What is the best course of action for a 37-year-old female with a 2-week history of intermittent mild dull ache in her right calf, worsening at night, without swelling, redness, or fever, and with a visible blue vein on the opposite side of the same calf?

Clinical Assessment and Management

This patient has a low pretest probability for DVT (Wells score <2) and most likely has superficial venous insufficiency or a benign musculoskeletal condition; however, you should obtain a D-dimer test and if negative, no further workup is needed, but if positive, proceed to complete duplex ultrasound to definitively exclude DVT. 1, 2

Risk Stratification Using Wells Score

Calculate the Wells score systematically to guide your diagnostic approach: 1

This patient scores -1 point:

• Active cancer: 0 points (none mentioned) 1
• Recent immobilization/surgery: 0 points (none mentioned) 1
• Localized tenderness along deep venous system: 0 points (dull ache, not tenderness) 1
• Entire leg swollen: 0 points (no swelling noted) 1
• Calf swelling ≥3 cm vs other side: 0 points (no swelling) 1
• Pitting edema: 0 points (no swelling) 1
• Collateral superficial veins: 0 points (single visible blue vein is not collateral circulation) 1
• Previous DVT: 0 points (none mentioned) 1
• Alternative diagnosis at least as likely: -2 points (superficial venous insufficiency or musculoskeletal pain more likely) 1

A Wells score <2 indicates low pretest probability for DVT. 1

Recommended Diagnostic Pathway for Low Probability DVT

For low pretest probability patients, begin with D-dimer testing rather than proceeding directly to ultrasound: 2

• If D-dimer is negative, no further testing is needed and DVT is effectively ruled out 2
• If D-dimer is positive, proceed to complete duplex ultrasound (CDUS) from inguinal ligament to ankle, including calf veins 1, 2
• Do not use limited proximal-only ultrasound, as this requires repeat imaging in 5-7 days to safely exclude calf DVT 1

Most Likely Alternative Diagnoses

The visible blue vein suggests superficial venous pathology rather than deep venous thrombosis: 3, 4

Superficial venous insufficiency/varicose veins:

• Presents with visible dilated superficial veins, dull aching pain worse at end of day or night, and absence of acute inflammatory signs 3, 4
• The prevalence of isolated superficial venous reflux without deep venous involvement is 76-78% in patients with visible venous changes 4
• Pain pattern (worse at night, intermittent) is consistent with venous congestion rather than acute thrombosis 3, 4

Musculoskeletal causes:

• Mild muscle strain or overuse can present with intermittent dull ache without visible injury 5, 3
• Absence of swelling, redness, and fever makes inflammatory or infectious causes unlikely 3

Critical Clinical Pitfalls to Avoid

Do not skip objective testing based solely on clinical assessment: Even though this patient appears low risk, approximately 70% of patients referred for suspected DVT do not have it, but 30% do, emphasizing the need for objective confirmation 6, 7

Do not assume visible superficial veins exclude DVT: While superficial venous insufficiency is more likely, 22% of patients with primary superficial venous reflux can have concurrent deep venous insufficiency 4

Do not ignore persistent or worsening symptoms: If symptoms progress, develop swelling, or the patient develops new risk factors (immobilization, surgery, trauma), reassess with ultrasound regardless of initial D-dimer result 1, 2

When to Proceed Directly to Ultrasound

Bypass D-dimer testing and obtain immediate CDUS if any of the following develop: 2

• New leg swelling appears 2
• Pain becomes severe or localized along deep venous distribution 1, 2
• Patient develops DVT risk factors (surgery, immobilization, cancer diagnosis) 1, 2
• Symptoms persist beyond 2 weeks despite conservative management 1, 2

Management if DVT is Excluded

Once DVT is ruled out, address the likely superficial venous insufficiency: 1

• Compression stockings (20-30 mm Hg) for symptom relief 1
• Leg elevation when resting 5
• Avoid prolonged standing 1
• Consider vascular surgery referral if symptoms significantly impact quality of life 1