What dose of apixaban (elixaban) should be given to a patient with a suspected Deep Vein Thrombosis (DVT) and a Wells score of 1 until Doppler ultrasound results are available the next morning?

Empiric Anticoagulation for Suspected DVT with Wells Score of 1

For a patient with suspected DVT, Wells score of 1 (low probability), and Doppler unavailable until tomorrow morning, you should NOT initiate empiric anticoagulation and can safely wait for diagnostic imaging within 24 hours. 1

Risk Stratification and Treatment Algorithm

Wells Score of 1 = Low Clinical Suspicion

• A Wells score of 1 indicates low pretest probability of DVT 2, 3
• The American College of Chest Physicians explicitly recommends withholding parenteral anticoagulants while awaiting diagnostic test results in patients with low clinical suspicion, provided test results are expected within 24 hours 1
• This recommendation applies to both outpatient and inpatient settings 1

Critical Time Window

• If Doppler available within 24 hours: Do NOT start anticoagulation 1
• If Doppler delayed >24 hours: Consider starting empiric anticoagulation even with low Wells score 1
• If intermediate suspicion (Wells 2) AND delay >4 hours: Start empiric anticoagulation 1, 4
• If high suspicion (Wells ≥3): Start empiric anticoagulation immediately regardless of imaging availability 1, 4

If You Must Treat (Against Guidelines for Wells Score 1)

If clinical judgment dictates empiric treatment despite low Wells score, use standard treatment-dose anticoagulation, NOT prophylactic dosing:

Apixaban Dosing for Suspected DVT

• 10 mg orally twice daily until Doppler results available 5
• This is the FDA-approved treatment dose for acute DVT, NOT the 2.5 mg prophylactic dose 5
• After DVT is confirmed and first 7 days completed, reduce to 5 mg twice daily 5

Alternative Parenteral Options (Preferred by Guidelines)

• Low-molecular-weight heparin (LMWH): Most commonly recommended first-line agent 1, 4
• Fondaparinux: Alternative to LMWH 1, 4
• Unfractionated heparin (IV or subcutaneous): Particularly for severe renal impairment 1, 4

Common Pitfalls to Avoid

Do NOT Use Prophylactic Dosing

• Never use apixaban 2.5 mg twice daily for suspected acute DVT—this is only for extended secondary prevention after completing initial treatment 1, 5
• The 2.5 mg dose is for post-surgical prophylaxis or extended therapy after 6 months of treatment, NOT for acute suspected DVT 5

Wells Score Limitations in Your Patient

• Wells score performs poorly in hospitalized patients (failure rate 5.9% in low-risk inpatients) 6
• If your patient is hospitalized, consider this limitation when deciding whether to treat empirically 6
• The score was validated primarily in outpatient settings 2, 6

Risk-Benefit Consideration

• With Wells score of 1, the probability of proximal DVT is approximately 5.9-7.8% 2, 6
• Untreated proximal DVT carries 25-30% mortality risk from pulmonary embolism 1
• However, unnecessary anticoagulation exposes patients to bleeding risk 1
• The 24-hour wait for imaging is considered safe and standard of care for low-probability patients 1

D-Dimer Testing

• If available, a negative D-dimer combined with Wells score ≤1 can safely exclude DVT without imaging 2
• This combination reduces unnecessary ultrasounds by approximately 50% 2
• However, D-dimer has limited utility in hospitalized patients and those with recent surgery, trauma, or cancer 1, 2

What Happens Tomorrow After Doppler

If Proximal DVT Confirmed

• Continue apixaban 10 mg twice daily for 7 days total, then reduce to 5 mg twice daily 5
• Minimum 3 months treatment for provoked DVT 1, 4
• Consider extended therapy for unprovoked DVT 1, 4

If Distal DVT Only (Below Popliteal Vein)

• Either treat with same regimen as proximal DVT OR perform serial imaging at 1 week 1, 4
• Approximately 10-15% of distal DVTs extend proximally within 2 weeks if untreated 4

If Negative Doppler

• Stop anticoagulation immediately 1
• No further treatment needed unless symptoms persist or worsen 1