What is the most likely diagnosis for a postoperative patient who develops pain at the infusion site, fever, and chest tightness with a temperature of hyperthermia after starting a blood transfusion for postoperative bleeding?

Acute Hemolytic Transfusion Reaction (Answer: C)

The clinical triad of pain at the IV infusion site, fever (38°C), and chest tightness occurring within minutes of blood transfusion is most consistent with an acute hemolytic transfusion reaction, which represents a medical emergency requiring immediate cessation of transfusion. 1

Why This is Hemolytic Reaction, Not the Other Options

Distinguishing Features Present in This Case:

• Pain at the infusion site is the key distinguishing feature that points specifically to acute hemolytic reaction rather than other transfusion reactions 1
• Chest tightness indicates acute respiratory distress from systemic inflammation, not simple bronchospasm 1
• Rapid onset within minutes (not hours) of transfusion initiation strongly suggests hemolytic reaction or bacterial contamination 2
• The combination of all three symptoms together (IV site pain + fever + respiratory symptoms) within 10 minutes creates the characteristic triad for hemolytic reaction 1

Why NOT Febrile Non-Hemolytic Reaction (Option A):

• FNHTR presents with isolated fever and chills only, without the characteristic pain at the IV site 1
• FNHTR lacks the acute respiratory distress and hemodynamic instability seen in this patient 1
• FNHTR is much more common (incidence 1.1-2.15%) but is a diagnosis of exclusion after ruling out life-threatening causes 1

Why NOT Bacterial Contamination (Option B):

• While bacterial contamination can present with fever within 6 hours and is a leading cause of transfusion mortality, it typically presents with isolated fever initially 2, 3
• The immediate onset (within minutes) combined with IV site pain and chest tightness makes hemolytic reaction more likely 2
• Bacterial contamination is more common with platelet transfusions rather than packed red blood cells 2, 3

Why NOT Allergic Reaction (Option D):

• Allergic reactions typically manifest with urticaria, pruritus, and skin flushing rather than IV site pain 1
• Respiratory symptoms in allergic reactions are usually due to bronchospasm or laryngeal edema, not the acute dyspnea from systemic inflammation seen here 1
• The absence of skin manifestations and presence of IV site pain argues against allergic reaction 1

Critical Clinical Context

Epidemiology and Risk:

• The risk of acute hemolytic transfusion reactions is approximately 1:70,000 per unit transfused 1
• Mortality risk is estimated at 1:1,250,000 RBC units transfused 1
• Despite being rare, this is a medical emergency requiring immediate action 1

Common Pitfall to Avoid:

• Never dismiss fever during transfusion as "just FNHTR" without excluding life-threatening causes 2, 3
• General anesthesia and critical illness (including postoperative states) can mask early signs of serious reactions 2
• The postoperative setting does not make FNHTR more likely—all serious causes must be excluded first 2

Immediate Management Required

Stop the transfusion immediately and maintain IV access with normal saline 2, 1

• Monitor vital signs every 5-15 minutes, focusing on mean arterial pressure >65-70 mmHg 1
• Administer high-flow oxygen for respiratory distress 1
• Notify the transfusion laboratory/blood bank immediately 2
• Check patient identification and blood component compatibility labels for clerical errors 2
• Send the blood component bag with administration set back to the laboratory for analysis 2, 1
• Collect post-reaction blood samples for repeat crossmatch, direct antiglobulin test (Coombs test), complete blood count, and visual inspection of plasma for hemolysis 2, 1
• Perform urine analysis for hemoglobinuria 2, 1
• Initiate aggressive fluid resuscitation to maintain urine output >100 mL/hour to prevent renal failure 2