Extremity Venous Ultrasound: The Present State - HD

Historical Context: From Venogram to Venous Ultrasound

Good afternoon, John.

Good afternoon, audience. I have no financial disclosures unfortunately.

And does anybody know what this is?

This we have replaced over the last 30 years.

This has pretty much died down and no one even knows what it is.

When you look at this, you realize we used to read these and think we had absolute certainty about what was contained within them.

This is a venogram, and frankly, it was probably not a gold standard.

And really this came along in the mid to late eighties.

The Simple Technique of Venous Ultrasound

And it's venous ultrasound, an extraordinarily simple technique, which we probably have tried to make a little more complicated.

But this came from the first article I wrote in 86, and all it showed was that if you dimple the overlying skin, a normal vein would collapse and an abnormal vein, which would be located here. Won't collapse. It was that simple.

And you can see here a normal vein winking at you down below, and an abnormal vein over here in spite of compression in the saphenous vein, the femoral will not collapse.

And it's that simple.

A lot of other things we've added to it.

Consensus Panel Topics

The topics for discussion this afternoon is talk about compression and then look at some of the other items.

Many of these items may be somewhat new to you.

They came from the consensus panel last year that Larry Edleman headed up.

We're waiting for publication of the paper soon.

Some of these are gonna be a little different than maybe what you've done before.

There was a lot of sentiment that one would only do venous ultrasound with a certain degree of suspicion.

And that has become from the image wisely, the internal medicine group, everything.

We ordered too many imaging tests.

This should be sufficient screening for this.

Appropriate Use Criteria: Screening with D-Dimer or Wells Score

So one of the items that the consensus panels proposed that you have either a D-dimer or a Wells evaluation that is positive.

Don't panic, it's not gonna decrease your volume significantly.

'Cause this is the Wells criteria. You need two points here.

You can look at this and realize, you probably can come up with two points on this without too much difficulty.

Bedridden for three days and localized tenderness or vein swollen or leg swollen, it doesn't take that much, but there has to be some screen.

In this day and age, there's just too many studies done without any real probability.

Defining the Complete Duplex Ultrasound Exam

And the test of choice is the complete duplex ultrasound test.

Now, what is a complete duplex?

It's compression of the deep veins from the inguinal ligament using selected Doppler.

And we evaluate the calf, particularly the posterior tibial and the peroneal veins.

You're gonna say, gee, that's maybe more than I really think and need.

But it's really what the consensus panel came up with.

And we were driven by vascular medicine people, vascular surgeons, ER docs.

Everybody was on board here.

And this is your normal anatomy.

You see the common femoral running down to the calf.

Variations in Venous Ultrasound Protocols

What kind of tests are performed by different people?

The two point compression exam is really two areas that are compressed, the femoral and the popliteal and that only.

Who uses that?

The ER docs find it very quick and slick and pretty good.

The problem is there's a gap here.

There is no definition of, and no definition down here.

There's two gap areas that are not included, but for the ER docs, they kind of attest to this is pretty good, but it is not as good as what we really can do.

And then we have the extended compression ultrasound, and this is what we started out with in the eighties.

Remember any of those old enough to remember there was no Doppler on ultrasound machines in the mid eighties, late eighties.

That came along later.

So you basically just looked at this area down to the knee and just below into the popliteal.

Then we've asked people to do complete compression ultrasound, which runs all the way down to the calf, but what the consensus panel is recommending complete compression ultrasound and with some Doppler evaluation at the common femoral, and look at both sides and make sure it's symmetrical and using some Doppler also in the popliteal.

So that is what the consensus panel is asking people to do.

And that's what the SRU position paper will be.

Evaluating the Calf Veins: Direct vs Serial Imaging

Now, how to do calf vein analysis was done one to two ways.

You did direct imaging.

What you should see down here, and you're looking at the tibial veins that are occluded, or you could do serial imaging and serial imaging.

The concept was, I'm not gonna look at the calves.

And if the patient has continued symptoms come back in three to five days, most of these, most calf, most clot actually originates in the sural veins down here, and then in the gastrocs and these other calf, everything starts down below.

If you're not looking down there, you're leaving something exposed.

Case Study: Propagation of Clot

This is the very first case where I ever had, this is about 1985, 86, where I looked at and I realized the importance of doing, being willing to do a follow up study.

I was kind of young and stubborn, and I did this study and I was just espousing the technique, its value, and the popliteal here compressed beautifully.

The physician, one of his physicians called me back and about a week later and said, my patient's leg getting worse.

And I said, he doesn't have DVT.

And then he kind of persisted and I said, send him back, and this is what he looked like nine days later.

And then I realized the popliteal was full of clot.

This does happen, and it happens routinely that you can have propagation of clot from the calf vessels.

If you don't look at them, that's gonna happen.

So you either look at 'em or do serial imaging and the committee and the consensus panel says, look at it.

Advantages of the Complete Duplex Exam

What's the advantage of doing this complete duplex ultrasound?

The best thing is we cut out the Tower of Babel.

Everyone's on the same page, everyone does the same study.

You don't have this issue.

You can detect calf clots present probably in 10% of the time, just isolate to the calf, never make it up to the popliteal or one of the higher vessels.

You don't have to do a second look study routinely.

Most of us don't do second look studies routinely, and we only do a second look if there's a real issue, if the patient persists in having problems and there's what's the number's high, kind of hard to come up with, but probably something around 16% of calf clots gonna make it into the popliteal.

And then also your symptomatic areas get evaluated.

In the complete duplex ultrasound exam, we solve a lot of problems and kind of bring a lot of things to rest calf clots still remains a challenge though.

Challenges in Detecting Calf Clots

We have great sensitivity for clot in the popliteal and above, probably 98, 99%.

It is much better than the venogram, trust me.

And then the calf, it drops off not as good.

The problem is what is the modality?

The technique that's most effective is compression.

And it's hard to compress some of those calf veins.

The gist of the anatomy is protected by the bones and the fascia.

We only did the calf in the past if the patient had persistent or worsening symptoms, but we had pretty good results.

The outcome analysis showed, patients weren't dying of PE in spite of this.

We got pretty good.

Here's a soleal vein clot we could pick up and we were doing okay, so the calf, calf veins, people always wonder what we're talking about.

Anatomy of the Calf Veins

In the initial venous ultrasound exams we did in the eighties that go from the femoral to the popliteal, they do go below the knee.

I have been involved with med mal cases many times.

A radiologist will say, I never go below the knee.

That was not a part of the problem.

Popliteal goes below the knee joint and almost every human being I've ever evaluated, it goes down a couple of centimeters.

Don't use the term, they don't go below the knee that really gets the plaintiff's attorney, they love that one.

And then you have posterior tibial and peroneal veins paired veins in the deep system.

And then we have two other characters, the gastrocnemius and the soleus.

These are muscular veins and a lot of people just blow off the significance of these, but these are deep to the fascial planes.

So they are technically deep veins.

Larry and I at least I was, but we were at the consensus panel, the vascular medicine people said they wanna know if there's clot in the muscular veins.

That is very important and will influence them significantly.

Maybe we don't think much of 'em, but it does have value.

Medicolegal Implications

I alluded to the medical mal case, and I have been involved with several of these.

The Tower of Babel problem here is exuberant.

You have the AIUM saying, you gotta look at the calf veins ACR says, when it's appropriate, when it's necessary because of symptoms, and all of this can be used against you so readily.

I've been involved with cases where the radiologist didn't look at the calf veins.

They ask him what he knows what AIUM is.

They read the AIUM criteria, they bring some expert in and says, you should have looked at the calf.

Next thing you know, the guy lost the case.

This would be solving a lot of problems.

The SRU basically says, look at the calf veins routinely and we won't have a problem.

Treatment Considerations for Calf Clots

Treatment of these, yes or no, the vascular medicine people on the panel extended let us decide if you want to treat, you shouldn't be making that decision.

We'll look at the whole ball of wax in the picture.

Don't forget, treatment doesn't dissolve the clot.

But what it does, it prevents further progression and down the line, you won't have huge insufficiency and develop a lot of varicosities.

That's probably the most important reason.

The complete duplex ultrasound isn't perfect because of the calf.

If you had persistent symptoms with the complete duplex ultrasound and the guy was getting worse, you should repeat that study too, because we can miss calf clot with this test.

I did allude to the fact that when you do the femoral evaluation with Doppler, you're looking at both sides for symmetry.

That's to assess uphill issues, compression of a vein or an occluded vein uphill.

Clot Propagation from Muscular Veins

What about the gastrocnemius and soleus veins, which are muscular veins?

They certainly can propagate into the tibial and peroneal.

They can extend all the way to the popliteal.

In about 3% of patients, there's data that says if you had clot on there, it's gonna either decide to go away or make its position established in about two weeks.

This slide is from Larry, actually, I was trying to figure out where it's from, but it shows a small clot in the soleus on an 8/14 and then a clot, you can see here, making its way into the tibial vein on 8/18, and then the popliteal full of clot on 8/26.

That took 12 days to make this progression.

But it happens.

If you were not to have seen the soleus clot on the first study and the patient now was getting worsening symptoms, a week later, you should repeat the study.

It's that simple.

Differentiating Symptomatic and Asymptomatic Calf Clots

Now, what is the issue of the calf clot?

Why they're so difficult?

As I alluded to, compression isn't available.

But the real issue is there's a lot of small calf clots that exist in studies that are really asymptomatic and they're less important.

You don't want to get too carried away with those.

You have the symptomatic patient who has pain in the calf, swelling in the calf.

Then you have asymptomatic where you have focal clot on valves.

And these are pretty routine.

You sit here until the break.

When you stand up at break, you're gonna flick off these little clots from your valves.

It's routine, I firmly believe everyone does this and that should not be held as something that we can't look for.

This is not something you need to detect really.

There's articles that have looked at in the orthopedic literature for years talking about how asymptomatic DVT when you're looking at patients sort of screening them routinely, you're gonna miss a lot of the calf clots and that's probably true.

We know we can't compress.

A lot of these clots are very small and therefore it's not that important.

Understanding Small Asymptomatic Clots

I'm going to just divert for a second to look at these calf clots, these small asymptomatic ones.

What are they?

Here are your valves and the valve cusps close when you stand up, they come together, blood rushes down, they collapse and they prevent flow from going downhill.

Clot can sit on the valve cusp and it sort of forms like this.

When you stand up, this little thing kind of flicks up and goes through your lungs and they usually never get this big.

The problem is if it gets this big, it starts to get significant.

That's the unusual aspect.

Hopefully it doesn't happen very often.

Here you see a patient with color Doppler or power Doppler, and you can see there's a behind the valve here, there is a clot formed.

You can see this is a more dramatic picture of it.

Here are the two valves and you got stagnant flow occurring behind these valves.

That stagnant flow is where as you sit here and you're not getting muscular contraction where little tiny clots can form.

We're not talking about the clots that do this in the lungs and PE we're talking about these little tiny dots that form down here in the lung, which I call normal clots of daily living.

There've been reports in the literature of routine CTs of the abdomen.

The lung base is 4% of people that pick up small dots, small PE that's in multiple studies with high definition CT scanners picking up.

4% of people have small clots.

They're the same clots that if we scan everybody here in this room after they sitting for two hours would probably have.

It's this little clot that sits here.

This is not what we're worried about, frankly.

It sits here and it causes this little dot.

These are pretty much normal little devils.

I diverted there just to discuss what the calf, what we're not really worried about.

We're worried about the occlusion that is occurring in the tibial peroneal, soleal veins.

The Evolution of Deep Vein Thrombosis (DVT)

Now the last important topic, and one I think that's very, very important, is the evolution of DVT.

If you have clot in the veins, it stabilizes with treatment in the course of about a week to 10 days.

That clot sits there.

It stabilizes, don't forget, heparin does not dissolve clot.

You put patients on heparin and they got clot load there, they're not forming any new clot.

What happens to that clot?

It kind of stabilizes, then it undergoes a process of healing.

That can occur over almost six months.

Most of it probably occurs in the first three months, but up to six months.

Do you heal completely?

About half the people heal completely and about half don't.

What's the best predictor of how much healing you're gonna get your age, the younger you are, the better you heal and clot load large clot loads and probably not gonna completely resolve.

When you have this effect, this is left behind some material in the vein.

I would guarantee you that if you were to look at a typical day in the United States, I would bet somewhere between 10 to 20% of the patients who are called acute DVT actually have, do not have acute DVT instead have this chronic post change.

If you looked at a hundred patients, 50% are gonna go to normal and 50% will be left with some chronic change.

The chronic material is stiff, it reduces the size of lumen, but the lumen is still patent.

There's no inflammation going on.

The baseline can occur over three to six months.

The problem is in Europe, they've established the fact that if you see this residual scarring material, that the patient should stay on anticoagulation longer because what's the number one risk factor for acute DVT is prior DVT and they're claiming that this scar material actually sort of sets you up for additional issues.

Recurrent DVT is difficult diagnosis and often masquerades as acute DVT.

Chronic Post-Thrombotic Changes

What's the terminology?

The terminology of the committee?

The consensus panel decided that you should call this residual material, which is sort of a scar, but give it the name chronic post thrombotic change.

So chronic post thrombotic change.

And what happens here, if this is a transverse image of your initial vein, you had clot, it can be asymmetrical, but frequently is a roto-rooter effect where it just kind of drills through and you have a new lumen.

A new lumen here is all you can expect to compress.

You can't expect that the outer wall now is gonna touch the outer wall because it is post thrombotic change here.

And this is all you're going to see that this going to change.

In summary, you have an acute clot and it can go to normal 50% or it can be left with this post thrombotic change.

My point I made several minutes ago was unfortunately this probably is routinely diagnosed as acute DVT in most scenarios and puts the patient back on anticoagulation when it's totally unnecessary.

The evolution see this, this is an important point and the committee thought it was a point that was not well understood.

Acute clot evolves.

It can, what's left in 50% of people is called chronic post-thrombotic change.

The residual lumen can exist with still some scarring there and the residual lumen can contract.

Diagnostic Tips for Recurrent DVT

If you have a patient come in and you don't know if, they said they had an episode before and they had chronic, but I don't have the images, I don't know where it was or anything, you can do one thing, you can check a D-dimer and if the D-dimer is negative, you should not have acute clot.

The other thing you can do is you do the study and repeat it in one to two days, looking to see if there's any change or evolution.

Acute process will change.

A chronic process is gonna sit there and not change.

You gotta have some alertness and concern that this is in the possibility.

Conclusion

All right, thank you very much.