Lower Extremity Veins: Techniques and Interpretation with How To Demonstration

Deep Vein Thrombosis Examination

Now it's a examination for a deep vein thrombosis,
but we do include evaluation of the superficial veins.
We've got here the a schematic
of the great saphenous vein.
We do wanna look at the termination
of the great saphenous vein into the common femoral vein.
Here we see an a sagal orientation,
the great saphenous coming in
and emptying into the common femoral.
We see the superficial epigastric vein
in view in this image.
And what we don't wanna see is A-A-G-S-V
that looks like this, where we can see this hyper coic
material, which is thrombus extending right across the
saphenofemoral junction.
Depending on the circumstances, most
physicians would treat this as a DVT
because it does present a risk
for thromboembolism and pe.

Calf Vein Evaluation

Here is another view of the calf.
This is higher up in the calf.
We have the popliteal vein,
popliteal artery down near the bottom.
And again, if we look at the rest of the gray scale image,
we can appreciate the muscle head right here
and our gastroc anemia's artery and companion veins.
But what's important in this view is the small saphenous.
The small saphenous, of course, used
to be called the lesser saphenous or short saphenous,
and it sits way right up in a fascial sandwich.
There's a piece of fascia above it and below it,
and not much tissue next to it.
So often the saphenous, the small saphenous is hard
to distinguish and it is pretty small.
So we'd probably want
to even increase the transmit frequency in this case
and see if we can maybe decrease the number of focal zones
and move them up closer so we can optimize
that first centimeter or so of tissue depth.
If we're evaluating the small saphenous,
well image is important,
but when we talk vascular, we have
to worry about the doppler too.
And we do have to take doppler signals from
basically several major vessels.
You can do it from all the vessels.
I don't think it's really needed below the knee.
There are multiple calf veins, so if you're going
to Doppler, you really have to doppler all of them
because it's not all that helpful just
to document a doppler waveform from one of several c veins.
So we normally record spectral
doppler from the common femoral vein as well
as the popliteal vein.
Many folks also include the super, what we used
to call the superficial femoral vein.
Now the femoral vein, so it's common femoral,
femoral and popliteal.
Our kind of standard levels to document.
We record those doppler spectrums at rest
and also with augmentation maneuvers, either val Salva
or distal compression.

Bilateral Examination Requirements

And there are many reasons why we may examine patients just
for one leg symptoms with one leg.
However, we need to record
a complimentary contralateral common
femoral vein doppler signal.
If we're only doing a unilateral study,
this is a requirement by the I-C-A-V-L
and it's a requirement
because when we examine this
these common femoral vein signals bilaterally,
it'll give us a good idea
of what's going on systemically with the patient.
And we might be able
to detect things like systemic venous hypertension
or other problems.

Doppler Spectrum Analysis

So here's a doppler spectrum
where we've got our
doppler cursor in the common femoral vein.
And you notice here the angle correction is on,
and it may actually appear on in several of the images,
but it is not necessary to angle correct for venous doppler.
But you still need to get a good angle in order
to get a good doppler shift.
So you will want to try to approximate your 60 degree angle
of intonation, but here we see flow
and then no flow flow and then no flow.
And what happens is when we take a breath in
and inspire the pressure in our abdomen increases,
the pressure in the abdomen increases to a point
where it actually exceeds the pressure in
the common femoral vein.
So we basically shut down flow from the common femoral vein.
When we exhale, the pressure in our abdomen goes down,
it's now lower than the common femoral vein pressure.
So we see flow again, we should be able to see
that spontaneity
and ity in the venous doppler signal down
through the popliteal vein.
That's pretty common. You may have a little trouble
with some of the tibial veins if you are going
to do tibial vein doppler,
but you should see good spontaneous signals at least
down through the popliteal.
If not, take a look at your adjustments.
In fact, this PRF or scale is probably too high for a vein.
You might even wanna drop that down a little bit lower.

Color Doppler in Venous Exams

Well, when we talk about ultrasound,
it wouldn't be complete if we didn't discuss color.
Now, color isn't essential.
You can get through a venous exam without it,
but it certainly is helpful.
It is still considered to be complimentary and not required.
However, it can aid in the identification
of the extent of thrombus.
We can use color to help locate a vessel
of finding the companion artery and using that as a guide.
And certainly there's areas where we can't compress a vein,
so we can use the color signal
to help confirm vessel patency.
But remember, just
because you don't see color, it doesn't necessarily mean
that the vessel is thrombosed.
And just because you do see color in a vessel doesn't
necessarily mean that the vessel
is thrombus free.
That's very important.
It all depends on the settings of the equipment.
Now here we see again, a femoral vein
and superficial femoral artery kind of getting deep in view,
and we're using the superficial femoral artery as our guide
to help us follow that femoral vein
down in the calf here again,
we've got the subcutaneous tissue here,
we've got the gastroc anus muscle on top.
That's the first one. And now underneath that is the sous.
And this tributary coming out of the sous muscle
coming into the posterior tibial veins is a so vein.
We aren't getting good filling in these
posterior tibial veins.
But remember, venous flow is dynamic,
and we've got a static image here.
And these vessels are perfectly patent.
It's just a matter of timing.
We are transverse to them, so that's a little bit more
of a challenge to create an angle
so we can get good filling.
But certainly color is very beneficial when
we have things like this.
Acute non occlusive thrombus with this tail sort
of swinging in the blood flow
of this common femoral vein.
Color can help here as we see another bit
of thrombus at another patient.
In the saphenofemoral junction,
we can see while the thrombus does extend,
here's the saphenous out into the saphenofemoral junction.
We are getting flow around it
and a little bit of flow from the great saphenous,
probably from the superficial epigastric vein in fact.
And that'll help define where we see things.
Over here we've got flow filling the popliteal artery
and one tributary vessel here,
but no flow in that popliteal vein.
Here's just a series of images of the same popliteal artery
and popliteal vein.
Now here is the popliteal vein.
You can see there's echogenicity within the vessel
and a very faint amount of color filling here.
In this next view, this is the exact same location.
We still see our popliteal artery,
but we're seeing a little more color filling
in another view, even a little more color filling.
And in this view, almost not really fulfilling,
but a lot more filling than we saw in the first image.
The only thing that was changed in these images was the
color priority.
This is a setting on all ultrasound systems.
They might have different names,
but it basically tells the system how much color
to write over the gray scale.
So if your color priority is high,
you'll get a lot more color filling in
and it'll fill right in over areas
of non occlusive thrombus.
If your color priority is low, the software
of the ultrasound systems is going
to send much more power into generating the gray scale image
and not overlay very much color.
So you'll see more thrombus in less color.

Interpretation of Venous Images

Now what about interpretation of the images?
Well, normal vein should appear nice, smooth, thin wall.
You may see slight changes with respiration.
You may see some echoes,
but we usually set this up so that the lumen
of the vessels are pretty dark, pretty koic.
If we can see the valves, we may see some slight
motion within the valves with blood flow
and the valve sinuses may appear elliptical.
And here's a picture.
Actually, this is an arm vein
where we can see the valve leaflets here
and here a little bit of the insertion ridge,
this thickening here, which is part of the vessel wall.
And we have the valve open and valve closed.
And that's just during normal breathing patterns.
Sometimes though thrombus does happen behind valves.
And here's a valve that sort of stuck out,
frozen out into the lumen with lots of thrombus behind it.
And that thrombus has propagated
and extended into the lumen of the vein
and certainly represents a risk to the patient
once we find thrombus.
The other thing we need to do is characterize it
as being chronic or acute.
Some people use a third categorization of subacute.
But for the purposes of today's lecture,
we'll just talk about acute and chronic.
Here we have an artery in a vein, artery in a vein,
non compressed and compressed.
And we can see that we're not getting
compression on this vessel.
We know that it's thromboses.
When we take and document these images,
we can certainly do whatever we want.
We can include labels and arrows.
I think c small cine loops three seconds
or so are extremely valuable for the tibial level veins
that may be small and difficult to image well
with a still image.