A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 60-year-old man presents with pain, swelling, and a purulent discharge from his left foot. He says that the symptoms began 7 days ago with mild pain and swelling on the medial side of his left foot, but have progressively worsened. He states that there has been a foul-smelling discharge for the past 2 days. The medical history is significant for type 2 diabetes mellitus that was diagnosed 10 years ago and is poorly managed, and refractory peripheral artery disease that failed revascularization 6 months ago. The current medications include aspirin (81 mg orally daily) and metformin (500 mg orally twice daily). He has a 20-pack-year smoking history but quit 6 months ago. The family history is significant for type 2 diabetes mellitus in both parents and his father died of a myocardial infarction at 50 years of age. His temperature is 38.9°C (102°F); blood pressure 90/65 mm Hg; pulse 102/min; respiratory rate 22/min; and oxygen saturation 99% on room air. On physical examination, he appears ill and diaphoretic. The skin is flushed and moist. There is 2+ pitting edema of the left foot with blistering and black discoloration (see picture). The lower legs are hairless and the lower extremity peripheral pulses are 1+ bilaterally. Laboratory tests are pending. Blood cultures are positive for Staphylococcus aureus. Which of the following findings is the strongest indication for amputation of the left lower extremity in this patient?
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A
Diminished peripheral pulsesIncorrect. Diminished pulses indicate PAD severity and need for revascularization assessment but are not a stand-alone amputation indication.
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B
Positive blood culturesIncorrect. Bacteremia (positive cultures) mandates IV antibiotics but is not itself the indication for amputation.
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C
Presence of wet gangreneCorrect. wet gangrene with systemic toxicity is a surgical emergency, and urgent amputation is required to prevent fatal sepsis.
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D
Smoking historyIncorrect. Smoking is a major PAD risk factor but not an indication for amputation.
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E
Elevated hemoglobin A1cIncorrect. Poor glycemic control accelerates limb ischemia but elevated A1c itself is a chronic disease marker, not an acute surgical indication for amputation.
↑ Tap an answer to reveal the reasoning
Answer: C. This patient has a diabetic foot infection with limb-threatening features: poorly controlled diabetes, refractory peripheral artery disease, fever, hypotension/tachycardia (early septic shock), and a foot with blistering, black discoloration, and purulent malodorous drainage. Black discoloration with wet/exudative tissue and systemic toxicity is wet gangrene, where infection with anaerobic and/or aerobic bacteria liquefies necrotic tissue, producing a rapidly progressive cellulitis with putrid drainage.
Wet gangrene is a surgical emergency. Unlike dry gangrene (slow ischemic necrosis without significant bacterial load), wet gangrene seeds the bloodstream, can progress to gas gangrene/necrotizing fasciitis, and frequently triggers sepsis. The strongest indication for urgent amputation here is presence of wet gangrene with systemic toxicity, because debridement and antibiotics alone cannot control the infection once viable proximal tissue is overwhelmed.
Diminished pulses indicate disease severity but alone do not mandate amputation. Positive blood cultures with S. aureus indicate bacteremia requiring antibiotics but are not by themselves an amputation indication. Smoking is a risk factor for PAD progression but is not an indication for amputation.
**Why each option:**
**A.** Diminished pulses indicate PAD severity and need for revascularization assessment but are not a stand-alone amputation indication.
**B.** Bacteremia (positive cultures) mandates IV antibiotics but is not itself the indication for amputation.
**C.** Correct: wet gangrene with systemic toxicity is a surgical emergency, and urgent amputation is required to prevent fatal sepsis.
**D.** Smoking is a major PAD risk factor but not an indication for amputation.