Duplex Imaging

reasons to use duplex

presence of thrombus

relative risk of thrombus traveling to lungs (PE)

competence of valves

deep veins

main conduit for blood returning to heart (freeway of the venous system)

paired with an artery

higher risk for PE due to squeezing action of surrounding muscles

thrombus in deep system usually larger than superficial

*DO NOT AUGMENT WITH DVT

superficial veins

plays large role in regulating body temperature

less likely to cause life threatening PE

but greater potential for embolus if the thrombus is near a junction that connects to the deep system

venous thromboembolism & post thromb. syndrome

consists of venous thrombosis and PE

PE is a complication of DVT

post thrombotic syndrome is also a concerns (chronic condition carries significant morbidity)

virchow’s triad

primary mechanism for formation of venous thrombosis

1) venous stasis

2) vessel wall injury

3) hypercoagulable state

Vichow’s triad in depth

venous stasis: increases exposure to clotting factors

vessel wall injury: affects body’s normal thrombolytic system, result of catheter/injury

hypercoagulability: associated w/various diseases, genetic factors

where does venous thrombus commonly begin?

around valve cusps in the calf

areas of slower blood flow, stagnation leads to coagulation

signs & symptoms

many are asymptomatic

pain, swelling, venous distention, discoloration, palpable cord

pulmonary embolism (PE)

a blood clot in the lungs that starts in the legs or pelvis and travels to the lungs

biggest risk to a DVT

2 clinical markers for DVT

Well’s criteria: DVT probability scoring. score > 3 means high risk of DVT

D-dimer: lab test of breakdown of fibrin which will be elevated in DVT

*both of these tests have poor sensitivity & specificity so US is most important tool

patient positioning

reversed Trendelenburg position

common duplications

femoral vein and popliteal can have duplications

soleal sinus veins

common site of thrombus formation since its a major storage area for blood & is stagnant

iliac veins & when we scan them

phasic flow at CFV means we don’t scan iliac

continuous flow is sign of obstruction at iliac so we scan it

external iliac is continuation of CFV

internal iliac joins external to form common iliac

common iliacs join on each side to form IVC

wave forms

phasicity is normal

continous is not normal

pulsatile is not normal

acute thrombus

newly formed clot >14 days

lightly echogenic/hypoechoic

poorly attached to vessel wall

spongy texture

dilated vein

can be invisible on US

chronic thrombus

clot present <2 weeks

brightly echogenic/hyperechouc

well attached to vessel walls

rigid texture

contract vein

large collaterals

becomes more echogenic with age

*chronically thrombosed veins can be hard to differ. from surrounding tissue (may appear as thin scar w/in lumen (residual string))

what does continuous flow mean

proximal obstruction

abnormal color doppler

alternating antegrade & retrograde flow is abnormal

usually results in valve damage (seen in venous valve insufficiency)

May-Thurner Syndrome

left common iliac compression by the right common iliac artery

mostly in women

Phlegmasia Alba Dolens

extensive iliofemoral DVT causing swelling & other symptoms

also called milk leg or white leg

Phlegmasia Cerulea Dolens

more extensive than PAD

even more massive swelling & symptoms

venous outflow is completely obstructed

other dx if not DVT

cyst, hematomas, edema, abscess, lymph nodes, tumors, aneurysms, etc.

baker’s cyst

AKA popliteal cyst

fluid-filled distended, synovial-lined lesions located at or below the joint line

not a true cyst as it’s a communication b/w the joint capsule

DVT treatment

primary treatment is anticoagulation

elastic stockings

surgical thrombectomy