A 26-year-old man comes to the emergency department with left ankle pain. He reports that he was playing golf, went to look for his ball in some tall grass, heard rattling, and then felt a sharp pain just above his left ankle 30 minutes ago. On examination, vital signs are normal. Two puncture marks are present just above his left lateral malleolus. There is mild edema, tenderness, and ecchymosis immediately surrounding the bite. Swelling to the rest of the lower leg is absent. Pulses and sensation in the left leg are intact. Laboratory studies reveal normal complete blood count, serum electrolytes, and coagulation panel. Repeat physical examination in 30 minutes reveals no interval change. Which of the following is the most appropriate course of action for this patient?

Question

A 26-year-old man comes to the emergency department with left ankle pain.  He reports that he was playing golf, went to look for his ball in some tall grass, heard rattling, and then felt a sharp pain just above his left ankle 30 minutes ago.  On examination, vital signs are normal.  Two puncture marks are present just above his left lateral malleolus.  There is mild edema, tenderness, and ecchymosis immediately surrounding the bite.  Swelling to the rest of the lower leg is absent.  Pulses and sensation in the left leg are intact.  Laboratory studies reveal normal complete blood count, serum electrolytes, and coagulation panel.  Repeat physical examination in 30 minutes reveals no interval change.  Which of the following is the most appropriate course of action for this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d1dc_86c9_bc81_97a8fc4a3952_MD0003_00 This patient was likely bitten by a rattlesnake (rattling, 2 fang marks) and has evidence of envenomation (swelling, ecchymosis, pain). The majority of medically significant snake bites in North America are due to rattlesnakes, cottonmouths, and copperheads. The venom varies by species and may contain toxins that cause local tissue injury (eg, severe tissue necrosis), damage nerves (eg, neurotoxicity) or muscles (eg, myotoxicity, cardiorespiratory complications), or affect hemostasis (eg, coagulation abnormalities, hemorrhage). Some of these effects (eg, muscle weakness, respiratory collapse) may be delayed by several hours. Mild, systemic manifestations (eg, nausea, diarrhea) may also occur. Evaluation of a patient with a snake bite includes: Immobilization of the affected limb: The wound should be examined and marked for evidence of progression. Appropriate laboratory studies: Coagulation studies (ie, platelet count, prothrombin time, partial thromboplastin time, INR, fibrinogen, D-dimer) should be repeated at frequent intervals. Administration of antivenom when indicated: The most commonly available antivenom (Crotalidae polyvalent immune Fab [Crofab]) contains immunoglobulin fragments that bind to and neutralize cottonmouth, copperhead, and rattlesnake venom toxins. However, it is expensive, not always readily available, and carries a risk of significant allergic (eg, hypersensitivity) reactions and recurrent coagulopathy. Indications for antivenom include unstable vital signs (eg, hypotension, tachypnea), rapidly progressing changes in wound, or abnormal coagulation studies. Due to the risk of life-threatening reactions, patients such as this one with mild envenomation (eg, mild, localized symptoms; normal vital signs; normal coagulation studies; normal pulses) should not receive antivenom (Choices B and D). However, they should be observed for 12-24 hours due to the risk of delayed toxicity. Repeat laboratory studies and close observation of the bite site should occur because symptoms can change and progress rapidly (Choice C). Educational objective: Patients with mild snake bite envenomation should be observed closely for 12-24 hours following the event. Repeat wound examinations and laboratory evaluation are important. Most medically significant snakebites in North America can be treated appropriately with antivenom if symptoms progress. References: Emergency treatment of a snake bite: pearls from literature. (http://www.ncbi.nlm.nih.gov/pubmed/19561988)

A 26-Year-Old Man Comes to the Emergency Department with Left