Snake Envenomation (Ophitoxemia)
Forensic Toxicology: Clinical and Diagnostic Overview
1. Clinical Syndromes
Snake venom is a complex mixture of enzymes and proteins. Clinical presentation is categorized by the dominant toxin profile:
| Venom Type | Primary Manifestations |
|---|---|
| Neurotoxic | Descending paralysis, bilateral ptosis (early), ophthalmoplegia, respiratory failure (diaphragm paralysis). |
| Hemotoxic | Systemic coagulopathy, spontaneous bleeding (epistaxis, hematuria, gingival bleed), and shock. |
| Cytotoxic | Severe localized pain, progressive edema, blister formation, tissue necrosis (common in Viperid bites). |
2. Bedside & Diagnostic Assessment
- 20-Minute Whole Blood Clotting Test (20WBCT): The standard bedside test for venom-induced consumptive coagulopathy (VICC). Failure to form a clot indicates systemic hemotoxicity.
- Fang Marks: Classic indicator, but a lack of visible marks does not exclude envenomation.
- Observation: Patients should be monitored for at least 12-24 hours, as some symptoms (especially neurotoxicity) can have a delayed onset.
3. Forensic High-Yield Pearls
- Manner of Death: Almost exclusively accidental; however, forensic investigation must rule out rare cases of deliberate, forced exposure (homicide).
- Autopsy: Look for evidence of edema, local hemorrhage, and internal organ hemorrhage (especially in hemotoxic species).
- Resource: For management algorithms, antivenom protocols, and board-style questions, visit mymedschool.org.