Management of Accidental Formalin Ingestion
Formalin ingestion is a medical emergency requiring immediate supportive care, with treatment focused on gastrointestinal decontamination, acid-base correction, and organ support. Fomepizole is not indicated for formalin poisoning as it specifically targets alcohol dehydrogenase inhibition for ethylene glycol and methanol toxicity, not formaldehyde metabolism. 1
Initial Assessment and Management
- Immediately assess airway, breathing, and circulation, as formalin ingestion can cause rapid deterioration with metabolic acidosis and multiorgan dysfunction 2
- Contact Poison Control Center to evaluate systemic toxicity of the ingested agent 1
- Perform laboratory evaluation including complete blood count, serum electrolytes, liver function tests, arterial blood gases, and renal function tests to assess the severity of poisoning 1
- Monitor for severe metabolic acidosis (pH < 7.20), which indicates severe toxicity and poor prognosis 2, 3
Gastrointestinal Decontamination
- If presentation is within 1 hour of ingestion, consider activated charcoal (standard dose 1g/kg orally) to limit absorption 1
- Avoid gastric lavage if corrosive injury is suspected, as it may increase risk of perforation 1
- Early endoscopy should be considered to assess the extent of corrosive injury to the upper gastrointestinal tract 1
Supportive Care
- Aggressive fluid resuscitation to maintain hemodynamic stability and prevent hypovolemic shock 4
- Correct metabolic acidosis with intravenous sodium bicarbonate 4, 2
- Provide gastro-protection with proton pump inhibitors or H2 blockers 4
- Monitor for and treat coagulopathy, which is common in severe formalin poisoning 2, 3
- Consider N-acetylcysteine administration, which has been used in case reports of formaldehyde poisoning 3
Role of Fomepizole
- Fomepizole is NOT indicated for formalin (formaldehyde) poisoning 5
- Fomepizole is specifically FDA-approved as an antidote for ethylene glycol or methanol poisoning by inhibiting alcohol dehydrogenase 5
- Formaldehyde metabolism does not primarily involve alcohol dehydrogenase, making fomepizole ineffective for this toxicity 5
Monitoring and Complications Management
- Monitor for development of acute kidney injury and provide renal support as needed 2, 3
- Watch for signs of respiratory distress and pulmonary edema, which can be fatal in formalin poisoning 2
- Assess for gastrointestinal perforation, which may require surgical intervention 1, 3
- Monitor for signs of liver dysfunction, as formaldehyde can cause hepatotoxicity 1
Surgical Considerations
- Surgical consultation should be obtained early if there are signs of perforation or extensive necrosis 1
- Up to 1-3% of patients with corrosive ingestions require surgery due to complications such as perforation, mediastinitis, or severe bleeding 1
- Esophagotomy with primary closure may be considered in cases with limited contamination 1
Prognosis and Follow-up
- Mortality is high in severe formalin poisoning, particularly with delayed treatment or development of pulmonary edema 2
- Survivors may require long-term follow-up for stricture formation and other gastrointestinal sequelae 3
- Psychiatric evaluation is recommended for intentional ingestions 1
Common Pitfalls
- Mistaking formalin poisoning for other toxic alcohol ingestions (methanol, ethylene glycol) and inappropriately administering fomepizole 5
- Delaying endoscopic evaluation, which can lead to missed opportunities for early intervention 1
- Underestimating the severity of injury, as initial symptoms may not correlate with the extent of damage 1
- Failing to monitor for delayed complications such as stricture formation or perforation 1, 3