Deep Vein Thrombosis

KEY FACTS

Terminology

  • Deep vein thrombosis (DVT), pulmonary embolism (PE), venous thromboembolism (VTE)

  • Deep vein thrombosis (DVT): Thrombus forms within deep venous system, typically in lower limbs

Imaging

  • Complete compression ensures no thrombus is present

  • Thrombus becomes more echogenic as it ages, as well as more linear and cord-like as chronic process

  • Chronic sequelae of thrombus can cause scarring, decrease in vessel lumen, and chronic reflux and stasis

  • Loss of respiratory phasicity is suggestive of obstruction closer to heart

  • Augmentation (↑ in flow velocity with distal compression)

    • Poor augmentation suggests downstream obstruction

  • Acute thrombosis (~ 14 days)

    • Thrombus hypoechoic, may distend vein if occlusive

    • May see free-floating thrombus

    • Collateralization: Tortuous and braided collateral veins, usually smaller than normal vein

    • Associated slow flow may be seen as visible mobile echoes moving back and forth in real time/cine clip

  • Subacute thrombosis (~ 2 weeks to 6 months)

    • Thrombus becomes more echogenic, variable

    • Luminal flow may be restored or vein may stay occluded

    • Collateral venous channel continues to develop

  • Chronic phase (≥ 6 months)

    • Postthrombotic scarring forms

    • Scarred veins are thick-walled with reduced diameter

    • Plaque-like fibrous scars, synechiae form along vein periphery and may occasionally calcify

    • Synechiae: Formed from unlysed thrombus that is attached to one side of vein wall and gradually transformed into fibrous band

    • Fibrous cord: In nonrecannalized vein, vein reduced to echogenic cord smaller than normal vein

    • Valve abnormalities

Clinical Issues

  • Most are treated with anticoagulation or IVC filter, with thrombolysis having role in severe situations

  • Important to assess if there is any history of prothrombotic risk (congenital or acquired)

Scanning Tips

  • Perivascular edema may mimic nonocclusive thrombus especially on compression views; however, look for smooth echogenic intima of vein, which is often more prominent with perivascular edema

  • Femoral vein (FV) and popliteal veins are often duplicated

  • If 9 linear transducer is not able to penetrate to level of vein due to patient body habitus or limb swelling, try curvilinear probe

  • Refractive edge shadow from fascial planes may obscure distal FV; slightly anterior/medial approach using vastus medialis muscle as acoustic window may help visualization

  • Calcified arteries may obscure visualization of adjacent deep vein and create pseudo filling defect on color Doppler images; avoid using adjacent artery as acoustic window in these patients

Nov 10, 2024 | Posted by in ULTRASONOGRAPHY | Comments Off on Deep Vein Thrombosis

Full access? Get Clinical Tree

Get Clinical Tree app for offline access