Cardiovascular · Topic 43 of 48

Deep Vein Thrombosis

Cardiovascular · venous thromboembolism

Deep Vein Thrombosis

Score it, test it, treat it: Wells, then D-dimer or duplex, then a DOAC for at least 3 months — longer when unprovoked.

Key numbers

Wells score sets the pretest probabilityWells ≥ 3 = high

Anticoagulate at least 3 months≥ 3 months

Warfarin: overlap heparin until INR 2–3INR 2.0–3.0

01 · DoLow probability: negative D-dimer excludes DVT

In a patient with low pretest probability, a negative D-dimer excludes DVT without imaging; D-dimer is sensitive (about 96%) but nonspecific (about 37%), so a positive result only means more testing.

02 · GiveA DOAC is first-line treatment

First-line DOACs: apixaban 10 mg twice daily for 7 days, then 5 mg twice daily, or rivaroxaban 15 mg twice daily for 21 days, then 20 mg daily with food — no heparin lead-in.

03 · The ruleAnticoagulate at least 3 months

Primary treatment lasts 3–6 months. Stop after that if the DVT was provoked by a transient factor; continue indefinitely if it was unprovoked or the risk factor persists, unless bleeding risk is high.

Diagnosis & monitoring

Work-up

Wells score sets the pretest probability must knowEstimate pretest probability with the Wells score before testing — 1 point each for findings and risk factors, minus 2 if another diagnosis is as likely: ≥ 3 high, 1–2 moderate, ≤ 0 low.

Do right now

In this order

First moves

Wells score sets the pretest probabilityWells ≥ 3 = high

→

Low probability: negative D-dimer excludes DVT

→

Compression duplex ultrasound confirms DVT

→

A DOAC is first-line treatment

Why each step

Wells score sets the pretest probabilityEstimate pretest probability with the Wells score before testing — 1 point each for findings and risk factors, minus 2 if another diagnosis is as likely: ≥ 3 high, 1–2 moderate, ≤ 0 low.

Low probability: negative D-dimer excludes DVTIn a patient with low pretest probability, a negative D-dimer excludes DVT without imaging; D-dimer is sensitive (about 96%) but nonspecific (about 37%), so a positive result only means more testing.

Compression duplex ultrasound confirms DVTHigh pretest probability or a positive D-dimer goes to compression duplex ultrasound — a noncompressible vein is diagnostic; it is about 90% sensitive and 98% specific for lower-extremity DVT.

A DOAC is first-line treatmentFirst-line DOACs: apixaban 10 mg twice daily for 7 days, then 5 mg twice daily, or rivaroxaban 15 mg twice daily for 21 days, then 20 mg daily with food — no heparin lead-in.

Management

Orders

Dabigatran and edoxaban need 5 days of heparinDabigatran 150 mg twice daily or edoxaban 60 mg daily start only after 5 days of LMWH or UFH; edoxaban drops to 30 mg for CrCl 15–50 or weight ≤ 60 kg.

Warfarin: overlap heparin until INR 2–3If warfarin is used, start it within 24 hours alongside LMWH or UFH and overlap for at least 5 days until the INR is in the 2.0–3.0 target range.

LMWH for pregnancy and breakthrough on warfarinLMWH (enoxaparin 1 mg/kg every 12 h or 1.5 mg/kg daily) is first line in pregnancy and for recurrence on therapeutic warfarin; for cancer-associated DVT, apixaban, edoxaban or rivaroxaban are now preferred over LMWH.

UFH infusion when CrCl is under 30IV unfractionated heparin (aPTT 1.5–2.5 times control) suits hospitalized patients and those with CrCl 10–30 mL/min because it is not renally cleared; protamine reverses it more completely than LMWH.

Treat uncomplicated DVT at homeMost patients with uncomplicated DVT are treated as outpatients; admit when severe pain needs parenteral analgesia, other illness makes discharge unsafe, or the patient cannot adhere to therapy.

Isolated calf DVT: serial ultrasound or anticoagulateIsolated distal (calf) DVT without severe symptoms can be followed with serial ultrasound instead of anticoagulation, treating only if the thrombus extends toward the proximal veins.

Extended phase: reduced-dose apixaban or rivaroxabanFor indefinite therapy after 6–12 months, apixaban 2.5 mg twice daily or rivaroxaban 10 mg daily are acceptable; aspirin is inferior to anticoagulation for secondary prevention.

Red flags & don'ts

Avoid harm

Antiphospholipid syndrome: warfarin, not a DOAC avoidUse warfarin rather than a DOAC for DVT in antiphospholipid syndrome; DOACs are also avoided in severe renal impairment (apixaban, rivaroxaban and dabigatran for CrCl < 30) and moderate-to-severe liver disease.

IVC filter only if anticoagulation is contraindicated avoidPlace a (preferably retrievable) IVC filter only for lower-extremity DVT when anticoagulation is contraindicated; filters do not lower mortality, increase later DVT, and are not added to anticoagulation routinely.

Phlegmasia cerulea dolens: limb-threatening iliofemoral DVT complicationMassive iliofemoral DVT with a swollen, painful, cyanotic leg (phlegmasia cerulea dolens) threatens venous gangrene: give catheter-directed thrombolysis, with thrombectomy or fasciotomy if it fails.

The rules

Know these

No routine thrombolysis for proximal DVTAnticoagulation alone is preferred over thrombolysis for proximal DVT; catheter-directed lysis is reserved for limb threat or selected patients under 60 with extensive iliofemoral DVT and low bleeding risk.

Thrombophilia testing only in selected patientsMost patients with VTE need no thrombophilia work-up. ASH 2023 suggests testing after VTE provoked by pregnancy, estrogen or a nonsurgical transient factor, or at an unusual site (cerebral, splanchnic) when stopping anticoagulation is being considered.

Provoked or unprovoked DVT?

Commonly confused

Examples	Surgery, trauma, immobilization
Primary treatment	3–6 months
After primary treatment	Stop anticoagulation
Recurrence risk	Lowest

More detail

Reference

Show 8 reference facts

Early ambulation is safe and encouraged after starting anticoagulation; it does not increase embolization and may reduce post-thrombotic syndrome. Short NSAID courses only, avoiding prolonged NSAIDs or aspirin.

Routine compression stockings to prevent post-thrombotic syndrome are not recommended, though they can relieve swelling and pain.

Recurrence risk is lowest after DVT provoked by surgery, trauma or temporary immobility and highest with cancer, unprovoked DVT or residual thrombus.

An age-adjusted D-dimer cutoff (age × 10 ng/mL) is used for patients over 50, because D-dimer rises with age, pregnancy, cancer, surgery, trauma and inflammation.

About half of patients with DVT have occult pulmonary emboli, and post-thrombotic syndrome affects up to 50% of patients after DVT.

Upper-extremity DVT (under 5% of cases) is usually catheter- or device-related; effort thrombosis of the subclavian vein (Paget-Schroetter) suggests thoracic outlet compression.

Homans sign is neither sensitive nor specific; whole-leg swelling, calf asymmetry over 3 cm, pitting edema and collateral superficial veins are the more specific findings.

Stop concomitant aspirin during anticoagulation for VTE in patients with stable cardiovascular disease, to limit bleeding.

Pearl

Low probability gets a D-dimer; high probability or a positive D-dimer goes to duplex ultrasound.

Sources · Merck Manual Professional — Deep Venous Thrombosis (DVT) · Merck Manual Professional — Medications for Deep Venous Thrombosis · Ortel TL et al. American Society of Hematology 2020 guidelines for management of VTE: treatment of DVT and PE. Blood Adv 2020;4(19):4693–4738 · MDCalc — Wells' Criteria for DVT · Merck Manual Professional — Chronic Venous Insufficiency and Post-Thrombotic Syndrome · Stevens SM et al. Antithrombotic Therapy for VTE Disease: Second Update of the CHEST Guideline and Expert Panel Report. Chest 2021;160(6):e545–e608 · Middeldorp S et al. American Society of Hematology 2023 guidelines for management of VTE: thrombophilia testing. Blood Adv 2023;7(22):7101–7138 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).