Complication of blood transfusion

Overview & Classification

Blood transfusion is lifesaving but carries real risks. Complications are classified along two axes: timing (acute, < 24 hours vs delayed, > 24 hours) and mechanism (immune-mediated vs non-immune). Overlaying these two axes produces the core 2×2 matrix that nearly every exam question is built on.

The timing of symptom onset after a transfusion is the single most useful diagnostic clue — anaphylaxis and acute hemolysis strike within seconds to minutes, febrile/respiratory reactions within 1–6 hours, and hemolytic/immunologic delayed reactions appear 2–10 days later.

The remainder of this lesson works through this grid: acute immune reactions, other acute reactions, then delayed complications, and finally a universal emergency protocol. The Immunologic Blood Transfusion Reactions reference organizes each immune reaction by onset, cause, and key features if you want the one-page summary.

Acute Immune Reactions (&lt; 24 h)

Four immune-mediated reactions appear within 24 hours of transfusion. For each, anchor on mechanism, onset, key features, and the specific next step.

1. Acute Hemolytic Transfusion Reaction (AHTR)

• Mechanism: recipient preformed IgM against ABO antigens on donor RBCs → complement activation → intravascular hemolysis (type II hypersensitivity). Almost always a clerical error (wrong unit / wrong patient).
• Onset: within minutes of starting the transfusion.
• Key features: fever, chills, flank/back pain, hypotension, tachycardia, hemoglobinuria (dark urine), DIC, acute kidney injury. In an anesthetized patient, diffuse surgical-wound oozing + hypotension may be the only clue.
• Labs: ↑ LDH, ↑ indirect bilirubin, ↓ haptoglobin, positive direct Coombs (DAT), hemoglobinuria.
• Management: STOP transfusion; aggressive IV normal saline to keep urine output > 100 mL/hr; treat shock/DIC; return bag + fresh patient sample to the blood bank.

Important – فكرة سؤال

Fever + flank/back pain + dark (hemoglobinuric) urine + hypotension within minutes of starting a transfusion = Acute Hemolytic Transfusion Reaction (ABO mismatch / clerical error). First step: STOP the transfusion, keep the line open with IV normal saline to protect the kidneys, and return the bag + a fresh patient sample to the blood bank. حمى + ألم أسفل الظهر + بول داكن + هبوط ضغط أثناء النقل ← أوقف النقل فوراً.

تذكر

2. Febrile Non-Hemolytic Transfusion Reaction (FNHTR)

• The most common transfusion reaction — a diagnosis of exclusion.
• Mechanism: cytokines (IL-1, IL-6, TNF) accumulated from donor WBCs during storage, or recipient anti-HLA antibodies reacting with donor leukocytes.
• Onset: 1–6 hours after the transfusion starts.
• Key features: fever (≥ 1 °C rise), chills, malaise. No hemolysis, no hypotension, no respiratory distress.
• Management: stop transfusion (must rule out AHTR), give antipyretics (acetaminophen); self-limiting. Prevent future episodes with leukoreduced products.

3. Allergic and Anaphylactic Reactions

• Mild allergic (urticarial): type I hypersensitivity to donor plasma proteins → urticaria, pruritus, flushing within minutes; no fever, no hypotension. Pause transfusion, give antihistamines (diphenhydramine); may resume slowly if symptoms resolve — the only reaction in which restarting the same unit is acceptable.
• Anaphylactic: classically an IgA-deficient recipient with anti-IgA antibodies reacting against donor plasma IgA. Onset seconds–minutes: hypotension, shock, bronchospasm/wheeze, stridor, angioedema, ± vomiting. STOP transfusion → IM epinephrine, IV fluids, airway support, antihistamines/steroids. Prevent with washed RBCs or IgA-deficient donor units.

Note – ملاحظة
Selective IgA deficiency is the most common primary immunodeficiency. Most patients are asymptomatic but carry a lifelong risk of anaphylaxis from any blood product containing IgA. Prevent with washed RBCs or products from IgA-deficient donors.	ملاحظة

4. Transfusion-Related Acute Lung Injury (TRALI)

• Mechanism: donor anti-HLA / anti-neutrophil antibodies activate recipient neutrophils in the pulmonary microvasculature → capillary leak → non-cardiogenic pulmonary edema (ARDS-like).
• Onset: within 6 hours.
• Key features: acute dyspnea + hypoxia, bilateral pulmonary infiltrates, often hypotension and fever; no signs of fluid overload (normal JVP, normal BNP).
• Management: STOP transfusion; supportive oxygen / mechanical ventilation. Most recover in 24–72 h; mortality up to ~50% in previously critically ill patients. Full TRALI vs TACO comparison follows in the next section.

Important – فكرة سؤال
TRALI is the leading cause of transfusion-related death. Dyspnea + hypoxia + bilateral infiltrates within 6 hours, often with hypotension and fever — it looks like ARDS triggered by transfusion. Treatment is supportive (oxygen, mechanical ventilation) — do NOT give diuretics (this is not volume overload). Risk factors include smoking, alcohol use, and critical illness.	تذكر

When fever, rash, or respiratory distress appears mid-transfusion, the differential diagnosis of acute transfusion reactions by symptom maps each cardinal symptom to its likely reaction.

Other Acute Reactions (&lt; 24 h)

The remaining acute reactions are non-immune: circulatory overload, bacterial sepsis, and the metabolic derangements of massive transfusion.

1. Transfusion-Associated Circulatory Overload (TACO)

• Mechanism: too much volume too fast → ↑ hydrostatic pressure → cardiogenic (hydrostatic) pulmonary edema.
• Onset: during or within 6 hours of transfusion.
• Key features: dyspnea, hypertension, raised JVP, S3 gallop, peripheral edema; ↑ BNP and cardiomegaly on CXR — a classic CHF picture. Risk: elderly, CHF, renal failure, infants.
• Management: slow or stop transfusion, sit the patient upright, give oxygen and IV furosemide; transfuse slowly and in divided units in future.

Distinguishing TRALI from TACO is a perennial exam question — both cause dyspnea and bilateral infiltrates within 6 hours, but the hemodynamics and management are opposite.

Important – فخ امتحاني

Both TRALI and TACO cause dyspnea + bilateral infiltrates within 6 hours — blood pressure is the key separator. TRALI → hypotension (capillary leak, normal heart, normal BNP) TACO → hypertension + raised JVP, S3, ↑ BNP (volume overload) فخ امتحاني: كلاهما يسبب ضيق تنفس، لكن الضغط هو الفارق الرئيسي. TRALI يسبب هبوط ضغط (Hypotension) بينما TACO يسبب ارتفاع ضغط (Hypertension). ابحث عن علامات فشل القلب في TACO.

تذكر

2. Septic (Bacterial Contamination) Reaction

• Mechanism: bacterial contamination of the product → endotoxin release in the recipient. Most often with platelets (stored at room temperature, ~22 °C). Organisms: Yersinia enterocolitica (cold-growing, in RBCs), Staphylococcus and gram-negatives (platelets).
• Onset: minutes to hours.
• Key features: high fever, rigors, hypotension, shock — mimics AHTR but without hemoglobinuria or back pain.
• Management: STOP transfusion → broad-spectrum IV antibiotics, IV fluids/vasopressors; culture both the patient and the bag.

Sepsis, anaphylaxis, TRALI, and AHTR all present with hypotension; the transfusion reactions associated with hypotension comparison separates the four by onset and cause.

3. Metabolic Complications of Massive Transfusion

Massive transfusion (≈ 1 blood volume / ~10 units in 24 h) produces predictable metabolic derangements:

• Hypocalcemia: citrate anticoagulant in stored blood chelates calcium → perioral tingling, tetany, prolonged QT; treat with IV calcium gluconate.
• Hyperkalemia: stored RBCs leak potassium → arrhythmia risk (especially renal failure, neonates).
• Also hypothermia (cold products — use a warmer) and dilutional coagulopathy/thrombocytopenia.

Refer to acute hypocalcemia: causes, features, and IV calcium treatment for the citrate mechanism and the Chvostek/Trousseau signs to look for.

Delayed Complications (&gt; 24 h)

Delayed complications surface days to years after transfusion. Each has a signature vignette.

1. Delayed Hemolytic Transfusion Reaction (DHTR)

• Classic vignette: an unexplained drop in hemoglobin 2–10 days (often ~7 days) after a "successful" transfusion, with low-grade fever and mild jaundice.
• Mechanism: anamnestic response — the recipient was previously sensitized (prior transfusion or pregnancy) to a minor RBC antigen (most often Kidd/Jk; also Rh, Duffy, Kell). The antibody titer was too low to detect on crossmatch, then rises after re-exposure → IgG-mediated extravascular hemolysis (spleen) → no hemoglobinuria.
• Labs: positive direct Coombs, ↑ indirect bilirubin, ↓ haptoglobin, ↓ Hb.
• Management: usually supportive; identify the offending antibody so future units are antigen-negative.

2. Transfusion-Associated GVHD (TA-GVHD)

• Mechanism: viable donor T lymphocytes engraft and attack the recipient's tissues.
• At risk: severely immunocompromised patients (BMT recipients, hematologic malignancy, congenital immunodeficiency, fetus) and transfusion from a first-degree relative (shared HLA haplotype lets donor T cells evade recognition).
• Onset: 4–30 days post-transfusion.
• Key features: fever, skin rash, diarrhea, hepatitis, pancytopenia — the recipient marrow is attacked (unlike BMT-GVHD, where marrow is spared). Mortality > 90%.
• Prevention: irradiate blood products to inactivate donor lymphocytes.

Note – ملاحظة سريرية
ملاحظة سريرية: تشعيع الدم (Irradiation) ضروري للمرضى ذوي المناعة المنخفضة وللتبرع من الأقارب من الدرجة الأولى لمنع TA-GVHD المميت.	ملاحظة

3. Iron Overload (Secondary Hemochromatosis)

• Classic vignette: a chronically transfused patient — β-thalassemia major, sickle cell disease, MDS.
• Each unit of RBCs contains ~250 mg iron and there is no physiologic excretory route, so iron deposits in heart (cardiomyopathy), liver (cirrhosis), pancreas (diabetes), skin (bronze), and gonads.
• Treatment: iron chelators — deferoxamine, deferasirox, deferiprone.

4. Alloimmunization & Transfusion-Transmitted Infections

Alloimmunization: repeated transfusion drives antibodies against donor RBC, HLA, or platelet antigens → future crossmatch difficulty, platelet refractoriness, and DHTR.

Infections are rare in modern screened banks but remain high-yield. Per-unit risk in developed countries (approximate): HBV ~1:1,000,000, HCV ~1:2,000,000, HIV ~1:2,000,000. CMV is the key pathogen for immunocompromised patients and neonates → use CMV-negative or leukoreduced units.

Emergency Management &amp; Prevention

Regardless of the suspected reaction, the first response is identical — recognize, stop, support, and investigate before you treat by type.

1. Step 1 — STOP the transfusion immediately at the first sign of any reaction.
2. Step 2 — Maintain IV access with normal saline through a new line — keeps the vein open and supports blood pressure and renal perfusion.
3. Step 3 — Reassess & verify: check vital signs; re-check the patient's identity against the unit label (clerical error is the #1 cause of AHTR).
4. Step 4 — Send to the blood bank: the blood bag, the IV tubing, and a fresh patient blood + urine sample for repeat crossmatch, direct Coombs, and culture.
5. Step 5 — Treat by reaction type: IM epinephrine for anaphylaxis; antipyretics for FNHTR; broad-spectrum antibiotics for sepsis; IV furosemide for TACO; supportive oxygen/ventilation for TRALI and AHTR (plus aggressive saline for AHTR).

Mnemonic – جملة تذكرية
First response to ANY suspected reaction — "STOP": S – Stop the transfusion immediately T – Tubing/IV kept open with normal saline (new line) O – Observe & recheck vitals; verify patient + unit ID P – Pack it back: send bag, tubing + fresh patient blood/urine to the blood bank	جملة تذكرية

Prevention — Modify the Product to Match the Patient

Targeted product modification is the primary tool for preventing recurrent or fatal reactions.

Prevention also starts with transfusing only when indicated — the RBC transfusion thresholds by hemoglobin level lay out the <7, 7–8, and 8–10 g/dL triggers that limit unnecessary exposure.