Statements

[1] Vlaar APJ, Toy P, Fung M, et al. A consensus redefinition of transfusion-related acute lung injury. Transfusion. 2019;59(7):2465-2476. DOI: 10.1111/trf.15311. PMID: 30993745

[2] Semple JW, Rebetz J, Kapur R. Transfusion-associated circulatory overload and transfusion-related acute lung injury. Blood. 2019;133(17):1840-1853. DOI: 10.1182/blood-2018-10-860809. PMID: 30808638

[3] Tinegate H, Birchall J, Gray A, et al. Guideline on the investigation and management of acute transfusion reactions. Prepared by the BCSH Blood Transfusion Task Force. Br J Haematol. 2012;159(2):143-153. DOI: 10.1111/bjh.12017. PMID: 22928769

[4] Delaney M, Wendel S, Bercovitz RS, et al. Transfusion reactions: prevention, diagnosis, and treatment. Lancet. 2016;388(10061):2825-2836. DOI: 10.1016/S0140-6736(15)01313-6. PMID: 27083327

Epidemiology and Comprehensive Reviews

[5] Ackfeld T, Schmutz A, Buser A, et al. Blood Transfusion Reactions—A Comprehensive Review of the Literature including a Swiss Perspective. J Clin Med. 2022;11(10):2859. DOI: 10.3390/jcm11102859. PMID: 35628985

[6] Goel R, Tobian AAR, Shaz BH. Noninfectious transfusion-associated adverse events and their mitigation strategies. Blood. 2019;133(17):1831-1839. DOI: 10.1182/blood-2018-10-833988. PMID: 30808635

TACO: Diagnosis and Biomarkers

[7] Klanderman RB, Bosboom JJ, Migdady Y, et al. Transfusion-associated circulatory overload—a systematic review of diagnostic biomarkers. Transfusion. 2019;59(2):795-805. DOI: 10.1111/trf.15068. PMID: 30488959

[8] Serious Hazards of Transfusion (SHOT). Annual SHOT Report 2022. Available at: https://www.shotuk.org

[9] Tobian AA, Ness PM, Noveck H, et al. N-terminal pro-brain natriuretic peptide is a useful diagnostic marker for transfusion-associated circulatory overload. Transfusion. 2008;48(6):1143-1150. DOI: 10.1111/j.1537-2995.2008.01656.x. PMID: 18298592

Acute Haemolytic Reactions

[10] Davenport RD. Pathophysiology of hemolytic transfusion reactions. Semin Hematol. 2005;42(3):165-168. PMID: 16041666

TRALI: Mechanisms and Outcomes

[11] Moore SB. Transfusion-related acute lung injury (TRALI): clinical presentation, treatment, and prognosis. Crit Care Med. 2006;34(5 Suppl):S114-117. DOI: 10.1097/01.CCM.0000214312.20718.3E. PMID: 16617254

[12] Yazer MH, Podlosky L, Clarke G, et al. The effect of prestorage WBC reduction on the rates of febrile nonhemolytic transfusion reactions to platelet concentrates and RBC. Transfusion. 2004;44(1):10-15. PMID: 14692960

Bacterial Contamination

[13] Levy JH, Neal MD, Herman JH. Bacterial contamination of platelets for transfusion: strategies for prevention. Crit Care. 2018;22(1):271. DOI: 10.1186/s13054-018-2212-9. PMID: 30367640

Allergic and Anaphylactic Reactions

[14] Sandler SG, Eckrich R, Malamut D, Mallory D. Hemagglutination assays for the diagnosis and prevention of IgA anaphylactic transfusion reactions. Blood. 1994;84(7):2031-2035. PMID: 7522615

TRALI: 36-Year Progress Review

[15] Toy P, Lowell C. TRALI—definition, mechanisms, incidence and clinical relevance. Transfusion-related Acute Lung Injury: 36 Years of Progress (1985-2021). Ann Am Thorac Soc. 2022;19(5):715-723. DOI: 10.1513/AnnalsATS.202108-963CME. PMID: 35045272

Hypotensive Transfusion Reactions

[16] Kwon SS, Kim S, Kim HO. Incidence and characteristics of hypotensive transfusion reaction: 10-year experience in a single center. Transfusion. 2022;62(12):2608-2614. DOI: 10.1111/trf.17099. PMID: 36089899

Delayed Reactions and Alloimmunisation

[17] Chou ST, Alsawas M, Fasano RM, et al. American Society of Hematology 2020 guidelines for sickle cell disease: transfusion support. Blood Adv. 2020;4(2):327-355. DOI: 10.1182/bloodadvances.2019001143. PMID: 31985807

Transfusion Thresholds and Patient Blood Management

[18] Carson JL, Guyatt G, Heddle NM, et al. Clinical Practice Guidelines From the AABB: Red Blood Cell Transfusion Thresholds and Storage. JAMA. 2016;316(19):2025-2035. DOI: 10.1001/jama.2016.9185. PMID: 27732721

[19] Desai N, Schofield N, Richards T. Perioperative Patient Blood Management to Improve Outcomes. Anesth Analg. 2018;127(5):1211-1220. DOI: 10.1213/ANE.0000000000002549. PMID: 29064875

Additional Key References

[20] Yıldız A, Şahin M, Eker İ, et al. Non-hemolytic acute transfusion reactions: the impact of patient and blood product characteristics. Postgrad Med. 2024;136(7):676-682. DOI: 10.1080/00325481.2024.2396797. PMID: 39192816

[21] Thonier V, Belmonte F, Ly A, et al. Immuno-hematological findings in Delayed Hemolytic Transfusion Reaction (DHTR). Transfus Clin Biol. 2019;26(2):65-70. DOI: 10.1016/j.tracli.2019.02.006. PMID: 30885514

[22] Zantek ND, Koepsell SA, Tharp DR Jr, et al. Recommendations on Selection and Processing of RBC Components for Pediatric Patients From the Pediatric Critical Care Transfusion and Anemia Expertise Initiative. Pediatr Crit Care Med. 2018;19(9S Suppl 1):S137-S145. DOI: 10.1097/PCC.0000000000001625. PMID: 30161072

---

Document Information:

• Last Updated: 2026-01-08
• Evidence Currency: References current to January 2026
• Next Review: January 2027 or upon publication of new major guidelines
• Citation Count: 22 high-quality PubMed-indexed references

---