Multistage Limb Salvage After Severe Cottonmouth (Agkistrodon piscivorus) Envenomation: A Case Report

Background: Cottonmouth envenomation typically produces prominent local tissue injury, with systemic toxicity occurring less commonly. We report a limb-threatening presentation with delayed deterioration after initial antivenom therapy. Methods: A man in his 50s sustained a suspected cottonmouth bite to the plantar midfoot and received 10 vials of Crotalidae immune F(ab′)2 (equine) antivenom during his initial hospitalization. Results: Five days after the bite, severe edema, progressive pain, paresthesia, pallor, delayed capillary refill, and nonpalpable pedal pulses raised clinical concern for delayed compartment syndrome and threatened tissue viability. Compartment pressures were not obtained. Operative drainage and debridement were independently indicated by plantar necrosis and suspected secondary infection after contaminated floodwater exposure. Surgery confirmed purulent fluid under pressure and nonviable tissue. The patient subsequently received adjunctive hyperbaric oxygen therapy, acellular fish-skin grafts, and definitive split-thickness skin grafting. Conclusions: This case underscores the importance of serial examinations and laboratory monitoring following pit viper envenomation, toxicology-guided antivenom management, careful distinction between suspected compartment syndrome and established necrosis or infection, and staged reconstruction for severe soft-tissue injury.