By the end of this note you will be able to describe the clinical approach to blood transfusion and its reactions, recognise risk factors common in Kenya, interpret key investigations and outline immediate and definitive management. Always verify doses and local protocols against the Kenya MoH guideline and your hospital formulary.
Definition
Blood transfusion is the intravenous administration of whole blood or blood components (red cells, plasma, platelets, cryoprecipitate) to a recipient for therapeutic or prophylactic purposes. A transfusion reaction is any adverse symptom or sign occurring during or within 24 h of the transfusion that is temporally related to the infused product and not explained by the underlying disease.
Anatomy and physiology you need
| Structure | Relevance to transfusion |
|---|---|
| Vascular endothelium | Barrier to plasma proteins; site of immune complex deposition |
| Red blood cell membrane antigens (ABO, Rh, Kell, Duffy…) | Basis of allo‑immunisation and hemolysis |
| Plasma proteins (IgG, IgM, complement) | Mediate immune‑mediated reactions |
| Coagulation cascade | Determines need for plasma/cryoprecipitate |
| Platelet receptors (GPIb, GPIIb/IIIa) | Target of allo‑antibodies causing platelet destruction |
| Spleen and reticulo‑endothelial system | Clears opsonised cells; site of sequestration in hemolysis |
Understanding these structures helps explain why mismatched antigens, antibodies, or cytokines provoke specific clinical pictures.
Causes and risk factors
- Immunologic mismatches – ABO incompatibility, RhD allo‑immunisation, minor antigen antibodies (Kell, Duffy, etc.).
- Previous sensitisation – prior transfusion, pregnancy, or transplantation.
- Infectious agents prevalent in Kenya – HIV, hepatitis B/C, malaria parasites, Treponema pallidum, Mycobacterium tuberculosis (rarely transmitted but relevant for donor screening).
- Underlying haematological disorders – sickle cell disease (auto‑antibodies, functional asplenia), thalassaemia, hereditary spherocytosis.
- Auto‑immune diseases – systemic lupus erythematosus, rheumatoid arthritis (cold agglutinins).
- Medications – recent monoclonal antibodies (e.g., rituximab) can mask antibody detection; antibiotics (penicillins) may cause drug‑dependent antibodies.
- Storage lesions – older red cells release cytokines, potassium, free hemoglobin → febrile non‑hemolytic reactions, hyperkalemia.
- Transfusion of massive volumes – risk of circulatory overload, especially in children, pregnant women, renal failure.
- Improper bedside practices – rapid infusion, failure to verify patient identity, using contaminated equipment.
Pathophysiology
Immunologic hemolysis → donor RBC antigens recognized by recipient antibodies → complement activation → intravascular lysis → free Hb → renal tubular injury & jaundice.
Febrile non‑hemolytic reaction → donor leukocyte cytokines + recipient anti‑leukocyte antibodies → cytokine release → fever, chills.
Allergic reaction → plasma proteins (IgA, donor plasma allergens) → recipient IgE → histamine release → urticaria, pruritus, bronchospasm.
Transfusion‑related acute lung injury (TRALI) → donor anti‑HLA/HNA antibodies + recipient neutrophil activation → pulmonary capillary leak → non‑cardiogenic pulmonary edema.
Transfusion‑associated circulatory overload (TACO) → rapid or large‑volume infusion → increased hydrostatic pressure → pulmonary congestion, hypertension.
Septic reaction → contaminated blood product → bacterial proliferation → endotoxin release → shock, fever, DIC.
Delayed hemolytic reaction → anamnestic antibody response (usually IgG) → RBC destruction 5‑10 days post‑transfusion → falling Hb, jaundice, mild fever.
Graft‑versus‑host disease (GVHD) → viable donor lymphocytes engraft → host tissue attack → fever, rash, liver dysfunction, pancytopenia (rare, higher risk in immunocompromised).
Iron overload (chronic) → repeated red cell transfusions → excess iron deposition → hepatic, cardiac, endocrine damage.
Clinical features
| Domain | Key questions / findings | Why it occurs |
|---|---|---|
| Timing | When did the transfusion start? <br> When did symptoms appear? | Acute reactions usually begin ≤ 4 h (most within minutes). Delayed reactions appear days to weeks later. |
| Fever | Did temperature rise during or after the transfusion? <br> Any chills or rigors? | Cytokine release (febrile non‑hemolytic), bacterial contamination, or hemolysis provoke pyrogenic response. |
| Pain | Any pain at the infusion site, back, chest, abdomen, joints or muscles? | - Infusion‑related: venous irritation, extravasation. <br> - Hemolysis: retro‑orbital, flank or back pain from renal vasoconstriction. |
| Skin | Rash, urticaria, flushing, itching, or mottled discoloration? | IgE‑mediated anaphylaxis, complement activation (TRALI), or immune complex deposition (serum sickness). |
| Respiratory | Shortness of breath, cough, wheeze, or chest tightness? | Pulmonary capillary leak (TRALI), bronchospasm (anaphylaxis), fluid overload. |
| Cardiovascular | Palpitations, hypotension, tachycardia, or hypertension? | Anaphylaxis (vasodilation, capillary leak), hemolysis (hypotension from volume loss), volume overload. |
| Renal | Decreased urine output, hematuria, flank pain? | Acute tubular necrosis from hemoglobinuria (intravascular hemolysis) or pigment nephropathy. |
| Neurological | Dizziness, headache, visual changes, seizures? | Cerebral hypoperfusion (anaphylaxis), micro‑emboli (TRALI), or severe anemia from hemolysis. |
| Bleeding / Hemolysis | Dark urine, jaundice, pallor, or increased bleeding? | Massive hemolysis releases bilirubin, hemoglobin; consumptive coagulopathy may develop. |
| Past transfusion history | Previous reactions, allo‑immunisation, antibodies? | Prior sensitisation raises risk of delayed hemolytic or anaphylactic reactions. |
| Co‑morbidities | HIV, TB, malaria, sickle cell disease, rheumatic heart disease, pregnancy? | Underlying disease may predispose to specific reactions (e.g., allo‑antibodies in sickle cell, hyper‑immune state in pregnancy). |
| Medications | Recent antibiotics, immunosuppressants, antihistamines? | Certain drugs (e.g., ceftriaxone) can cause immune complex reactions; antihistamines may mask early signs. |
Examination
- Vital signs – fever, tachycardia, hypotension, tachypnoea, oxygen desaturation.
- Skin – urticarial wheals, petechiae, cyanosis, flushing.
- Respiratory – crackles, wheeze, use of accessory muscles; auscultation for pulmonary edema.
- Cardiovascular – volume status, peripheral pulses, jugular venous pressure.
- Abdomen – flank tenderness (renal involvement).
- Neurological – level of consciousness, focal deficits.
Each finding reflects the underlying pathophysiology of the reaction and guides urgency of intervention.
Differential diagnosis
| Condition | Points toward it | How it differs from other transfusion reactions |
|---|---|---|
| Acute hemolytic transfusion reaction (AHTR) | Fever, flank pain, dark urine, hypotension, rapid fall in Hb, positive direct Coombs | Immediate onset, evidence of intravascular hemolysis, complement‑mediated, not primarily respiratory. |
| Febrile non‑hemolytic transfusion reaction (FNHTR) | Fever ≥ 1 °C, chills, no hemolysis, normal urine, mild rigors | No hemoglobinuria, no drop in Hb, no respiratory distress. |
| Allergic/Anaphylactic reaction | Urticaria, itching, wheeze, hypotension, rapid onset, often in IgA‑deficient patients | Prominent cutaneous & respiratory signs, no hemolysis, responds to epinephrine. |
| Transfusion‑related acute lung injury (TRALI) | Acute dyspnoea, hypoxia, bilateral infiltrates, no fluid overload, within 6 h | Pulmonary infiltrates dominate, normal cardiac exam, no hemoglobinuria. |
| Transfusion‑associated circulatory overload (TACO) | Hypertension, JVP elevation, pulmonary edema, cardiomegaly, response to diuretics | Evidence of volume overload, cardiac signs, slower onset (within 6 h). |
| Bacterial contamination | High‑grade fever, rigors, hypotension, possible sepsis, positive blood cultures | Fever disproportionate to volume, may have shock, no hemolysis. |
| Delayed hemolytic transfusion reaction (DHTR) | Fever, jaundice, falling Hb 3‑14 days post‑transfusion, positive indirect Coombs | Delayed onset, extravascular hemolysis, less severe renal impact. |
Investigations
| Test | What it answers | Interpretation |
|---|---|---|
| Direct antiglobulin test (DAT/Coombs) | Presence of IgG or complement on patient’s RBCs | Positive → immune‑mediated hemolysis (AHTR, DHTR). |
| Serum free hemoglobin | Degree of intravascular hemolysis | Elevated → AHTR, severe hemolysis. |
| Haptoglobin | Binding capacity for free hemoglobin | Low → intravascular hemolysis. |
| LDH | Cell breakdown marker | Raised in hemolysis. |
| Bilirubin (total & indirect) | Hemoglobin catabolism | ↑ indirect → hemolysis. |
| Urine dipstick (blood, hemoglobin) | Hemoglobinuria vs. hematuria | Positive for blood without RBCs → hemoglobinuria. |
| CBC with reticulocyte count | Anemia severity & marrow response | Falling Hb with retic rise → hemolysis; retic low → dilutional. |
| Chest X‑ray | Pulmonary infiltrates, cardiomegaly | Bilateral infiltrates w/ normal heart → TRALI; cardiomegaly → TACO. |
| Blood cultures | Bacterial contamination | Positive → septic transfusion reaction. |
| Serum tryptase (if available) | Mast cell activation | Elevated → anaphylaxis. |
| ABO/Rh repeat typing & antibody screen | Verify compatibility, detect new allo‑antibodies | Discrepancy → clerical error; new antibodies → delayed hemolysis. |
Diagnosis and severity
| Reaction type | Diagnostic criteria (core) | Severity grading* |
|---|---|---|
| Acute hemolytic transfusion reaction | Fever, flank pain, ↓Hb, ↑LDH, ↓haptoglobin, positive DAT, hemoglobinuria, timing ≤ 4 h | Mild – symptoms controlled with fluids; Moderate – hypotension, renal impairment; Severe – shock, disseminated intravascular coagulation, death. |
| Febrile non‑hemolytic | Fever ≥ 1 °C, chills, no hemolysis labs, ≤ 4 h | Mild – resolves with antipyretics; Moderate – persistent high fever > 2 h; Severe – fever > 40 °C, hemodynamic change. |
| Allergic/Anaphylactic | Urticaria ± wheeze, hypotension, rapid onset, possible positive tryptase | Mild – limited cutaneous; Moderate – respiratory involvement; Severe – hypotension, airway compromise. |
| TRALI | Acute hypoxia, PaO₂/FiO₂ < 300, bilateral infiltrates, no cardiac overload, ≤ 6 h | Mild – oxygen requirement < 2 L/min; Moderate – need > 2 L/min, ICU admission; Severe – mechanical ventilation, multi‑organ failure. |
| TACO | Signs of volume overload, BNP rise, cardiomegaly, ≤ 6 h | Mild – responds to diuretics; Moderate – persistent edema, O₂ > 4 L/min; Severe – respiratory failure, need for ventilation. |
| Bacterial contamination | Fever > 38 °C, rigors, hypotension, positive cultures, ≤ 6 h | Mild – fever only; Moderate – sepsis criteria; Severe – septic shock. |
| Delayed hemolytic transfusion reaction | Fever, jaundice, falling Hb 3‑14 days, positive indirect Coombs, no acute renal signs | Mild – asymptomatic fall in Hb; Moderate – symptomatic anemia, jaundice; Severe – renal impairment, severe anemia. |
*Severity is based on clinical impact, need for organ‑support, and response to initial measures.
Prompt recognition, classification, and escalation of care according to severity are essential for optimal outcomes in the Kenyan clinical setting.
Management
Immediate stabilisation
- Stop the transfusion at the first sign of a reaction (fever, rash, dyspnoea, hypotension, chest pain, dark urine).
- Maintain airway, breathing, circulation – give 100 % oxygen, place the patient in a semi‑recumbent position, and secure IV access with a new line if the current line is compromised.
- Notify the blood bank and complete the transfusion reaction form; retain the remaining blood product and tubing for investigation.
Definitive treatment – varies with reaction type
| Reaction type | First‑line therapy | Rationale |
|---|---|---|
| Acute hemolytic (ABO‑incompatible) | Aggressive IV crystalloids, consider albumin, monitor urine output, give diuretics if oliguria | Prevent renal tubular injury from free haemoglobin; maintain perfusion |
| Febrile non‑haemolytic | Antipyretics (paracetamol) | Symptomatic relief; no immune suppression needed |
| Allergic (urticarial) | Antihistamine (H1 blocker) ± short course corticosteroid | Blocks histamine release, reduces rash/pruritus |
| Anaphylaxis | IM epinephrine, IV fluids, high‑flow O₂, antihistamine, corticosteroid | Rapid reversal of airway edema and hypotension |
| Transfusion‑related acute lung injury (TRALI) | Supportive ventilation, diuretics only if fluid overload, avoid diuretics if hypovolaemic | Lung injury is immune‑mediated; fluid balance is key |
| Transfusion‑associated circulatory overload (TACO) | IV diuretics, oxygen, consider CPAP/NIV | Relieve pulmonary congestion |
| Delayed hemolytic | Corticosteroid (if severe), monitor Hb, give compatible washed RBCs if repeat transfusion needed | Immune‑mediated destruction; steroids blunt antibody response |
Monitoring
- Vital signs every 5 min for the first 30 min, then hourly for 2 h.
- Urine colour and output; send urine for haemoglobin and microscopy.
- Repeat CBC, LDH, bilirubin, haptoglobin at 6 h and 24 h for haemolysis.
- Chest X‑ray if respiratory symptoms develop.
Follow‑up
- Review reaction work‑up (direct antiglobulin test, culture of product, clerical check).
- Counsel patient on future transfusion compatibility; issue an alert on the hospital record.
- Arrange outpatient haematology review for patients with allo‑immunisation or severe reactions.
Contra‑indications & safety
- Do not re‑infuse the implicated product.
- Avoid pre‑medication (antihistamines, acetaminophen) as a routine prophylaxis; it masks early signs.
- Do not give diuretics in TRALI or anaphylaxis unless fluid overload is evident.
- Ensure correct patient identification (two‑person check) before every unit.
Complications and prognosis
| Complication | Typical outcome | Key preventive measure |
|---|---|---|
| Acute hemolytic reaction | Can lead to acute renal failure, DIC, death if untreated | Strict ABO/Rh matching, double‑check patient ID |
| TRALI | Mortality 5–10 %; most recover with supportive care | Use plasma from male donors or screened female donors |
| TACO | Mortality up to 15 % in frail patients | Assess volume status, limit rate, use diuretics prophylactically in high‑risk |
| Febrile non‑haemolytic | Benign, resolves in hours | Leukoreduction of blood components |
| Allergic / anaphylactic | Usually self‑limited; anaphylaxis can be fatal | Use washed RBCs for IgA‑deficient patients |
| Delayed hemolytic | Mild anaemia, may require repeat compatible unit | Extended phenotyping, consider genotyping in multiply transfused |
| Transfusion‑transmitted infections (HIV, HBV, malaria, TB) | Chronic disease; malaria can be severe in non‑immune | Rigorous donor screening, pathogen‑reduction where available |
Overall prognosis is excellent when reactions are recognised early and managed promptly. Severe immune‑mediated reactions carry higher morbidity and require close follow‑up.
High‑yield exam points
- Look‑alike conditions:
- Fever + rigors → differentiate bacterial sepsis from febrile non‑haemolytic reaction (culture, timing).
- Dyspnoea + hypoxia → distinguish TRALI (non‑cardiogenic, normal PCWP) from TACO (cardiogenic, elevated JVP).
- Commonest wrong first step: Continuing the transfusion after the first symptom; the correct action is to stop immediately.
- Examiner may ask:
- “What three checks do you perform before starting a unit?” (patient ID, blood product ID, bedside compatibility).
- “How would you differentiate an acute hemolytic reaction from a febrile non‑haemolytic reaction?” (presence of hemoglobinuria, rapid fall in Hb, positive direct Coombs).
- “Why is pre‑medication not recommended routinely?” (it can mask early signs, does not prevent reactions).
Clinical case
Case: A 28‑year‑old male with sickle cell disease presents with severe anaemia (Hb 5 g/dL) after a vaso‑occlusive crisis. He receives two units of cross‑matched packed RBCs. Ten minutes into the second unit he develops chills, fever 38.5 °C, diffuse urticaria, and his BP falls to 90/55 mmHg.
Questions
- What is the most likely reaction?
Answer: Acute allergic (urticarial) reaction progressing to anaphylaxis.
- What is the immediate management?
Answer: Stop the transfusion, call for help, give IM epinephrine, place on high‑flow O₂, start IV crystalloids, and administer an H1 antihistamine.
- What investigation will confirm the diagnosis and guide future transfusions?
Answer: Serum tryptase (elevated in anaphylaxis) and IgA level; if IgA deficiency is confirmed, future units should be washed or IgA‑deficient donor blood.
Practice questions
Question 1
A 65‑year‑old woman with chronic heart failure receives a unit of PRBCs. Fifteen minutes later she becomes tachypnoeic, SpO₂ 86 % on room air, and has bibasal crackles. BP is 130/80 mmHg. What is the most appropriate next step?
A. Give IV furosemide
B. Stop the transfusion and give high‑flow O₂
C. Increase the transfusion rate
D. Administer IV epinephrine
Answer: B. Stop the transfusion and give high‑flow O₂
Explanation: The presentation is classic for TRALI (non‑cardiogenic pulmonary oedema); the first action is to halt the transfusion and provide oxygen. Diuretics are reserved for TACO.
Question 2
A 40‑year‑old man develops fever, rigors, and dark urine 2 h after a transfusion. Labs show a fall in Hb from 9 to 6 g/dL, ↑LDH, ↓haptoglobin, and a positive direct antiglobulin test. Which statement is true?
A. This is a delayed hemolytic reaction
B. The reaction is most likely due to bacterial contamination
C. Immediate management includes aggressive IV fluids and monitoring renal function
D. Pre‑treating with antipyretics would have prevented it
Answer: C. Immediate management includes aggressive IV fluids and monitoring renal function
Explanation: The findings indicate an acute hemolytic transfusion reaction; fluid resuscitation protects the kidneys. It is not delayed, nor bacterial, and antipyretics do not prevent hemolysis.
Question 3
A 30‑year‑old pregnant woman receives a single unit of washed RBCs for severe anaemia. Two hours later she develops a temperature of 38 °C, chills, and a diffuse maculopapular rash. Which investigation is most useful?
A. Blood culture of the remaining unit
B. Repeat ABO typing
C. Serum IgA level
D. Direct Coombs test
Answer: A. Blood culture of the remaining unit
Explanation: Fever with rash after transfusion raises suspicion of bacterial contamination; culturing the product is essential. The other tests are less relevant to this presentation.
Question 4
Which of the following is a contraindication to giving a second unit of blood to a patient who has just experienced a febrile non‑haemolytic reaction?
A. Presence of mild urticaria
B. Persistent temperature >38 °C after antipyretic
C. History of IgA deficiency
D. Low pre‑transfusion Hb
Answer: B. Persistent temperature >38 °C after antipyretic
Explanation: Ongoing fever suggests the reaction is not resolved; the transfusion should be withheld until the cause is clarified.
Question 5
A 22‑year‑old male with malaria‑induced severe anaemia receives a transfusion. Six days later he presents with jaundice, a drop in Hb, and a positive indirect Coombs test. What is the most likely diagnosis?
A. Acute hemolytic reaction
B. Delayed hemolytic transfusion reaction
C. Autoimmune haemolytic anaemia unrelated to transfusion
D. G6PD deficiency‑related haemolysis
Answer: B. Delayed hemolytic transfusion reaction
Explanation: The delayed timing (≥5 days), falling Hb, and positive indirect Coombs are characteristic of a delayed hemolytic reaction.
Drafted with AI assistance from standard references and reviewed for structure. Check details against your lecture notes and the Kenya MoH guideline.