Mechanism of Caustic Injury from Ingested Batteries
Ingested batteries cause tissue injury through three distinct mechanisms: pressure necrosis from direct contact, electrical burns from current generation, and chemical injury from alkaline hydroxide production at the cathode. 1
Primary Injury Mechanisms
Electrical Current Generation
- The battery generates an electrical current when in contact with moist tissue, creating an electrochemical circuit that produces caustic substances at both poles. 2
- The cathode (negative pole) produces alkaline hydroxide, while the anode (positive pole) generates acid through secondary chemical reactions. 2
- Alkaline injury at the cathode is significantly more severe than acidic injury at the anode, causing deeper tissue penetration and more extensive damage to surrounding structures. 2
- The direction of battery placement critically determines injury pattern—when the cathode faces the trachea, complications affecting neighboring tissues are more severe. 2
Chemical Burns
- The alkaline hydroxide (potassium or sodium hydroxide) produced at the cathode causes liquefactive necrosis, which is the predominant mechanism of severe tissue damage. 3
- This chemical injury can begin as early as one hour after impaction and rapidly progresses to involve all muscular layers by four hours. 3
- The caustic material continues to cause injury even after battery removal, as the alkaline substance penetrates deeper tissue layers. 3
Pressure Necrosis
- Direct mechanical compression from the battery against the esophageal wall contributes to ischemic injury. 1
- This pressure effect is compounded by the electrical and chemical mechanisms, accelerating tissue breakdown. 1
Temporal Progression of Injury
- Mucosal damage is visible within 1 hour of impaction. 3
- Full-thickness muscular involvement occurs by 4 hours. 3
- Severe burns with potential perforation, tracheoesophageal fistula formation, and vascular injury can develop within 6-22 hours. 3
Clinical Implications
The triple mechanism of injury (electrical, chemical, and pressure) explains why battery ingestions require emergent endoscopic removal within 2 hours, and at latest within 6 hours, unlike other foreign bodies. 1 The alkaline-dominant injury pattern means that even small batteries can cause catastrophic complications including esophageal perforation, tracheoesophageal fistula, and aortic fistula formation. 3, 4
Critical Pitfall
The severity of injury does not correlate with battery size or voltage—even 1.35-1.5V batteries can cause severe full-thickness burns and life-threatening complications. 3, 5 Low-voltage batteries are equally dangerous because the injury mechanism depends primarily on the electrochemical generation of caustic hydroxides, not the voltage itself. 2