What is the appropriate evaluation and management for a patient, particularly an elderly or immobile individual with a history of bleeding disorders, recent surgeries, or infections, presenting with fever, bruising, and pain in the leg, to rule out conditions such as Deep Vein Thrombosis (DVT) or infection?

Evaluation and Management of Fever, Bruising, and Leg Pain

Immediate Diagnostic Priority: Rule Out Life-Threatening Infection and DVT

This patient requires urgent evaluation for both deep vein thrombosis (DVT) and limb-threatening infection, as the combination of fever, bruising (ecchymoses), and leg pain represents potential medical emergencies that can lead to limb loss or death if not promptly diagnosed and treated.

Initial Clinical Assessment

Red Flag Signs Requiring Urgent Surgical Consultation

The presence of extensive ecchymoses or petechiae combined with fever constitutes a sign of possibly imminently limb-threatening infection that mandates urgent surgical evaluation 1. Additional concerning features to assess immediately include:

• Pain out of proportion to clinical findings - suggests necrotizing infection or compartment syndrome 1
• Evidence of systemic inflammatory response (fever, tachycardia, hypotension) - indicates severe infection 1
• Rapid progression of symptoms - suggests aggressive infection 1
• Crepitus on examination - indicates gas-forming infection requiring emergency surgery 1
• New onset wound anesthesia - suggests tissue necrosis 1

Critical Pitfall to Avoid

The absence of fever or leukocytosis should not dissuade you from considering surgical exploration if other concerning features are present 1. Do not be falsely reassured by normal inflammatory markers.

Diagnostic Algorithm

Step 1: Assess DVT Probability Using Wells Score

• Calculate Wells score to stratify DVT probability as "unlikely" or "likely" 1, 2
• If Wells score indicates "likely" DVT, proceed directly to imaging without D-dimer testing 2
• If Wells score indicates "unlikely" DVT, obtain D-dimer first 2

Step 2: Imaging Strategy for DVT

Order comprehensive duplex ultrasound from inguinal ligament to ankle, including posterior tibial and peroneal veins in the calf, with compression and Doppler evaluation 3. This is superior to proximal-only ultrasound given the severity of symptoms 3, 4.

If Standard Ultrasound is Negative but Symptoms Persist:

• Image the iliac and pelvic veins with CT or MR venography 3, 4
• Extensive unexplained leg swelling with normal compression ultrasound suggests iliocaval DVT that standard ultrasound misses 3, 4
• Do not accept limited proximal-only ultrasound - this is a critical pitfall that misses isolated iliac DVT 3, 4

Step 3: Evaluate for Infection

Immediate Surgical Consultation Required If:

• Extensive ecchymoses or petechiae are present (as in this patient) 1
• Fever with leg pain and bruising suggests possible necrotizing soft tissue infection 1
• Any signs from Table 12 of limb-threatening infection are present 1

Imaging for Infection:

• Obtain soft tissue imaging (ultrasound, CT, or MRI) to evaluate for abscess or deep-space infection 1
• Look for gas in deeper tissues on imaging - this requires emergency surgical debridement 1

Management Based on Findings

If DVT is Confirmed:

Proximal DVT:

• Initiate anticoagulation immediately with low-molecular-weight heparin or direct oral anticoagulant 3, 5, 6
• Direct oral anticoagulants (DOACs) are preferred over warfarin as they are at least as effective, safer, and more convenient 5
• For provoked DVT, treat for 3 months 3

Isolated Distal (Below-Knee) DVT:

• For severe symptoms, initiate anticoagulation rather than surveillance 3
• Anticoagulation reduces recurrent VTE risk (RR 0.34) and DVT recurrence (RR 0.25) compared to no treatment 7

Extensive Iliofemoral DVT:

• Consider thrombolytic therapy if no contraindication exists 8
• Refer to vascular surgery if symptoms are severe or refractory to anticoagulation 3

If Limb-Threatening Infection is Confirmed:

• Urgent surgical debridement is required for gas in tissues, abscess, or necrotizing fasciitis 1
• Prompt and adequate surgical debridement may decrease the likelihood that extensive amputation is needed 1
• Start broad-spectrum antibiotics immediately while awaiting surgical intervention 1

If Ischemia is Present:

• Refer to vascular surgeon early to consider revascularization, especially if critically ischemic 1
• Lower extremity atherosclerosis may be amenable to angioplasty or vascular bypass 1

Alternative Diagnoses to Consider

If DVT and infection are excluded:

• Baker's cyst rupture - can be identified on ultrasound 3
• Superficial thrombophlebitis - presents with localized cord-like tenderness 2
• Cellulitis - typically with erythema and warmth 1
• Acute lymphoblastic leukemia (ALL) - can present with leg pain, fever, and bruising, particularly in children or young adults 9
• Chronic venous insufficiency - if bilateral presentation 4

Critical Pitfalls Summary

• Do not delay imaging or surgical consultation - fever with bruising and leg pain requires urgent evaluation 1, 3
• Do not miss iliocaval DVT by accepting limited ultrasound when symptoms are extensive 3, 4
• Do not be falsely reassured by absence of fever or leukocytosis when considering surgical exploration 1
• Do not overlook necrotizing infection - extensive ecchymoses with fever is a red flag 1
• Do not use D-dimer alone in high-probability patients or hospitalized patients 2, 4