US review March 9, 2011

Rule out DVT

If the vein completely compresses there is no underlying clot.

no clot clot

Linear Array Probe (5-10 mHz)

Patient reclines at 45o Hip externally rotated

Note: SFV – “superficial” femoral vein is a deep vein!

Just 2 key areas to compress

Our protocol: 4 compression clips CF-saph bifurcation pop “trifurcation”

A normal exam:

Clip #1 CF-saph

CFV – G. Saphenous Junction

Clip #2 bifurcation

Bifurcation: SFV and DFV

Clip #3 pop

Pop V

Clip #4 “trifurcation”

“trifurcation”: pop divides

Some clots:

DVT in CFV

Clip: partially occlusive DVT

movie: mobile DVT

movie: DVT in CFV

Movie: DVT in pop

Chronic DVTs look different

Chronic DVT shrunken fibrotic (hyperechoic) collaterals recanalized

clip: lymph node

The exam is simple!

Stuff you don’t have to know:

You can skip: the mid-thigh the calf Doppler

mid-thigh: SFV

Calf veins: OK to skip

Calf DVTs - Unreliable to diagnose: < 70% sensitivity - Unclear significance: 75% resolve without treatment

But what if you find a calf DVT? Plan A: anticoagulate Plan B: ASA only. Monitor for extension (Not all calf veins are equally important)

Clip: calf veins

Is Doppler needed? No. Compression is sufficient. Color can sometimes help identify vessels. Doppler can give false normals: eg non-occlusive DVT has normal augmentation.

Doppler flow info: Augmentation: - squeeze the calf and blood rushes past the probe - implies no obstruction between calf and probe Respiratory phasicity: - flow stops on inhale, goes on exhale - implies no obstruction up in pelvis

Venous flow (note respirations)

phasic flow and augmentation

What is “duplex”? 2 modalities together: U/S + Doppler

Quiz!

A C B

A C D B

A B

Where on the leg are we?

The End