What is the most common cause of jaw pain in a patient undergoing blood transfusion?

Acute Hemolytic Transfusion Reaction

The most common cause of jaw pain (specifically pain at the IV site, chest, back, or trunk) during blood transfusion is an acute hemolytic transfusion reaction, which represents a medical emergency requiring immediate cessation of the transfusion. 1

Clinical Recognition

The characteristic presentation includes a clinical triad occurring within 10 minutes of blood transfusion 1:

• Pain at the IV site, chest, back, or trunk (the jaw pain you're asking about falls into this category of acute pain)
• Difficulty breathing or dyspnea
• Fever

This triad distinguishes acute hemolytic transfusion reaction from other transfusion complications 1. The pain component is sudden and intense, typically affecting the back, trunk, joints, or transfusion site itself 2.

Pathophysiology

Acute hemolytic transfusion reactions occur when ABO-incompatible blood is transfused, with a risk of approximately 1:70,000 per unit 3. The reaction triggers 3:

• Complete complement activation leading to intravascular hemolysis
• Formation of anaphylatoxins causing systemic inflammatory response
• Activation of the kinin system and intrinsic clotting cascade
• Release of cytokines producing the acute pain and systemic symptoms

Even small amounts of incompatible blood can initiate devastating consequences 4.

Immediate Management Algorithm

Step 1: Stop the transfusion immediately and maintain IV access with normal saline 1, 5

Step 2: Assess vital signs every 5-15 minutes, looking specifically for 1, 5:

• Hypotension or tachycardia (suggests hemolytic reaction)
• Respiratory distress
• Fever
• Hemodynamic instability

Step 3: Notify the blood bank immediately and check patient identification and blood component compatibility labels for clerical errors 5

Step 4: Obtain urgent laboratory studies 1, 5:

• Send the blood component bag with administration set back to transfusion laboratory
• Collect post-reaction blood samples for repeat crossmatch and direct antiglobulin test (Coombs test)
• Visual inspection of plasma for hemolysis
• Urine analysis for hemoglobinuria (dark urine)
• Complete blood count
• Blood cultures if bacterial contamination suspected

Step 5: Initiate supportive care 1, 5:

• High-flow oxygen
• Aggressive IV fluid resuscitation to maintain mean arterial pressure >65-70 mmHg
• Maintain urine output >100 mL/hour to prevent renal failure
• Vasopressors if needed for persistent hypotension

Critical Differential Considerations

While acute hemolytic transfusion reaction is the primary concern with acute pain during transfusion, other reactions present differently 1, 6:

• Febrile non-hemolytic reaction: Isolated fever and chills without the characteristic pain at IV site or acute respiratory distress (incidence 1.1-2.15%) 1
• Allergic reaction: Urticaria, pruritus, skin flushing rather than IV site pain; respiratory symptoms from bronchospasm, not systemic inflammation 1
• Bacterial contamination: Fever within 6 hours (especially with platelets), but typically without the acute pain component 6, 5
• TRALI: Fever, hypoxemia, dyspnea within 1-2 hours, but pain is not a primary feature 6

Common Pitfalls to Avoid

• Never continue the transfusion despite "just pain," as general anesthesia and critical illness can mask early signs of serious reactions 5
• Do not restart the transfusion before laboratory clearance, even if symptoms improve, as the reaction may worsen with continued exposure 5
• Do not assume this is simply an "acute pain transfusion reaction" (APTR) until all life-threatening causes have been excluded—APTR is a diagnosis of exclusion 2
• Do not delay treatment waiting for laboratory confirmation; the mortality risk is 1:1,250,000 RBC units transfused, but immediate action can prevent progression to DIC, renal failure, and shock 1, 3

The key distinguishing feature is the timing (within 10 minutes) and the triad of pain, dyspnea, and fever occurring together during active transfusion 1.