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8/17/2025 • 10–16 min read

DVT: Wells + Ultrasound & Outpatient DOAC Protocol

Deep vein thrombosis (DVT) can be diagnosed rapidly and safely using a pretest score, D-dimer where appropriate, and compression ultrasound. Most stable, low-risk patients can be treated at home with a direct oral anticoagulant (DOAC).

Typical Presentation

  • Unilateral leg swelling, pain, warmth, erythema; calf tenderness; dilated superficial veins.
  • Red flags for extensive clot: severe swelling/cyanosis, pain out of proportion (think phlegmasia), or PE symptoms (pleuritic pain, dyspnea, syncope).

Step 1 — Pretest Probability (Wells DVT score)

Use Wells to categorize patients into “DVT unlikely” vs “likely.”

  • DVT unlikely (low/intermediate): Get a high-sensitivity D-dimer. If negative → DVT excluded; no imaging needed in most adults.
  • DVT likely (high): Skip D-dimer; proceed straight to compression ultrasound and begin anticoagulation if safe.

Consider age-adjusted D-dimer thresholds in older adults when using assays standardized to 500 ng/mL FEU (cutoff ≈ age × 10).

Step 2 — Compression Ultrasound Strategy

  • Proximal scan (common femoral → popliteal): first-line in many pathways; detects clinically important DVT.
  • Whole-leg ultrasound picks up calf (distal) DVTs but may over-treat—use if follow-up is difficult or symptoms are distal.
  • Negative proximal scan but high suspicion: repeat proximal ultrasound in 5–7 days or do whole-leg ultrasound now.

Distal (Calf) DVT: Treat or Watch?

  • Low-risk, isolated distal DVT (no severe symptoms, no high-risk features): serial ultrasound at ~1 week (and 2 weeks if needed). Treat only if thrombus extends.
  • High-risk features (extensive clot, close to popliteal vein, active cancer, prior VTE, marked symptoms): anticoagulate as for proximal DVT.

Start Anticoagulation (who qualifies for home treatment?)

  • Stable vitals, no limb-threatening phlegmasia, low bleeding risk, good renal/hepatic function for chosen agent, and reliable follow-up.
  • Pregnancy/breastfeeding: use LMWH; avoid DOACs in pregnancy.
  • Cancer-associated VTE: DOACs or LMWH individualized by bleeding risk and drug interactions.

Outpatient DOAC Protocol (adults)

  • Apixaban: 10 mg twice daily for 7 days, then 5 mg twice daily. For extended prevention in select patients, 2.5 mg twice daily.
  • Rivaroxaban: 15 mg twice daily for 21 days, then 20 mg once daily with food. For extended prevention, 10 mg once daily in select patients.
  • Warfarin/LMWH: for mechanical valves, significant antiphospholipid syndrome, severe renal/hepatic disease, or cost/interaction constraints.

Dose by label and creatinine clearance (CrCl). Reconcile interacting meds (strong CYP3A4/P-gp inhibitors/inducers) before choosing a DOAC.

Duration of Therapy

  • Provoked by major transient risk (surgery, short-term immobilization): typically 3 months.
  • Unprovoked or persistent risk (thrombophilia, active cancer): consider extended/indefinite therapy if bleeding risk is acceptable.
  • Isolated distal DVT under surveillance: treat only if propagation or high-risk features appear.

Supportive Care & Follow-up

  • Early ambulation once anticoagulated; routine compression stockings are not required but may help edema in select patients.
  • Educate on bleeding precautions (falls, NSAIDs), warning signs of PE, and adherence (evening food with rivaroxaban).
  • Reassess at 1–2 weeks: symptoms, adherence, side effects; confirm plan for treatment length.

When to Escalate

  • Severe swelling/pain, cyanosis (phlegmasia), suspected propagation despite therapy, bleeding on anticoagulants, or new dyspnea/CP → evaluate for PE and higher-level care.

Patient FAQs

“Do I need bed rest?” No—once anticoagulated, gentle walking is encouraged to reduce pain and swelling.

“Will this come back?” Recurrence risk depends on whether the clot was provoked and your risk factors. Extended low-dose DOAC can reduce recurrence in selected cases.

References & Notes

Practical DVT pathway: Wells pretest probability, selective D-dimer, ultrasound strategy (repeat when appropriate), and outpatient DOAC regimens with clear duration and safety rules. Local protocols vary—follow institutional guidance. Educational only.

Educational only, not personal medical advice.