What investigations are recommended for a snake bite?

Recommended Investigations for Snake Bite

Emergency services should be activated immediately for any person bitten by a venomous or possibly venomous snake. 1, 2

Initial Assessment and Diagnostic Work-up

• Obtain a detailed history including time of bite, snake description (if possible), and any symptoms experienced since the bite 2
• Physical examination focusing on the bite site for fang marks, swelling, ecchymosis, and pain 3
• Remove rings and other constricting objects from the bitten extremity to prevent damage from swelling 1, 2
• Rest and immobilize the bitten extremity to minimize venom absorption 1, 2

Laboratory Investigations

• Complete blood count (CBC) with special attention to platelet count to detect thrombocytopenia 3, 4
• Coagulation studies including:
  • Prothrombin time (PT)/International Normalized Ratio (INR) 5, 4
  • Activated partial thromboplastin time (aPTT) 5, 4
  • Fibrinogen levels 4
  • Fibrinogen degradation products 3
• Basic metabolic panel to assess renal function 3, 5
• Creatine kinase (CK) to evaluate for myotoxicity 5, 4
• Liver function tests 5
• Urinalysis to check for hematuria or myoglobinuria 5

Serial Monitoring

• Repeat coagulation studies, CBC, and CK every 4-6 hours for the first 24 hours 5, 4
• Monitor for development of neurotoxicity with serial neurological examinations 5
• Track progression of local tissue swelling by marking and measuring the advancing edge 6

Special Considerations

• For suspected pit viper envenomation (rattlesnakes, copperheads, cottonmouths), monitor closely for coagulopathy and tissue damage 1, 4
• For suspected coral snake or other elapid envenomation, monitor closely for neurotoxic effects 2
• Snake Venom Detection Kit may be useful in regions with multiple venomous snake species to guide antivenom selection 5

Severity Assessment

• Factors associated with severe envenomation include:
  • Time from bite to care of 6 or more hours 4
  • Patient younger than 12 years 4
  • Large snake size 4
  • Presence of ptosis (drooping eyelid) 4
  • Initial hypofibrinogenemia 4
  • Initial thrombocytopenia 4

Harmful Practices to Avoid

• Do NOT apply ice to the bite wound 1, 2
• Do NOT use suction devices (with or without incision) 1, 2
• Do NOT apply electric shock 1, 2
• Do NOT apply tourniquets 1, 2
• Do NOT use pressure immobilization bandaging in North America 1, 2

Hospital Preparedness

• All patients with suspected snakebite should be admitted for at least 12 hours of observation 5
• Hospitals should stock appropriate antivenom based on local snake species 7
• Ensure availability of equipment for managing potential complications including anaphylaxis, airway compromise, and shock 7, 5