Mismatched Blood Transfusion: Hemolytic Reaction Mechanism and Emergency Management

ABO-incompatible transfusion triggers acute intravascular hemolysis – a medical emergency.

Pathophysiology

1. Recipient anti-A/B IgM binds donor RBC antigens.
2. Complement activation (C1–C9) → membrane attack complex (MAC) → intravascular hemolysis.
3. Free Hb, heme, iron, potassium, enzymes released.

Clinical Presentation

• Immediate (during/within hours): fever, chills, flank pain, dark urine, hypotension, DIC, renal failure, shock.
• Delayed (days): extravascular hemolysis, jaundice, falling Hb.

Emergency Management

1. STOP TRANSFUSION immediately.
2. IV fluids (NS) – maintain urine output >100 mL/h.
3. Furosemide (if not oliguric) → prevent tubular precipitation.
4. Monitor: Hb, haptoglobin, LDH, bilirubin, creatinine, electrolytes, coagulation, urine Hb.
5. Treat DIC: cryoprecipitate, platelets, FFP.
6. Dialysis if AKI.
7. Exchange transfusion rarely needed.

Prevention (Zero Tolerance)

• Positive patient ID (2 identifiers).
• Type and screen (valid 72h).
• Electronic barcode verification at bedside.
• Two-person check.
• Transfusion reaction workup protocol.