Ultrasound Scanning for Deep Venous Thrombosis - SD

Introduction to Ultrasound for Deep Venous Thrombosis

Hi, I am Deborah Rubins.

I'm from the University of Rochester,
and the topic of my talk is basically ultrasound
for the diagnosis of deep venous thrombosis.

We'll be reviewing technique
and also findings in DVT.

Today we're gonna be talking about ultrasound scanning
for deep venous thrombosis,
and we'll be learning the protocols
to perform successful upper
and lower extremity venous examinations.

We'll become familiar with the roles
of compression ultrasound color
and spectral doppler as we make the diagnosis of DBT.

And lastly, we'll be looking at some
of the main pitfalls in venous extremity ultrasound.

Background on Venous Thromboembolism

To begin with,
venous thromboembolism is a very common problem.

It affects 70 out of a hundred thousand patients annually.

It is associated with
pulmonary embolism 90% of the time.

And that's in patients who do have DBT.

Pe as you know, causes many deaths per year.

And currently
for extremity DVT ultrasound testing is the primary
diagnostic method.

You can see here a patient
who has obvious pulmonary emboli in the pulmonary arteries.

Cancer patients are a special high risk population
because the incidence of ven thromboembolic disease is
as much as double the general population.

And it even increases in patients with metastatic disease,
especially in patients who are high risk,
including patients with GI malignancies.

Sometimes it's
because these patients are hypercoagulable
and then often it's
because patients have catheters which incite thromboembolic
disease on the catheter.

Here you can see a patient with a catheter in place
and you can see the clot forming along the
margins of the catheter.

And then this extends into the axillary vein.

Clinical Importance of DVT

Clinically, DBT is important
because patients present with pain
and swelling of the affected limb.

And of course, as we all already said,
there is an increased risk of pulmonary embolism.

Of patients with pulmonary embolism,
70% may have an asymptomatic deep venous thrombus.

If the thrombus is from a lower extremity
and very small, usually that embolus is asymptomatic.

Only five patients actually
with symptomatic DVT will have isolated cath thrombosis,
but of these approximately 30% will extend into the thigh
or popliteal veins.

So even c thrombosis are important to make the diagnosis
again, in addition
to acute D-V-T-D-V-T can be a chronic problem,
with recurrent disease in 20% of patients,
often in the same leg, sometimes in the other leg.

And again, patients who go on to have pulmonary embolism
after having had a DVT.

In addition, patients who have had a primary event
of deep venous thrombosis may develop post litic syndrome,
which is valve damage
and then development of chronic pain and swelling.

And the incidence of this is estimated to be as much
as 29% at eight years after the initial event.

Anatomy of Deep Veins

So to make the diagnosis of deep vein thrombosis,
first we need to remember our anatomy.

So which lower leg vessels actually can harbor a
deep vein thrombosis.

Well, basically the deep veins are anything
that go through a muscle.

So the iliac vein, the common femoral vein,
profunda femoral vein,
and the paired deep calf veins are certainly qualifiers.

In addition, the muscular veins, including the gastroc anus
and soleus plus unnamed tributaries that go
through the muscles are also deep veins.

And in addition, the greater saphenous vein,
which is actually a superficial vein,
is considered a harboring clot, which can be considered
as significant as deep venous thrombosis in the
distal two centimeters.

And that's because this clot has the same propensity
to get into the deep venous system
and go to the lungs
as something which actually originates
in the deep venous system.

So clot in this location is treated
as deep venous thrombosis.

One more thing about normal anatomy.

You can remember from medical school
or from any other anatomic course where you've taken
that the arteries and veins are labeled as the superficial
and deep femoral artery and vein.

However, the superficial femoral artery
and vein, which is basically the main vein
that's draining the leg,
is actually now called in our nomenclature,
the femoral vein, because some clinicians,
if you use its anatomic name, we'll ignore the fact
that there's clot in this location.

And believe this vessel is not really a deep vein.

So the calf veins,
the way we look at those is we wanna scan the paired veins
with graded compression
and identify the adjacent artery as needed.

The tibial perineal trunk,
this is just anatomic information,
is actually the confluence of the perineal
and posterior tibial veins.

It's this little portion right in here,
which occurs
before the confluence with the anterior tibial veins,
which occurs just below the popliteal vein.

We wanna scan the caffeines in their entirety in addition
to scanning the vessels above the knee.

And just to show you that you can see these caffeines
here is the artery.

Here are the paired posterior tibial veins,
which you can see coapting completely
as we do graded compression on this little area
of the popliteal.

The muscular caffeines, as I said, are also deep veins.

Remember the gastroc anemia veins
will be in the gastrocnemius muscle.

They often can be identified
by an accompanying artery within the muscle,
and they will enter the popliteal vein.

You can see here on the sagittal image,
this is the more superficial muscle group here.

The so sinuses are in the so muscle
and they're in the deep vessels.

The deep muscles which are adjacent to the tibia.

There's no paired artery here,
and they will empty into either the posterior tibial
or peroneal veins.

These are fairly small.

There are some normal variants to be aware of.

The femoral and popliteal veins are commonly duplicated,
at least 20% femoral duplication
and 30% popliteal duplication in normal populations.

It's important to recognize this
because in patients who have duplicated femoral veins,
the incidence of DBT is much higher rising to even 38%.

You can even get triplicated segments, and as we said
before, unnamed muscular branches may occur.

So in this image here, you can see the paired
femoral vein in its mid portion notice it's combined up here
approximately, and actually will merge down here distally.

Why is this important?

Because you wanna be sure to look for these duplications.

Here's a patient with an artery, a vein,
which is mostly collapsed,
and over here a vein which has thrombus within it
and is not collapsing, as I said,
a triplicated segment can occur.

Here's just an example of a patient
with a triplicated segment.

You can take spectral tracings from all three
and show that yes, these are all venous wave forms.

But easier is the compression examination over here
where you can just look at the vein, the vein, the vein.

Here's the adjacent artery.

When you compress, all the venous structures should
disappear and only the arterial structure remains.

Compression Ultrasound Technique

So the compression technique is the
mainstay of our diagnosis.

You wanna use a high frequency linear array transducer.

This is a gray scale examination,
so you want very good image quality with your gray scale.

You compress every centimeter from the common femoral
vein to the popliteal trifurcation
or to the tibial perineal trunk
and the anterior tibial vein.

And then you'll continue in the calf
through all the paired veins as well.

And the mainstay is
that the vein walls should coapt completely
if they don't be suspicious that you have a DBT.

Here's an example of the common femoral vein.

You can see it here collapsing completely.

The artery, which is next to it, does not collapse.

And you can see the adjacent arterial pulsation.

As the vein collapses.

You should still be able to see the artery right there.

One pearl here is
that if you're compressing in the thigh,
sometimes the bone gets in the way.

So you can use one hand behind the medial thigh
and help compress the femoral vein in the adductor canal.

You wanna scan the groin
and the proximal thigh from the anterior aspect.

In the mid thigh, you'll go medially to be on
that femoral vein and in the distal thigh.

As the vein dives deeply, you may need to go posteriorly
and you certainly need to go posteriorly behind the leg
to get to the popliteal vein.

If you want the veins to be distended, it's good
to have the patient's head elevated.

And if you need to have the patient dangle his
or her legs over the side of the bed,
and that will help you distend the C
veins to better see them.

So we tend to use just compression still images.

It's a quick, easy way to record.

The left side of the image is the distended vessels.

And as we compress, you can see that the veins go away.

This is just a little bit of muscle here,
and the artery is left behind, again, vein
and artery, artery left behind.

And that goes all the way through down to the popliteal.

So the diagnosis of A DBT is made
by a non-compressible segment.

In gray scale, the clot will expand the lumen,
and also if you're using color,
it will displace the flow in the lumen.

So here we see a patient in long axis.

Here's the popliteal vein with a thrombus within it.

And you can see again on transverse,
the popliteal vein is not collapsing.

It's important to do the compression
and not just rely on gray scale,
because here you can see that there's a patient
with an koic, acute thrombus in the common femoral vein.

Very difficult to see just on the gray scale alone.

So here's a quiz case for you.

Is this a deep venous thrombosis
or a superficial vein thrombus?

You can see here is a vessel and it's standard.

And here you can see the clot within it on the gray scale.

And when the compression is performed,
you can see there's an area here that is not compressing.

And you can see here that the sonographer labeled that this
as a superficial vein,
but it's actually not a superficial vein,
it's a muscular vein because it's traveling in the muscle.

Here is the subcutaneous tissue up here.

A superficial vein would be in this layer of the tissue.

So this is a muscular vein, and this was a DVT.

And this patient has pulmonary emboli. So an important clot.

Color Doppler in Venous Ultrasound

When do we use color?

Well, first of all,
the color doppler technique I think is useful
to find some deep compressed veins in patients
who have a lot of edema or swelling.

You can help by squeezing the calf
or using a Val Valsalva release to increase the flow
and that will help you see the vessels with color.

This is not helpful diagnostically in
terms of augmentation.

If you for some reason cannot compress the patient,
for example, a patient who has severe contractures
or has a great deal of pain
or can't tolerate compression,
you can actually use color doppler alone,
especially above the knee.

And that is basically for proximal DBT between the thigh
and between the groin and the knee in the thigh vessels.

So here's an example of a patient who had contractures.

You can see here's color flow in the common femoral vein
and in the femoral vein here, this is an old scan,
so we were still using the wrong terminology here,
but this is a patient where we could not get in
to actually compress with gray scale.

This patient is post gastrectomy
and we see calf clot detection
with both gray scale and color.

Sometimes it's a little hard
to see things with gray scale.

If I didn't have arrows here, it might be hard to see
that there are two vessels here.

They both compress but down deeper.

You can see here there's actually one
that's not compressing.

And if you wanna look on long axis, that can be useful
to show you the length and extent of the thrombus.

Color is helpful sometimes to show the proximal extent
of clots, especially when they're in the groin and above,
because you cannot always compress the common femoral vein
once it dives deep into the pelvis
to become the external iliac vein.

So this is a patient who has a common femoral vein clot.

And as we go up above it again, we're able to see
that it does not extend into the external iliac.

The vessel is patent above this clot.

So question here, another quiz case for you.

Is this normal or abnormal?

This is the femoral vein and it's upper portion
and the mid portion looks fine.

Here it is inferiorly
and we can see on here again, left hand side two vessels,
everything compresses.

And of course, does this look normal? The answer is yes.

But we haven't completed our exam
because this is a patient with a profunda femoral vein clot.

So here we have a large clot in the profunda femoral vein,
and this is a deep venous thrombosis
and you can see it right here sitting nicely partially occlusive
and ready to head north if it wants to.

Color Doppler Pitfalls

Some color Doppler pitfalls.

If you rely on color doppler alone without compression,
you can actually write over the thrombus if the color
settings are too high,
or if you have a partial volume effect.

If you use the color only of the long axis, you may miss
where the clot is.

So you wanna make sure you use color in the transverse plane
as well as in long axis,
especially if you're using color alone.

Again, evaluation
of the proximal extent into the iliacs may be difficult if
patients are very large or have a lot of gas
and you have a poor acoustic window.

So just an example, again, here's a pitfall.

A patient who has color bleeding over the
posterior aspect of the vessel.

And this is the typical place where color bleeding occurs.

So to make sure your settings are okay,
you wanna always check the posterior margin
because you can see here anteriorly the color is fine,
but posteriorly there's too much color.

So this color gain is set too high.

Here's a patient where everything looks okay.

And what's the pitfall here?

Well, we move just a little bit to the side
and all of a sudden,
there's a big thrombus sitting in here.

So if you are not using compression, you wanna be sure
not just to use long axis color in one part of the vessel,
you have to sweep from side to side
and especially you wanna go transverse
because you can see here is a very small thrombus
in terms of its dimensions, it's sitting only in the middle
and posteriorly on the vessel.

And if you image through this part in long axis
or this part in long axis, you'll miss this entirely.

Here is a patient where we had an initial exam.

We can see this looks like there might be a little bit too
much color here, but in addition,
the compression exam was probably not done as
critically as it should have been.

And this was missed on color as well as on compression.

And we brought the patient back
and found this clot just six hours later.

And you can see this is a very small length clot,
but it's a very significant clot, again,
sitting just at the junction
and hanging loose in the middle of the lumen ready
to go up to the lungs.

So this is the pitfall of a small thrombus.

You wanna be sure on your compression exam really
to be meticulous about going every centimeter
so you don't miss this.

And again, use that transverse image on color
to make sure that you're not missing the clot here.

You can see this clot here on the adjacent CT looking
the same as it does on the ultrasound,
but again, it's only a centimeter and a half long.

Spectral Doppler in Venous Ultrasound

When do we use spectral doppler?

Well, the spectral doppler waveform is very useful to look
for abnormalities above
where you can actually directly compress.

So a monotonous ipsilateral waveform will indicate more
proximal disease either within the vessel, intrinsic
or extrinsic adjacent to the vessel.

And if you have a bilateral abnormality,
that means either you've got problems in both iliac veins
or in the IVC or around those vessels.

So just some examples here on the normal common femoral
spectral wave form here on the right
and on the left, you can see good puls here returning all
the way back to baseline, even if it's only halfway back
to baseline, that's certainly good
enough to be called normal.

An abnormal waveform is something that's monotonous
that goes less than halfway back to the baseline
as this patient does.

And there is one common physiologic entity which can cause this.

In this patient, we did something,
we changed the position.

You can see here it says decubitus decubitus,
right common femoral vein.

And you can see that the puls fity
and the variability came back.

And here with the Val Salva, you can see a good obstruction, if you will, of the waveform
as the patient holds her breath.

And this is a patient who was pregnant.

So the weight of the uterus basically was compressing
her IVC as well as her iliac vessels.

And so when we turn her off of her IVC,
onto her left side, we can restore the flow in her veins.

So how significant is this as a clinical problem?

Well, when we did our review of our patients, we found
that out of almost 3000 patients,
about 124 did have a monophasic waveform
and we had correlation with CT or MR
and a good majority of those.

We found about 40%
of them actually did have DVT involving the iliac veins.

So a high incidence of that,
about 20% had extrinsic compression,
some had intrinsic narrowing,
and then unfortunately in a fair percentage,
there was really no explanation
for why we had a monophasic waveform.

But just some examples of patients
who have abnormalities with their monophasic waveform.

Here's a patient with a unilateral abnormal right side.

You can see the ity is normal on the left
returning to the baseline.

And on this patient when we went, you wanted to try to see
as high as you can.

And here you can see on the right side,
the transverse iliac, you can see that you cannot see
a waveform,
you can't see any color in here in this vein.

Whereas on the left side you could see color.

And when we turn longitudinally on the right side,
there is a large thrombus sitting higher than we would
normally have performed our ultrasound examination had we
not looked for this monophasic waveform,

bilateral abnormalities, here's a patient
with monophasic waveforms bilaterally.

You notice that these vessels will still compress.

So it's the waveform that's going to clue you in
to the fact that there's something happening up above.

And in this patient it had to be
to be retroperitoneal adenopathy in a patient
with uterine carcinoma.

Unilateral monophasic waveform, again,
can be from extrinsic compression
as in this patient right side is normal,
left side, very abnormal.

You can see the vessel here normal on the
right on the left side.

This left iliac vein is gonna be compressed
by this necrotic adenopathy from this patient
with bladder cancer.

So monotheistic waveforms are very significant.

They're a reliable indicator of proximal obstruction.

40% of iliac thrombosis was the cause in our series,
and that does have the same clinical significance
for pulmonary embolism and post tic syndrome as a thigh DVT.

So it's very important to look for these.

And if you don't have this in your protocol
for your examination, I encourage you to add it in.

The incidence
of iliac vein is higher than it used to be expected.

It usually we thought it was 5% of DVT,
but some newer studies think that
we are seeing about 18 to 20%
of lower extremity DVT is actually caused
by iliac vein clot.

So important to remember that and include certainly
whenever you have monophasic waveforms.

If you can't see as high as the iliac vein
and you can't find the cause by ultrasound, then you need
to enlist either CT or MRI to look at the proximal vessels
and the surrounding soft tissues.

Upper Extremity DVT

Let's turn now to upper extremity DVT,
which is actually an important cause of morbidity in patients as well as pulmonary embolism.

So this is just an example
of a line induced clot in the right axillary vein.

So is it the same as lower extremity DVT?

And it used to be taught that upper extremity DVT was not
important for one thing, it was very rare.

Small percent of all DVT,
I think these numbers are climbing now considerably
because we have so many catheter induced clots.

Primary DVT is related to enlarged muscles
actually, which will occlude
or impress upon the underlying veins,
or it can be due certainly to patients
with a hypercoagulable state.

And it's very rare. Secondary upper extremity DVT is quite
common and this is related to these central lines
or peripheral venous catheters
or even pacemakers which induce thrombus upon them.

And up to 25% of patients
with lines actually will form clots.

So pulmonary emboli are seen in anywhere from 12
to 30 per 6% of these patients, depending on who you read.

And the mortality from this PE is actually the same,
is in patients with lower extremity DVT as the associated
cause for the pulmonary embolism.

So in primary upper extremity DVT,
there's about a 6% incidence of pe.

But again, in these patients with high risk
and hypercoagulable factors, the incidence
of PE starts climbing to 13%.

And in catheter induced DVDs,
the incidence
of PE in association is as high as 17%.

So you can see that
these high risk in catheter induced patients certainly do
have high risk for pe.

What's the clinical presentation?

Well, these patients unfortunately
not all have clinical symptoms, only 60%
and the symptoms are quite different.

So they can present with pain or swelling
or erythema, dilated, superficial veins, cord, neck
or shoulder pain, facial swelling.

And actually less than 50% of patients
with symptoms actually will have a documented DVT.

So this is a difficult clinical diagnosis.

In the lower extremity we talked about compression being
the mainstay in the upper extremity.

Not all of these vessels can actually be compressed.

So the internal jugular, the basilic, the brachial,
the axillary, and the distal subclavian veins
where we can do compression, that's still the mainstay just
as in the lower extremity.

However, behind the clavicle
and behind the clavicle
and sternum junction, we need to be using color
to see the subclavian
and brachiocephalic veins respectively.

And in this case, if you don't see flow in those areas,
that is considered abnormal.

The spectral doppler will document normal
variability with respiratory and cardiac cycles.

However, spectral doppler alone can be insensitive
to clots because in the upper extremity we develop
collaterals fairly quickly
and you can see nice variability in these
collaterals as well.

So the accuracy of upper extremity DVT not as good
as we are in the legs.

There's a large range of sensitivity,
but the specificity if you see a clot is very high.

And a prospective study compared to venography
yields basically a specificity and sensitivity of about 82%.

Again, our compression exam is the most specific
incomplete filling on colors the next.

And then lastly, the spectral waveform analysis is
only about 50%.

So just a reminder for the normal anatomy, the cephalic
and basilic veins here are superficial veins.

So a lot of our lines are placed in here in the cephalic
or certainly in the basilic.

So the clot
that occurs on those lines is considered a
superficial clot until it travels into the axillary vein.

The deep veins include the internal jugular, certainly the
subclavian, the axial, and the paired brachial veins.

The normal compression examination
is the same as in the legs.

You can see here is the jugular vein
and here's the carotid below it.

When we compress, only the carotid is left.

The same thing in the axillary system.

The axillary vein compresses completely,
the artery is the only thing left.

Same thing for the brachial veins,
the paired brachial veins here.

And here's the basilic vein over here,
it goes away completely.

An example of thrombus here in the subclavian vein you can
see is an area which is not compressible.

And again, on the color you can see partial obstruction
of color flow secondary to this marginal thrombus.

The normal spectral tracing is similar to
what we saw in the legs,
especially if you're further out in the arms,
you can see its pulsatile comes back towards the baseline.

Sometimes you'll see a little bit more variability.

And some of that has to do with the cardiac pulsations
that are also reflected in these vessels, which you can see.

Nice pulsatility all the way from the axillary vein
through the subclavian vein
and into the brachiocephalic vein here.

Alright, so is there a DVT here?

Well, we can see that there's color flow here
and we're in the subclavian vein, so we're
beyond the point where we can have compressibility.

But when you notice this waveform, this is not
as variable as I showed you on the previous slide.

And we look more centrally.

Here is the brachiocephalic vein here
with a nice pulsitile waveform.

And sure enough, in between the two,
where you'd expect it is a clot.

So this is sort of analogous to
what we were seeing in the leg.

The part that's closest to the heart still has the nice
pulsatility and then that's interrupted here by the clot.

Notice that there's a collateral already here
forming alongside.

And then in the more distal vessel,
you can see this more monophasic waveform.

If this were emptying better via a collateral,
this may not show that monophasic waveform
and it might actually be fairly pulsatile.

Just an example for the upper extremity is there a
picc line, DVT.

And here in the subclavian vein you can see nice pulsatility
as well as in the axilla.

And notice here is the line.

You can see a little bit of flow around it.

And just to be aware, again,
your color flow can sometimes obscure the clot.

You really do wanna look at the gray scale carefully along
the clot along the line.

And therefore the gray scale here helps
to make the diagnosis not the spectral
and not necessarily the color.

You wanna be sure of the gray scale as well.

Notice the nice normal lumen
that you can see just a small amount of it on this deep side of the catheter.

So here's just another example here, A patient
with a subclavian vein clot.

You can see here is the monophasic wave form.

And you can see a lot
of thrombus here sitting along the catheter in the medial
aspect of the vessel.

The important thing to remember is do a complete examination
because sometimes these patients will have other clots in
other places and there's an additional thrombus in the right
internal jugular vein.

So make sure that you examine both the internal jugular
veins in each patient.

Pitfalls in Venous Ultrasound Diagnosis

What are our main pitfalls?

Well, certainly there are the technically inadequate
examinations when patients are very large
or if they have tens and swollen
limbs that we can't compress.

And that could lead to a false positive diagnosis.

So therefore we wanna use color in those patients,

these duplicated segments.

If only one is thrombosis, you may miss it
because the other one will be normal.

And just remember the nomenclature issue,
that distal saphenous vein
and those muscular caffeines really are treated
as deep venous thrombosis.

So just examples here, A DVT pitfall, we can see an artery
and a femoral vein here.

And what do you think the pitfalls going to be?

Well, remember the duplicated segments.

So when we actually look a little more carefully
and a little bit deeper here is a large vessel here deep
to this artery,
which is actually a completely occluded femoral vein.

And so we wanna make sure to think about that
and recognize that there is a large gray scale clot here.

Again, here's a patient with a common femoral vein
and popliteal vein with sort of a monophasic waveform.

So and a very nice pulsitile waveform here in the
common femoral vein.

So remember that you need to examine all the segments
and don't skip anything
because here is an isolated clot actually in the femoral vein.

And again, there's a duplicated system here.

Don't ignore any segments
because you may have isolated clots in the thigh without
associated clots in the calf.

Again, a patient who has a color doppler pitfall,
we can see the artery here, we can see
what looks like a vein here,
but this is very far away from the artery.

And so I've labeled here,
this is the popliteal vein actually sitting back here.

So there's a large clot in the popliteal vein.

You do not wanna mistake a collateral
for a patent vessel.

And the distance between the two
of these is actually the most useful thing to recognize
that you're dealing with a collateral
rather than the native vessel.

Okay, so an unknown for you is a, this a deep vein
or a superficial femoral vein thrombosis.

And I'll give you the clip again.

So we're located up in the common femoral vein here,
and this is a large clot, which is in the saphenous vein.

And we will report this as positive
for a deep vein thrombosis
because the greater saphenous vein is treated
as a deep vein in its cephalad portion
in those very distal two centimeters,
or the most cephalad two centimeters of the saphenous vein.

You wanna make sure that the clinicians treat this
patient as a DVT.

Again, here's another example.

Patient DVT or superficial venous thrombus.

Here is a clot again that you can see here.

It's only in the saphenous,
but when you look carefully with color, you can see
that this clot is actually protruding into
the common femoral vein.

And again, this is the risk of those saphenous vein thrombi
that they actually enter into the common femoral vein
and do become deep vein thrombosis.

What about this patient? Here is a patient
who had a thigh sarcoma.

So he's got a cancer and he's at high risk.

And when we did the initial study,
the patient had diffuse leg pain
and the sonographer reported this as negative.

So what's missing in this exam?

And that's sometimes the hardest thing to recognize.

And you can see here the posterior tibial vein
has two vessels.

The perineal vein has a little color flow here
and the anterior tibial vein you can see flow
and something as spectral tracing from something up here.

So what's missing is the peroneal veins,
of course are paired as are the posterior tibial
and the anterior tibial veins.

So we brought the patient back and repeated the exam
and we looked at the peroneal veins in particular.

And when you do that,
you can see here there's
absolutely no compression there.

You can see one vessel here,
but deep to it is another vessel which has a clot within it.

So don't emit that gray scale compression exam
and make sure that you identified paired veins in all
of these three calf tributaries.

What about chronic DVT? That's a pitfall for us.

We can characterize that if we see focal
or diffuse wall thickening
because of course these patients don't need to be treated.

So here's a patient on initial exam, you can see a clot,
which is expanding the lumen.

And then three months later you can see
that this clot is much smaller
and the vessel walls actually are
contracted towards one another.

So this could be read out certainly as a chronic DVT.

You're more certain
of this if you can see more contraction of the vessel
or if you see calcification or webs or scars.

So here's a patient actually with some slightly calcified
or a very genic web within the vessel.

So this is certainly a chronic DVT.

This patient does not need to be anticoagulated.

Here's another patient with a clot
that has calcium in it.

So this again should be a chronic clot.

Notice here, again, the color can obscure this.

You wanna make sure you look with gray scale as well.

And that way you will see the clot as well
as see the calcium within it.

And lastly, you always wanna think about alternative
diagnosis, always image where it hurts.

So a patient with left leg pain
and swelling, this happens to be a large baker cyst,
which certainly can mimic the symptoms of DBT.

Here's a patient with arm swelling
and we found an abscess with gas within it.

And so there are many other causes of alternative diagnoses, certainly masses, tumors,
ruptured muscles, et cetera.

So always look where it hurts to make the diagnosis.

Serial Ultrasound and Follow-up

What about serial ultrasound?

Well, that was previously recommended at one
week in all patients.

However, now we basically do not recommend
that if the first ultrasound is negative
unless the patient is very high risk.

For clots, it is safe
to withhold anticoagulants if you have a normal initial
examination and do serial ultrasound.

And lastly, follow up is unnecessary if
unless the patient has persistent symptoms
and if the patient does have symptoms, we
would encourage follow up examination in
about five to seven days.

Conclusion

So in conclusion, ultrasound is highly accurate
to assess lower extremity and upper extremity DVT.

Gray scale ultrasound is central to the diagnosis.

We use color to facilitate the gray scale exam, especially
where compression cannot be performed,
and that's particularly in the upper extremity exam.

And lastly, we wanna use spectral doppler
in the bilateral common femoral veins to assess
for the proximal extent of clot
and to look for proximal obstruction
and also in the upper extremity
to look at the central veins.

Remember to be aware of duplicated systems
and collaterals that can be confusing
and lead to false negative diagnoses.

Be sure to image where it hurts,
especially in the calf in order not
to miss those muscular clots
or other causes of the patient's symptoms.

And remember, a technically adequate negative DVT exam in
the leg does not necessarily require follow-up if the
patient does not have persistent symptoms.

So thank you very much and I hope you found this helpful
and encourage you to use ultrasound as much as you can
to examine your patients with leg and arm symptoms.