POCUS - DVT Flashcards
Review the scans needed for a LE DVT scan.
From the groin (CFV) through the SFV to the knee (popliteal vein). Compress all the way.
Some places record a continuous view of the vein the whole way, and some places just do spot check of proximal and distal.
Make sure each area is compressible. In the CFV view, use Doppler in the longitudinal view to look for the biphasic wave. The absence of a biphasic doppler is indicative of proximal obstruction.
How many DVTs occur per year in the US?
2 million
What percent of DVTs will progress to PEs if untreated?
50%
True or false: you need to apply Doppler in a DVT study
False
Compressibility is all you technically need. Some people do Doppler for style.
What transducers can you use for the DVT study?
Usually you use the linear probe, but in obese adults you may need to use the curvilinear.
What patient position helps in this study?
Reverse Trendelenberg with leg slightly externally rotated
The femoral artery is ________ to the femoral vein.
lateral
As you begin your DVT scan from the groin, you will see two vessels: the CFA and the CFV. As you go down, you notice that one of the vessels bifurcates. Which one was it?
The CFA
As you move your probe inferiorly, the CFA bifurcates into the superficial FA and the deep FA.
Below that you will see the greater saphenous vein break off of the CFV.
The ___________ is lateral to the CFA.
femoral nerve
As you move your probe inferiorly, the CFV splits into the ______________.
SFV and the DFV (these parallel their arterial counterparts)
Venous duplication is common at the _________ level, so be sure to do a quick scan for other veins (you don’t want to miss a clot in the duplicated vein).
SFV
When the CFV splits into the SFV and DFV, the veins are __________ (internal or external) to their arterial counterparts.
internal
So the SFV is deep to the SFA and the DFV is superficial to the DFA.
Near the ____________ it is normal for the SFV to not be compressible with transducer probe pressure alone. You need to do manual pressure with your other hand from the posterior side in addition to anterior probe pressure.
adductor canal
When you are scanning the popliteal area, have the patient in what position?
Supine with knee flexed and hips slightly externally rotated
You scan the popliteal vein and find it just above the PA. When you slide your probe inferiorly you see two smaller triplets of vessels superficial to the PV and PA. What are these?
The gastrocnemius vessels
The gastroc arteries are in the middles of the triplets with a pair of veins on either side
You should find the __________ branch off of the PV because if there is a clot at the junction then you need to treat.
lesser saphenous vein
If you feel like you’re pressing hard enough on the veins but aren’t sure, what can you look for to know?
If you see tenting of the arteries (evidence that it’s being squished), then the veins should be compressing with that level of force.
The most common spot for DVTs is the ____________
popliteal vein
Followed by SFV, DFV, and CFV.
What test can diagnose DVTs proximal to the CFV?
Put doppler on the CFV. It should have a biphasic, undulating appearance. If the doppler wave is flat, this is suggestive of proximal occlusion.
When you are evaluating for clot, be sure to fully ______________.
compress
Partial compressibility is not diagnostic.
Although differentiating an acute clot from a chronic clot is not always possible, what are some features that suggest an acute clot and a chronic clot?
Acute:
- Mobile edge
Chronic:
- Web-like structure with canalization
Trace the paths of the LSV and GSV.
LSV originates on the dorsum of the foot and tracks laterally across the ankle then posteriorly up the calf to join the PV.
GSV originates superior to the medial malleolus then tracks medially up the leg to join the CFV.
True or false: positive color flow rules out clot.
False
A non-obstructive clot can have color flow.
Even though you only need to record the CFV, SFV, and PV, you should check for continuous compressibility. Why?
You could miss a focal thrombus if you did not check for continuous compressibility.
Venous duplication at the SFV or PV occurs in what fraction of people?
1/3
Superficial thrombosis within ____ cm of the saphenofemoral junction warrants treatment.
5
