What's the next step for an elderly patient with persistent swelling and pain on the top of their left foot, despite negative DVT (Deep Vein Thrombosis) ultrasound and normal lab results?

Evaluation for Non-DVT Foot Swelling and Pain

With DVT excluded by ultrasound and normal labs, you should obtain X-rays of the left foot to evaluate for fracture, arthritis, or bone pathology, and if negative, consider MRI to assess for soft tissue injury, tendonitis, or occult stress fracture. 1, 2

Why DVT Workup is Complete

• A negative ultrasound performed a few days ago effectively excludes acute DVT in the proximal veins at that time point 1
• The American College of Chest Physicians guidelines state that repeat imaging is only indicated when symptoms persist or worsen despite negative initial workup, or when there is high clinical suspicion for iliocaval DVT (which presents with whole-leg swelling, not isolated dorsal foot swelling) 3, 2
• Isolated dorsal foot swelling is not a typical presentation of DVT, which classically causes calf or entire leg swelling 3, 4
• Normal labs (presumably including D-dimer if checked) further support that acute thrombosis is not the cause 1

Differential Diagnosis for Dorsal Foot Swelling

Musculoskeletal Causes (Most Likely)

• Stress fracture of metatarsals or midfoot bones, particularly in elderly patients with osteoporosis or recent increased activity 5
• Osteoarthritis or inflammatory arthritis affecting midfoot joints 5
• Extensor tendonitis or tenosynovitis of the dorsal foot tendons 5
• Lisfranc injury or midfoot sprain, even from minor trauma that patient may not recall 5

Other Considerations

• Gout or pseudogout affecting midfoot joints (though labs were normal, uric acid may not have been checked) 5
• Cellulitis without systemic signs (though this typically presents with erythema and warmth) 4
• Ganglion cyst or soft tissue mass causing localized swelling 2
• Superficial thrombophlebitis of dorsal foot veins (less common location but possible) 2, 6

Recommended Diagnostic Algorithm

First-Line Imaging

• Order weight-bearing X-rays of the left foot (AP, lateral, and oblique views) to evaluate for:
  • Fractures (acute or healing stress fractures) 5
  • Degenerative joint disease 5
  • Bone lesions or osteomyelitis 5
  • Soft tissue swelling patterns 5

Second-Line Imaging (If X-rays Negative)

• Order MRI of the left foot without contrast if X-rays are unrevealing but symptoms persist, to evaluate for: 2
  • Occult stress fractures not visible on plain films 2
  • Tendon pathology (tendonitis, partial tears) 2
  • Soft tissue masses or fluid collections 2
  • Bone marrow edema suggesting early stress injury 2
  • Ligamentous injuries 2

Additional Laboratory Testing (If Not Already Done)

• Uric acid level if gout is suspected clinically 5
• ESR and CRP if inflammatory arthritis is a consideration 5

When to Refer

Orthopedic Referral

• Refer to orthopedics or podiatry if imaging reveals fracture, significant arthritis, or structural abnormality requiring specialized management 2
• Consider referral if conservative management fails after 4-6 weeks 2

Rheumatology Referral

• Refer to rheumatology if inflammatory markers are elevated and inflammatory arthritis is suspected 5

Vascular Surgery Referral (Unlikely Needed)

• Only consider if there are signs of chronic venous insufficiency or if repeat ultrasound (not currently indicated) shows unexpected findings 2, 6

Critical Pitfalls to Avoid

• Do not repeat ultrasound for DVT unless new symptoms develop suggesting proximal extension (entire leg swelling, thigh pain) or iliocaval involvement 3, 2
• Do not assume "normal labs" excludes all pathology—ensure specific tests like uric acid were actually checked if gout is suspected 5
• Do not overlook stress fractures in elderly patients, which may not be visible on initial X-rays and require MRI or repeat X-rays in 2-3 weeks 2
• Do not delay imaging—persistent localized foot swelling and pain for several days warrants objective evaluation beyond clinical examination 5, 4
• Do not miss compartment syndrome if pain is severe and out of proportion to examination findings, though this is rare in the dorsal foot and typically presents acutely 4