A 62-year-old woman entered the emergency department (ED) with a chief complaint of a snake envenomation to the left foot about one hour ago while hiking in a southwestern mountain trail. She reports the snake was small and tan and she did not see a rattle. The patient has no medical problems and states the pain in 2/10 and only present at the left foot.
On physical examination, the patient is in no acute distress. Her vital signs were as follows: temperature, 99.° F; pulse, 110 and regular; and blood pressure 100/65 mm Hg. Pulse oximetry on room air showed 100% saturation. Respiratory, cardiopulmonary, abdominal and neurological examinations were normal. Her left foot revealed 2 puncture marks at the left lateral mid foot with very mild swelling that did not ascend past the ankle. Skin was red and tender at the bite site and no neurological were present. No lymph node tenderness was present.
The patient had a WBC count of 12,100; hemoglobin, fibrinogen and platelet counts were normal.
At this point, the leading diagnoses dry bite from a rattlesnake or non-venous snake bite. The patient was discharged to home after the wound was cleaned and dressed. Tetanus status was updated and the patient was given a 7 day course of cephalaxin and told to see her physician in 5-7 days as needed.
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Dx: Snake Bite Patient Returns Within 24 Hours
Unfortunately, the patient returned within 24 hours with abdominal pain, increased leg swelling. Her vital signs were as follows: pulse, 140 and regular; and blood pressure 82/45 mm Hg. Pulse oximetry on room air showed 100% saturation. Her abdominal examination revealed diffuse tenderness with bilateral flank eccymosis. Her left foot revealed 2 puncture marks at the left lateral mid foot with moderate swelling to the groin with severe inguinal lymph node tenderness. Her hemoglobin was 6.4 gm/dl; fibrinogen 10 mg/dL; platelet count 2 per μl; prothrombin time > 60 seconds was. She was resuscitated and given 6 vials of Crofab Antivenin emergently and another 18 vials during her hospital course. An abdominal cat scan revealed retroperitoneal bleeding and underwent interventional radiological embolization. Because of active bleeding, she was transfused 8 units of PRBC’s over the next 8 hours. Her 10-day hospital course was complicated by a transfusion reaction, MRSA central line infection and healthcare associated pneumonia.
The patient was discharged with antibiotics. Although these wounds may appear frightening, acute infection is exceedingly rare.
Beyond the Bite:
The literature reports dry bites following rattlesnake envenomation as high as 20%. To call someone a dry bite, laboratory data (PT, Fibrinogen and platelets) should be normal or not trending worse 6-8 hours after envenomation.
Most rattlesnakes result in coagulopathy, thrombocytopenia and soft tissue swelling. The lower extremity can hide mild to moderate swelling and consideration should be given to observe all lower extremity envenomations for 12-24 hours.
Although mortality is rare from rattlesnake envenomation in the USA, the patient suffered significant morbidity by not being observed after the initial ED encounter. Her typical course had she been admitted after the first encounter would have likely been to receive Crofab Antivenin and be discharged within 1-2 days with repeat laboratory parameters and physical examination in 2-5 days after discharge.