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

Acute Hemolytic Transfusion Reaction or Bacterial Contamination

The most likely diagnosis is either an acute hemolytic transfusion reaction (Option C) or bacterial blood contamination (Option B), and these two life-threatening conditions must be differentiated immediately—the combination of fever, pain at the infusion site, and chest tightness occurring within minutes of transfusion initiation represents a medical emergency requiring immediate cessation of transfusion. 1, 2

Immediate Clinical Reasoning

The timing and symptom constellation are critical here:

• Fever with chest tightness and pain occurring within minutes strongly suggests a severe acute transfusion reaction rather than a benign febrile non-hemolytic reaction 1, 3
• Severe infusion reactions occur immediately after infusion starts and are characterized by hypotension, chest tightness, respiratory distress, dyspnea, bronchospasm, laryngeal edema, urticaria, or rash 4
• Bacterial contamination from platelets presents with isolated fever within 6 hours and represents a leading cause of transfusion-related mortality 1, 3

Why Not Febrile Non-Hemolytic Reaction (Option A)

While FNHTR is the most common transfusion reaction, the presence of chest tightness and pain at the infusion site within minutes makes this diagnosis unlikely and potentially dangerous to assume 1, 2:

• FNHTR typically presents with isolated fever without hemodynamic compromise 5
• The critical pitfall is dismissing fever as "just FNHTR" without excluding life-threatening causes, particularly bacterial contamination and acute hemolytic reactions 1, 3
• General anesthesia and critical illness can mask early signs of serious reactions, making it essential not to continue transfusion despite "just fever" 1

Why Not Simple Allergic Reaction (Option D)

Allergic reactions typically present with:

• Urticaria, pruritus, and rash as predominant features 4
• Mild to moderate allergic reactions consist of nausea, fever, erythema, and itching that resolve with reduction of infusion rate 4
• The presence of chest tightness suggests anaphylaxis or a more severe reaction rather than simple allergic reaction 4, 2

Distinguishing Hemolytic Reaction from Bacterial Contamination

Acute Hemolytic Reaction Features:

• Occurs during or within 24 hours of transfusion due to incompatible red blood cells 6, 5
• Clinical presentation includes hypotension, tachycardia, hemoglobinuria, fever, chest pain, and back pain 2, 6
• Risk is approximately 1:70,000 per unit 6
• Pathophysiology involves complement activation, cytokine release causing systemic inflammatory response, and DIC 6

Bacterial Contamination Features:

• Fever within 6 hours after platelet transfusion is a leading cause of transfusion-related mortality 1, 3
• Can present with isolated fever initially, progressing to septic shock 1, 3
• Requires immediate broad-spectrum antibiotics after blood cultures 1

Required Immediate Actions

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

1. Notify the transfusion laboratory/blood bank immediately 1, 2
2. Check patient identification and blood component compatibility labels for clerical errors 1
3. Assess vital signs: heart rate, blood pressure, respiratory rate, oxygen saturation, repeat temperature 1, 2
4. Perform focused assessment for hemodynamic instability (hypotension, tachycardia) which indicates serious reaction 1

Diagnostic Workup

Send the blood component bag with administration set back to transfusion laboratory 1:

• Collect post-reaction blood samples for repeat crossmatch and direct antiglobulin test (Coombs test) 1
• Complete blood count and blood cultures if bacterial contamination suspected 1
• Visual inspection of plasma for hemolysis 1
• Urine analysis for hemoglobinuria 1, 2

Management Based on Suspected Diagnosis

If Hemolytic Reaction Suspected:

• Aggressive fluid resuscitation to maintain urine output >100 mL/hour 1
• Monitor for DIC with coagulation studies 6
• Provide oxygen and vasopressor support as needed 1

If Bacterial Contamination Suspected:

• Obtain blood cultures before antibiotics 1
• Initiate broad-spectrum antibiotics immediately after cultures 1
• Aggressive supportive care for septic shock 1

Critical Pitfalls to Avoid

• Never continue the transfusion despite "just fever"—general anesthesia and critical illness mask early signs of serious reactions 1
• Never assume fever is always FNHTR—bacterial contamination can present with isolated fever and is potentially fatal 1
• Never restart transfusion before laboratory clearance, even if symptoms improve, as the reaction may worsen with continued exposure 1
• In postoperative patients, maintain high suspicion as diagnosis during ongoing hemorrhage may be difficult 2