DEEP VENOUS ULTRASOUNDPetra Duran-Gehring, M.D.

University of Florida-Jacksonville

Department of Emergency Medicine

Objectives

Describe the indications and limitations of focused ultrasound for the detection of deep venous thrombosis

Understand the standard ultrasound protocol when performing a focused exam

Define the relevant local anatomy Develop an understanding of doppler physics

and instrumentation Recognize the relevant focused findings and

pitfalls when evaluation for deep vein thrombosis

Deep Venous Thromboembolism

Incidence in U.S.: 1 in 1000 people/year 10% of proximal DVTs will lead to PE 50% of untreated proximal DVTs will lead

to PE within 3 months >80% of PEs due to DVTs

DVT Risk Factors

Recent Trauma Recent Surgery Immobility Cancer Estrogen

Pregnancy OCPs

Prior DVT/PE

Family history of hypercoagulabity Protein C or S

deficiency Factor V lieden or

Antithrombin III deficiency

Antiphospholipin or anticardiolipin antibody

Homocysteine Lupus anticoagulant

Physical Exam

Unilateral leg swelling Tenderness to palpation Redness Warmth Palpable cords- rare Homann’s sign- rare Pratt’s sign

Poor sensitivity and Specificity

Lower Extremity DVT

Popliteal 10%

Popliteal + Superficial Femoral 42%

Popliteal + Superficial Femoral + Common Femoral 5%

All proximal vessels 35%

DVT Diagnostics

Contrast Venography Former gold standard Time consuming IV dye exposure

Plethysmography CT MRI Ultrasound

Low cost Portable Non-invasive

Ultrasound Protocols

Duplex Comprehensive Color flow Doppler Time consuming (about 45 mins)

Limited Compression Focused technique Bedside exam Look for clot only in

Common femoral vein Popliteal vein

Limited Compression Ultrasound

Focus on proximal veins Thrombi distal to popliteal rarely

embolize Distal thrombi may propagate to popliteal Therefore, if DVT suspected, must rescan in

3-5 days Clot is identified by the lack of normal

compressibility of the vein Proven to be as accurate as Duplex US

and better than plethysmography in finding proximal clots

Lower Extremity Venous Anatomy

Common Femoral Superficial

(saphenous) Deep

Deep Femoral (Profunda)

Superficial Femoral Popliteal

Anterior Tibial Peroneal Posterior Tibial

Common Femoral Deep

Femoral

Superficial Femoral

Popliteal

Common Femoral Anatomy

Common Femoral Vein

Femoral Artery

Femoral Junction Anatomy

Common Femoral Vein

Femoral Artery

Saphenous Vein

Femoral Bifurcation Anatomy

Common Femoral Vein Femor

al Artery

Profunda Femoris

Superficial Femoral Anatomy

Superficial Femoral Vein

Femoral Artery

Popliteal Anatomy

Popliteal Vein

Popliteal Artery

Scanning Technique

Linear array probe 6-10 mHz Medium footprint If pt is obese, may need to use a lower

frequency sector probe Positioning

Reverse trendelenberg Semi-sitting with hips in 30 degrees flexion

Ultrasonic DVT Findings

Non-compressibility Echogenic material with lumen Decreased blood flow

Despite augmentation

Compression

Compress vein using transducer

Complete apposition of the vein walls needed to rule out DVT

If compression is not achieved with pressure sufficient to deform adjacent artery, thrombus present

Common Femoral

Pt placed in supine position

Leg externally rotated

Probe indicator to pt’s right

Femoral Vein

Place probe in inguinal crease

Use color flow doppler to distinguish vessels

Scan from CFV through the SFV

Compress as you go

Femoral Vein DVT

Popliteal

Position Prone Decubitus Seated on edge of

gurney Knee bent to

increase venous filling

Reverse trendelenburg

Probe indicator to pt’s right

Popliteal

Place probe 10-12 cm above bend in knee

Use color flow doppler to distinguish vessels

Scan through to the trifurcation of the popliteal

Compress as you go

Popliteal Vein DVT

Scan Protocol

Begin by palpating femoral pulse Place transducer over inguinal ligament with

probe indicator to pt’s right Scan through the common femoral to the

bifurcation (about 10 cm) Move to posterior knee bend Scan through popliteal to the trifurcation Take clips to illustrate compressibility May need to image the contralateral side if

results questionable

Pearls

Augmentation of flow by compressing the calf can help distinguish the vein from artery

Optimize gain to best see the vascular system

If case equivocal, scan other side and compare

May scan through the superficial femoral vein is clinical suspicion is high

Questions???