What is the most appropriate immediate management for a diabetic patient presenting with an inflamed, tender leg?

Immediate Management: Complete Blood Count (CBC)

For a diabetic patient presenting with an inflamed, tender leg, the most appropriate immediate management is to obtain a CBC (Option A) as part of the initial assessment to evaluate for systemic infection, while simultaneously performing clinical examination, wound debridement, and obtaining wound cultures. However, this represents only one component of a comprehensive immediate approach that must include multiple simultaneous interventions.

Algorithmic Approach to Immediate Management

Step 1: Clinical Assessment and Infection Classification

• Assess for systemic toxicity immediately: Check for fever, tachycardia, hypotension, confusion, leukocytosis, acidosis, or severe hyperglycemia, as these indicate severe infection requiring hospitalization 1, 2
• Classify infection severity clinically: Document presence of ≥2 inflammatory signs (erythema, warmth, swelling, tenderness, pain, purulent discharge) to confirm infection 2, 3
• Determine if cellulitis extends >2 cm from any wound, as this indicates at minimum moderate infection 1
• Note that 50% of limb-threatening diabetic foot infections lack systemic signs, so absence of fever does not exclude severe disease 1, 3

Step 2: Immediate Diagnostic Testing (Including CBC)

• Obtain CBC with differential to assess for leukocytosis and systemic inflammatory response 2
• Obtain blood cultures if severe infection or systemic illness is present 1, 4
• Order plain radiographs immediately to evaluate for osteomyelitis, foreign bodies, or gas in soft tissues 2

Step 3: Urgent Wound Management

• Perform immediate surgical debridement of all necrotic tissue before obtaining culture specimens 1, 3
• Obtain tissue specimens from debrided wound base via curettage or biopsy (not swabs) for aerobic and anaerobic cultures 1, 4
• Probe the wound to assess depth and involvement of deeper structures 1

Step 4: Hospitalization Decision

Hospitalize immediately if ANY of the following are present 1, 2:

• Systemic toxicity (fever, leukocytosis, tachycardia, hypotension)
• Metabolic instability (severe hyperglycemia, acidosis, azotemia)
• Rapidly progressive or deep-tissue infection
• Substantial necrosis or gangrene
• Critical limb ischemia
• Inability to perform self-care

Step 5: Initiate Empirical Antibiotic Therapy

• Start broad-spectrum IV antibiotics immediately after cultures for moderate-to-severe infections 2, 3
• First-line options include piperacillin-tazobactam, amoxicillin-clavulanate, or ciprofloxacin plus clindamycin 2, 5
• Always cover Staphylococcus aureus (including MRSA if risk factors present) and consider gram-negative/anaerobic coverage for chronic or severe infections 5, 6, 7

Step 6: Metabolic Stabilization

• Correct hyperglycemia aggressively with insulin 2
• Restore fluid and electrolyte balance 1, 2

Why Not the Other Options?

Surgical Exploration (Option B)

• Surgical consultation is urgent but not the first step unless there is deep abscess, extensive bone/joint involvement, crepitus, substantial necrosis/gangrene, or necrotizing fasciitis 2, 3
• Bedside debridement precedes formal surgical exploration in most cases 1

MRI of the Site (Option C)

• MRI is the most sensitive imaging for osteomyelitis and deep abscesses but is not immediate management 2
• Plain radiographs should be obtained first; MRI is reserved for when plain films are inconclusive or deep infection is suspected 2, 8

CT Abdomen (Option D)

• CT abdomen is irrelevant for a leg infection and would delay appropriate care 1

Critical Pitfalls to Avoid

• Do not delay antibiotic therapy while waiting for imaging beyond plain radiographs 2, 3
• Do not obtain wound swabs from undebrided ulcers, as these are contaminated with colonizing organisms and provide misleading culture results 1, 4
• Do not assume absence of fever means mild infection, as half of limb-threatening infections lack systemic signs 1, 3
• Do not treat as outpatient if any hospitalization criteria are met, as this significantly increases amputation risk 1, 2

Definitive Answer Context

While CBC (Option A) is technically correct as part of immediate laboratory assessment, the question's framing is somewhat misleading because immediate management of an infected diabetic leg requires simultaneous multiple interventions: clinical assessment, CBC and blood cultures, wound debridement with tissue culture, plain radiographs, hospitalization decision, metabolic stabilization, and empirical antibiotics 1, 2, 3. The CBC alone is insufficient but represents the most appropriate single test among the options provided.