Sonographic Evaluation of Lower Extremity Venous Disease - SD

Introduction

Hello, I'm Larry Needleman.
I'm the medical director at
Thomas Jefferson University Hospital.
Today we're gonna talk about venous disease,
both in its acute form of venous thrombosis
and its chronic form with venous insufficiency.

Risk Factors for Acute Venous Disease

Before discussing the sonographic appearance
of venous disease, let's discuss a bit of the risk factors
for acute venous disease.
These have been described more than a century ago by
and talked about the three aspects of
the patient population who is prone
to develop deep venous thrombosis.
The first group of patients who have venous stasis,
typically from bedrest or immobilization.
This is very commonly occurs in the inpatient population
and occurs following surgery.
The other large group is those with hypercoagulable states,
either those that are born with an imbalance of their
ability to coagulate
or those that develop this as a result of
Particularly cancer.
And there are certain cancers which are more associated
with this, such as pancreatic cancer and gastric cancer,
and these are described as the trusso syndrome.
There are also situations where people are prone
because of therapy
and one of the more common ones is heparin induced
thrombocytopenia, which can lead to
a paradoxical increase in coagulation coagulation.
Finally, patients
who are traumatized either from nearby fractures
or from catheter lines
that are placed in the veins can also develop
deep venous thrombosis.
This is more of a factor in the upper extremity,
but can be seen in the lower extremity as well.
To summarize, the risk factors
for deep venous thrombosis are many, including age
above 40 years old.
Those patients that have surgery,
and particularly those with surgery for malignant disease
orthopedic patients, those patients who are at bed rest
for greater than four days.
People also with any kind of chronic medical conditions such
as cardiopulmonary disease.
And then there's prior venous disease such
as previous deep venous thrombosis, the presence
of varicose veins and obesity.
Another area that's very interesting
for many people is the presence
of DVT following long plane trips,
and this is related to the particularly long plane trips
that some people now are more prone to.

Importance of Venous Ultrasound for Deep Venous Thrombosis

Venous ultrasound is an important part of the,
evaluation for deep venous thrombosis
because this is an extremely common disease
and pulmonary embolism is considered one
of the major killers of inpatients that are preventable
and prophylaxis is getting more and more while it's spread,
but patients are still,
at risk
for deep venous thrombosis.
And the most important
aspect is that the clinical diagnosis
of deep venous thrombosis is not reliable.
Those patients who have symptoms often do not
have deep venous thrombosis.
They have other processes such as chronic venous disease
or musculoskeletal or arthritic processes.
On the other hand, asymptomatic deep venous thrombosis
is rather common and can be lethal.
And in one study, only 10% of the people who died
by pulmonary embolism had
preexisting deep venous thrombosis symptoms.

Review of Venous Anatomy

A review of venous anatomy
is broken up into what's called the central veins.
Those veins that are,
from the thigh
to the knee, the common femoral vein
and the femoral vein,
the word superficial femoral vein is now not a considered
part of the accepted nomenclature and should not be used.
And then finally, the popliteal vein,
which is formed
by the confluence of the major calf veins.
So after we deal with the central veins, we are dealing
with the calf veins
and they are two different sets of veins, those that lie
between the muscles, the posterior tibial perineal
and anterior tibial veins
and those that lie within the muscles, the so-called gass
and sole veins that are present
just as there's a deep system,
there is a superficial system which is draining the
subcutaneous tissue.
And these veins fall into several categories,
the large veins of the superficial system, the great
and small saphenous veins.
Again, these are now the new accepted nomenclature
for these veins as well
as the other veins lying in the superficial tis system
that are tributary to these veins.
There is also veins that run between the deep
and superficial system, the so-called perforating veins,
and finally the veins that communicate
between one part of the system and another.

Venous Valves

Another aspect of veins are their valves.
These are quite important that they control
the direction of blood flow.
They're more numerous as you get further,
distal in the legs.
So the C veins have many,
many more valves than do the veins in the thigh or pelvis.
A long axis view of the vein shows
that the vein is slightly distended
in the region of the valve.
That's a sinus. Here are the fine,
valves
that can be seen here and you can see that there are echoes
that exist behind the valves.
This was not the venous thrombosis,
this was just blood which is collected behind the valves.
And these were easily removed with augmentation distally.

Symptomatic vs Asymptomatic Deep Venous Thrombosis

Deep venous thrombosis can be symptomatic or asymptomatic.
The location of the thrombi varies in those two groups.
In the symptomatic DVT patients, the thrombi tend
to be larger and involve the larger veins.
As we can see from this study from the 1980s using
venography, 84% of the thrombi that were present in patients
with symptom were in the proximal veins while only 16%
of the thrombi were present in the calf veins.
This is in distinction to their group of patients
with asymptomatic deep venous thrombosis
In screening surveillance.
Venograms, approximately 50%
of the thrombi were in the proximal veins
and 50% of the thrombi were in the calf veins.

Natural History of Venous Thrombosis

When we look at the natural history of venous thrombosis,
we recognize that thrombi tend to begin
in the small veins of the calf.
As this process develops,
the thrombus doesn't necessarily grow continuously from the
calf into the more proximal veins,
but that the thrombin now
is seated in other veins which are present.
So independent thrombin are present.
That means when you scan patients,
you may find thrombi in one vein, see a normal segment
and then see thrombi in a second venous segment.
The thrombi begins
behind those vein valves typically in the C veins.
As it gets bigger and bigger,
it's gonna be free floating in the lumen of the vein
and then eventually actually fill the vein
and attach completely to the wall.
Even as the body is creating a thrombus
and it's getting bigger, the body is acting on this
and beginning to retract the vein.
So there's a natural ebb and flow and growth
and regression of the thrombi.
As the thrombi begin tends to age,
it will separate from the wall.
And this is why when we see the most thrombi clinically,
we can see flow around the edges of the vein
and also why we can see contrast flowing
around the veins on venography.
As the thrombi matures, it can
start to pull back and retract against the wall holes
or lines may appear within the veins
equaling recanalization.
And at a, at several months you may not see any evidence
of the thrombus in the vein
or in about a third of patients see some scarring
or a filling defect completely filling the vein may be
present in about 15% of patients.
We can see a picture of this
where we can see on the top the free floating nature
of the thrombus coming from behind the vein valve wall.
And then to the left, the vein completely fills
with thrombus and then the recanalization,
as the thrombus breaks down the middle on the right,
we can see with the effect of retraction where part
of the wall
is separated and it gets closer
and closer to one remaining wall.
And then a third part of retraction where it actually
separates from both ends of the wall, leaving a narrow band
of tissue or fibrosis in the middle,
a so-called weblike change or signi eye.
And we can see any
or all of these in patients who have chronic venous change.

Ultrasound Technique for Venous Evaluation

Venous technique is
to typically use a linear array transducer
and to scan the patients in the transverse plane,
the frequency is appropriate to the size of the leg.
Most patients can be scanned
with a five megahertz transducer,
although a very large MOUs leg may require a lower
frequency, typically vein compression is performed every
centimeter or every one to two centimeters
down the leg sector.
Transducers can also be used in particularly helpful
in some patients when compression is difficult
to give a wider compression on the patient.
Transverse images are adequate to document a normal study,
but long axis are very helpful,
particularly when they're filling defects.
To get a sense of the contour
of the thrombus which is present, we look at echogenicity,
but we're particularly interested in what
and how the thrombus fills the vessel, the size
of the overlying vein
and what's happening to the vein, whether it's distended
or compressed, we typically want the patient
to be in a relaxed state with the heart lying
above the veins so the patient is in the supine
or reverse linberg position
with a thigh gently externally rotated.
For the popliteal fossa, we want the leg gently bent
and not hyperextended.
Any position where you can get
to the popliteal FOSS is acceptable, whether
that's a decubitus prone or a foot
and lap position scanning from back to front for the calfs.
Some investigators very much like the patient's leg dangling
or sitting in your lap
and scanning from a sitting up position, other people use
a similar supine or reverse fromberg position.
The short axis is used for compression.
The long axis, however, is the
preferred methodology for spectral doppler
and here we can see a long axis of the caffeine
being studied in with a spectral doppler transducer.

Doppler Findings

Now the normal findings in doppler are of variation,
which occurs with respiratory changes.
This is so-called phasic variation.
And when this gentle changing with respiration is absent
and there is no change between the breathing,
the vein signal is called continuous.
Additionally, if the vein is completely occluded,
there won't be flow within the vein and anine signal
and is another sign of abnormal disease.
Here is a spectral doppler of a normal femoral vein
and we can see several things.
First of all, the vein velocities or changing over time.
Secondly, we can see
that the peak in those velocities actually are changing over
time with the difference between the peaks being affected,
not by cardiac effects,
but rather by respiratory effects where the
where the peak velocities change with respiration,
on the other hand, the continuous signal has no changes
either due to breathing or due to cardiac effects.
And there is a differential diagnosis associated with this.
There is venous obstruction either due
to intrinsic venous process such as deep venous thrombosis
or extrinsic obstruction.
If a patient does have scarring from the veins from prior
thrombosis, the vein may have been continuous from
that prior disease and never renormalize.
So in the differential, we must also consider
that there was a prior thrombosis with collaterals.
And so history is very important when evaluating the patient
with a continuous venous signal.

Compression Ultrasound

Compression is quite simple.
The artery and vein line next to one another when
compression is placed, the vein disappears completely.
And so here you see the artery and no vein.
The
vein
compression usually is quite gentle
and usually easy to accomplish.
On some patients with venous hypertension,
it may be difficult to completely compress easily,
but if you see deviation of the a artery,
then the corresponding vein should,
should be completely collapsed.
There is one process by which people who record images
for non-compressible
and compressible sometimes leave a little bit of vein so
that you can see where the vein was
on the compression images.
I don't feel that's a very good idea
because it's difficult to take
to separate a partially compressible vein from a completely
compressible vein with this.
So I like pictures where I can't see the vein completely,
where I understand that the vein is disappeared
because it's completely co-opted.

Differentiating Acute from Chronic Thrombosis

Now, veins that have residual
material within them or do not compress completely
also have a differential diagnosis.
First, let's go to the pictures.
On the left, we can see that there is a vein
with a echogenic heterogeneous,
material within it.
And when we look with compression,
what we can see is the vein has gotten smaller
and a little bit closer to the surface
and that there is a difference in shape,
whereas the acute thrombus was rounder on the left.
On the right, we can see it's taken on a bit more a belong
shape, meaning that it's deforming and changing shape.
This deformable, non-compressible vein is typical
of acute deep venous thrombosis,
but the vein may not go away for other reasons.
Besides that there could be scarring in the vein
and material in the vein that is not acute
and the vein would not go away
or that the technical factors
where the vein was not compressed adequately.
So how do we differentiate from acute venous
thrombosis from scarring?
Acute venous thrombosis tends to have veins thrombi
that are somewhat soft and changeable
or deformable with compression.
As a rule, the veins are larger
because the veins tend to engorge.
The thrombus tends to engorge the vein.
When we look at the outlines of the thrombus, it tends
to be smooth and in some patients we can actually see the
thrombi moving in real time.
This free floating thrombus is always
acute venous thrombosis.
Again, the deform ability of the vein
and the non compressibility is our marker for acute deep.
His thrombosis. Long axis
fuse can be helpful in that.
We can see the distension of the vein here at the cordal.
End of the picture of the vein is small
and you can see that it descends
quite dramatically in the middle
and at the cephalad end
and we there is thrombus all the way through
above this cephalad component.
In addition, I want to point out the genicity
of the of the thrombus.
It is said that fresh thrombus tends to be anti coic
and older thrombus tends to be epigenic.
And while that's true as a usual rule, most thrombi
with which are acute with modern equipment tend to be
somewhat echogenic and be somewhat heterogeneous.
And so echogenicity per se is not a criteria
for separating acute deep venous thrombosis from scarring.
Color doppler can be used
to look at a filling defect in the vein,
we can see the echogenic thrombus here
and we can see some of the filling defects in the vein here
with the corresponding artery
being colored in blue.
However, this is not as helpful a sign as
compression and compression ultrasound remains the
most evaluated sign
for differentiating a normal vein from an acute thrombosis.
I tend to use the word chronic venous changer scarring
rather than cr chronic venous thrombosis because
after about two weeks the material in the vein is no
longer a thrombus.
It has re endothelial.
And so another term I think is, is preferable.

Appearance of Chronic Changes

As we look at what chronic changes in the vein look like,
we are looking at the evolution of the
material in the vein from retraction recanalization.
And so the material in the vein tends to no longer be soft,
it tends to be stiff, it heals irregularly
and so it has an irregular surface.
You can get those web-like changes
as we've described before.
Again, if recanalization is nearly complete,
you may just have a rim of wall thickening.
And in terms of size, the vein tends
to be normal sized or small.
In this long axis view, we can appreciate the fact that
the material in the side, the vein is heterogeneous
and perhaps more echogenic than usual.
We can see some bright echogenic reflectors
inside this scarring as well.
But the more striking abnormality is the marked irregular
shape of this material.
Inside the vein indicating that this is a result
of the retraction of the material, you can see
that the vein itself is normal sized
here on the other hand is an area
of syne eye here at the cephalic end of the vein
with this linear change which is present.
And I also want to draw your attention to the vein wall.
Long axis views can be quite helpful in that we can see
that the wall is pulled in here,
which would not be a sign of acute disease.
This is again, a sign of scarring.
This pulling in effect here at the cortal aspect
of this material, we see this material on top of the,
of the syn eye or a thickened syn eye.
And the two could be differentiated
by compressing in real time.
If that material is soft
and lying on top of the thin white line, then it's likely
acute on chronic disease.
If on the other hand this material is stiff
and unchanging, it's just a thick web like change
in short axis, we can often see many
of the same findings in scarring.
Again, some of these linear genic lines that are present
inside the vein represent the syn eye
or fine web-like changes that are present.
But there is residual material in the vein which has a
somewhat triangular shape in this case.
And again, what's striking is the irregularity
and undulating nature of it
and the angulation, again, this is not the smooth,
rounded structures that we expect
to see in in acute deep venous thrombosis,
but rather somewhat angulated triangular appearance
from scarring and retraction.
The artery is above here.
We can see the alias thing in the striking finding here is
in the vein, which has a blue lumen,
but you can see that the wall
of the vein is thickened on both sides in a very uniform
pattern around both the anterior
and posterior aspect of the vein indicating a
circumferential wall thickening.
Again, the result of prior recanalization analyzation,
Recanalization and process can also be done, can be seen
and also seen in part of retraction.
Here we can see the residual lumen forming around
the vein as well as around the edge of the vein.
Collateral veins can be seen when there's obstruction.
We typically see them in more chronic conditions
but can be seen in acute venous obstruction.
Here we can see a patient with chronic changes.
The vein is chronically occluded.
It's the small hypo coic structure
running through the image.
And we can see that there are venous structures lying on the
wall of the vein here, as well as venous structures
that are bypassing this obstruction above the vein here,

Lower Extremity Venous Protocol

when we look at our lower extremity protocol,
we wanna make sure that we have a complete of evaluation
and this includes evaluation of the common femoral vein,
including the saphenofemoral junction, the entire length
of the femoral vein, the central portion
of the deep femoral vein,
and the entire portion of the popliteal vein.
At the very least evaluation
of the calf should include any areas that are symptomatic
and many centers invo include the calf veins as well.
The calf veins are quite numerous.
And protocols for C veins can be quite simple from one view
of the posterior tibial
and perineal vein to multiple views
separately evaluating the posterior tibial perineal sole
and gastrectomy veins in both their medial
and lateral compartments.
Here are an image of the calf veins, the major calf veins,
the posterior tibial and the near field
and the perineals in the farfield as noted by their
normal structure and normal location
and the corresponding arteries traveling within them.

Evaluation of Calf Veins

The caffeines are becoming more and more important
and getting to be part
of people's understanding of deep venous thrombosis.
As our imaging gets better, our ability
to see these veins become easier.
And of course,
we can see that
this veins are the earliest part
of the clots that are present.
We know that from natural history,
but we also recognize that there are a marker for more
central disease appearing
and about 20% of patients who have c vein thrombosis
more central deep venous thrombosis will appear.
And so,
this is one
of the reasons why people are very interested in intervening
with papal with c vein thrombosis
before it gets to proximal deep venous thrombosis.
Proximal DVT is much more likely to produce
symptomatic pulmonary embolism,
and so it's a more severe disease than
isolated caffeine and thrombosis.
Additionally, some people are very interested in calf DVT
because of an increased risk of
chronic venous insufficiency
and the risk for future deep ven thrombosis.
And so the American College of Chest physicians
recommend treatment of symptomatic PHA thrombosis.
If patients are not treated for symptomatic PHA thrombosis
and it's identified, a followup ultrasound must be confirmed
to make sure that it is this patient is not one of the 20%
of patients who,
will have disease, which propagates,
As I've said before, about 17% of patients
who are symptomatic will have isolated calf vein thrombosis.
If you consider that about 20 to 25% of patients
who are sent to the lab have deep venous thrombosis,
about 4% of the patients who are symptomatic who come
to the lab will have isolated caffeine thrombus.
The American College of Chest Physicians again recommends
treatment and recognizing this,
the guidelines for the
various agencies have varied.
And so the A CR
and the A IUM guidelines, which are current state
that the patient presentation, clinical indication
or clinical management may require protocol judgment such
as detailed evaluation of the superficial system
or evaluation of the deep C veins
or a bilateral study, the ICVA,
which is the intertidal commission for the accreditation
of vascular labs in their recent guidelines includes
evaluation of the posterior tibial
and peroneal veins as part
of their guidelines for accreditation.
Here we can see that
there is
a C vein thrombus.
There's the caffeine on the left,
and with compression, the vein does not go away indicating
that there is a filling defect and
therefore acute venous thrombosis.
The problem of venous ultrasound
and caffeine is not one of specificity.
That is to say if you find a filling defect in the caffeine,
it is almost certainly acute venous thrombosis or scarring.
The issue with caffeine thrombosis is sensitivity
and depending on the study's performed, sensitivity may be
as low as 50% up to 85%
depending on the patient's clinical indication
and, their underlying conditions.
Now there's an imaging protocol
and then there is a DVT protocol
and the current I-C-A-V-L recommendations for protocol is
that every patient get common femoral vein
scanning bilaterally,
and the popliteal vein is studied in patients.
This is to look for respiratory variation
and other compression maneuvers such
as distal compression can also be performed.
Here we can see that the waveform is changing over time
slightly, and then when we compress on the calf distally,
we can see a strong augmentation from this.
And this augmentation is used by some people as a sign
that there's not obstruction between the point
of compression and the point of intonation.
A few other things about the spectral doppler.
If the doppler waveform reverses in the proximal veins,
that's not typically abnormal,
but if that reversal continues all the way down the leg
and here in the caffeines, there's still a bit of reversal,
you have to be concerned that the spectral doppler is overly
pulsatile, which may indicate right heart disease,
right heart failure or tricuspid regurgitation.

Indications for Lower Extremity Venous Ultrasound

Clear cut indications for lower extremity ultrasound
are in patients with a symptomatic leg
where DVT is expected.
We also scan patients
who are high risk in the hospital setting,
although this is controversial for some patients,
we do not typically recommend
a lower extremity venous ultrasound
to exclude pulmonary embolism since the absence of
A DVT does not exclude the disease.
However, it is used in some clinical pathways
if the patients have symptomatic legs and chest symptoms.
The presence of A DVT is effectively
a good surrogate for a imaging study of the chest,
which indicates pulmonary embolism for patients
with known DVT or pulmonary embolism.
Occasionally we will,
study patients,
but it, there needs to be a reason
for this study as it must change.
Clinical management clot in the leg,
even adequately treated clot in the leg may grow.
And so just the presence of enlargement of the clot
is not important in terms of treatment failure.
Treatment failure is defined by other processes such
as inability to maintain adequate anticoagulation,
which is blood tests or thromboembolic disease,
which occurs despite treatment.
Indications for lower extremity venous ultrasound vary
depending on the patient's clinical presentation
and management pathways,
but clearly patients with a symptomatic leg
or calf whom venous thrombosis is suspected,
should get a lower extremity venous ultrasound.
In some hospitals, high risk patients are also screened,
for venous thrombosis.
And this has been found with some groups such
as spinal cord patients and neurosurgery patients.
It is not usually indicated to exclude pulmonary embolism,
but a few words about this.
First of all, in a patient with a symptomatic leg
and chest symptoms, it may be prudent
or quicker to do a venous ultrasound study.
And if DVT is is found, the patient should be treated
and the presumption made that the chest symptoms are related
to pulmonary embolism in the presence of known DVT.
On the other hand, if the ultrasound studies are normal in a
patient with suspected deep venous thrombosis,
further evaluation is clearly warranted.
As many patients with pulmonary embolism will have normal
leg ultrasounds or normal venograms.
As a rule in patients with known deep venous thrombosis
or known pulmonary embolism,
lower extremity venous ultrasound
is not generally indicated,
but if there are reasons why
the study can change patient management,
it's could be considered.

Pitfalls and Considerations in Venous Ultrasound

When looking at venous ultrasound, we have to recognize
that the study is incredibly accurate,
for the central veins sensitivities
and specificities in excess of 95%.
But there are some pitfalls
and that we need to recognize there are certain veins
that are more difficult to compress than others.
Typically, the Femoral vein in the region
of hunter's canal can be somewhat difficult to compress
and some tricks are to compress from the front
and the back using your hand on one side
and the transducer in the other.
You may have to press a little bit harder at vein junctions
such as the saphenofemoral junction.
Sometimes using,
a curve array transducer
or even a sector transducer
to get more exacting compression can be helpful.
We need to also recognize
that duplicated veins are quite common,
the femoral vein being duplicated,
and so we need to recognize
that now when veins are duplicated,
they're not usually duplicated along their entire length,
but we do need to appreciate the fact that there are veins
that can be seen along part of the course.
And if there are prior studies
that indicate a duplicated vein
and that is not seen, you have to be worried
that the reason the duplicated vein is not seen on follow-up
is that there's a thrombus within it
and the c veins are just multiple numbers
and it they can be quite daunting to visualize so many veins
from the interpretive point of view, some thrombi
can be difficult to dis differentiate
from acute from chronic.
This really represents the vast minority of cases
as I think about 95% of venous studies
that are positive can be
distinguished from acute versus chronic.
One issue though is recurrent DVT
recurrent DVT is acute deep venous thrombosis
on top of chronic change.
And this can be a quite difficult study
to diagnose.
There are some clues,
however, one is that an old study is available
and there is a new thrombus in a location that was free
of thrombus previously.
The other may be that there was a small vein
or small residual scarring previously,
and now this has gotten larger.
In fact, some people measure the size of the residual vein,
and differences of two millimeters
have been described as being significant.
This may be quite difficult to match up an old
and a new study and that may not, not a reasonable,
approach for,
most laboratories.

Follow-up Studies and Ruling Out Disease

Some other questions since we know that,
patients can have a dynamic process that is
to say have thrombi that evolves
and becomes into the more proximal veins.
Can we rule out disease with just one study?
And, we need to be aware
of several factors.
If caffeine thrombosis can be identified
but not treated, we need to rule out
propagation of this thrombus.
And this can be done by doing a follow up every five
to seven days for two weeks.
And if there's no central thrombus,
then the patient needs no further follow up.
There are lots of people who do not study the calf, however,
and there's controversy in how to work these patients up.
A lot of work is being done on this including ultrasound
with combined with
other things such as D dimer tests, which is a blood test
and pretest probabilities.
One thing I can say from a variety
of the literature out there of the three studies, a negative
ultrasound, even one that does not include the calf,
a negative sensitive D dimer and a ne
and a low pretest probability.
If any two of these three are negative
or are not indicative of DVT, the workup can stop.
Another approach to using ultrasound is
to look at limited studies above the the calf
and doing two studies five to seven days apart.
And it's been shown in several studies of which
this study from the animals internal medicine is the most
well regarded, that two studies five
to seven days apart adequately exclude
deep venous thrombosis.
The risk of DVT in a group
that were normal on two separate occasions was 0.6%,
which is way safer than a single negative venogram.
And so this is a safer approach.
So we have two different approaches, two studies five
to seven days apart
and using combinations of D dimer, negative ultrasounds
and low pretest probability.
What if you just do one limited test
and don't look any further?
Assuming 20% of patients have DVT
and 20% of those have isolated calf clot, 4% have calf clot
that would be missed by this technique.
And if we assume 20% of those patients,
the calf clot will propagate about
less than 1% will develop proximal DVT.
And of those 1%, only four tenths
of 1% will develop pe.
So the underlying risk of patients who have
no caffeine studies are already unlikely
to have disease.

Unilateral vs Bilateral Studies

Another question that comes up frequently is,
does the study need to be performed on both legs
or is one leg adequate?
First, let me state that spectral doppler
of the common femoral vein should always be performed on
both sides, whether the patients are symptomatic in one
leg or both legs.
This is because symmetry is important
to diagnose iliac obstruction.
And since we don't usually compress the IAC veins,
the doppler becomes an important test to, to pre
to the presence of more proximal obstruction,
either in the iliac or the inferior unit cable level level.
As for looking at both legs,
let me just also say that if you think spectral doppler is
of important criteria
and bilaterally symmetrical doppler is an important criteria
for you, then this needs to be performed on both legs
even if the symptoms are on one leg for the most part.
However, the question of unilateral versus bilateral
comes down to what is the risk of an asymptomatic leg
harboring DVT.
And this has been looked at by several studies here
or two from both the vascular surgery
and the radiology literature.
And I bring your attention
to all these patients in the first rows have
unilateral symptoms.
And if we go to the far end here, we can see that the risk
of the patient having clot not in the symptomatic leg,
but on the asymptomatic leg is only 1%.
And so that's quite low from my point of view.
This does not justify routine evaluation
of the asymptomatic leg.
However, if we look at this data a bit more carefully,
we can see that there are some subgroups of patients
where the asymptomatic DVT
is a bit higher, that is 4% in the group
with malignancy, 5% in the group with joint surgery,
and 9% in the patients with hypercoagulable states.
And so there are subgroups of patients
who deserve bilateral studies even when one leg
is symptomatic.
And in patients with cancer, patients with joint surgery
and patients with hypercoagulable states,
we do bilateral studies even in patients
who have symptoms on one side.
We also study our trauma patients with
both legs because we feel
that this is a particularly high risk group.

Availability of Venous Ultrasound Services

The next interesting question is,
does venous ultrasound need to be available
24 hours a day, seven days a week?
And of course if you have ultrasound sonographers
or vascular technologists
or in-house all the time,
venous ultrasound should be performed when it's indicated.
But many institutions don't have this.
And so what can we do?
Well, at Jefferson,
we don't scan patients 24 hours a day, seven days a week.
There are patients who are seen off hours who wait
until the next day and either they wait
or they get treated with low molecular weight heparin
and wait for their imaging the following morning.
The patients who get scanned immediately are those patients
with a contraindication to anticoagulation,
which need the study soon after the test is ordered.
And so the contraindications have been worked out
by a subgroup of people, both ER physicians,
vascular medicine, vascular surgery,
and radiology physicians.
And the contraindications for anticoagulation are
as follows, heme positive stools,
ulcers less than six weeks, low hemoglobin,
central nervous system surgery,
closed head injury and strokes.
Patients other than this group generally wait until,
the morning for their studies.
Now, is this a safe procedure
to give low molecular weight heparin
and wait for confirmation?
This is from the emergency medicines literature
and these were patients who were,
not had imaging
after PM or on weekends,
and they studied 128 patients, of which,
some
of them had pulmonary embolism
and some of them had acute venous thrombosis.
And so that was 44 of their patients.
Of the 128 patients,
and neither in the group with DVT or PE
or the group without DVT
or PE were there any adverse effects from giving
anticoagulation with low molecular heparin.
So it's felt to be a safer approach to defer imaging
in patients with suspected deep venous thrombosis.

Chronic Venous Disease

I'd like to go and just talk a little bit now about chronic
venous disease, of which the most common condition is
varicose veins.
This has become increasingly of greater interest
because of the treatment options for varicose veins
that are becoming more widespread, namely
endovascular laser
or radiofrequency ablation of these varicose veins.
So varicose veins are veins that are dilated, get
and start to lose their function.
As we can see in this,
image, we can see
that in this varicose vein the valves are separated and
therefore reflux freely.
Where here in the perforating vein
where the steep veins the valves are are competent.
And so this is primary varicose veins.

Role of Valves in Venous Function

So valves are quite important
because if you were to have
a valveless venous system when you stood up,
all the blood would become one column
from the heart all the way to the leg,
and the pressure on the, the veins
and the from the hydrostatic column would cause the leg
to swell and all the blood would pool in your,
in your feet and you'd pass out.
So the valves break up the column of blood
and so that the pressure of the hydrostatic column only
exists between one valve and the next,
and there are many, many more valves in the calf.
So the this pressure is broken up into many,
many different tiny portions of blood columns.
The valves also control the direction of blood flow from
the deep system to the heart
and from the superficial system into the deep system so
that blood is pushed from the superficial into the deep
system and out the deep system pushed
and propagated by the calf pump muscle pump back
towards the heart.
Now we need to remember that valves when left
to their own devices will stay normally open.
So when we're looking for reflux, we need to prove
that the valve actually closes.
We need to create enough back pressure so
that the valve would normally close.
And then when we see abnormal retrograde flow
through the vein, that indicates reflux.
So we cannot just look at
the leg in supine position and determine whether
or not reflux is present.
Most varicosities that we see are related to
Our human nature of standing up and the valves
and the veins becoming distended without venous thrombosis.
There is a class of patients who have
valvular disease from prior DVT, the so-called post tic
patients in this case of acute D venous thrombosis.
We can see the echogenic thrombi filling the vein,
but you can see here the sinus
and the valve caused are subsumed by the DVT.
And even after this material resolves,
the veins are diseased and won't function normally.
So in evaluating patients with venous incompetence,
we not only wanna look for reflux,
but we want to look for the presence of
residual thickening or prior deep venous thrombosis
or scarring in the veins as a clue to the etiology
of the venous insufficiency.

Evaluating Patients for Chronic Venous Disease

In evaluating the patients for chronic venous disease,
we concentrate in particular on the saphenous veins,
both the great saphenous vein and the small saphenous vein,
but also want to evaluate any sites
of symptomatic varicosities,
which may be in the tribulations of the veins such as the
poster medial branch or the a**l lateral branch
or other branches of the saphenous vein.
Here in this image we can see the saphenofemoral junction
and the saphenous vein as it's coming down.
The saphenous vein may be varicose itself
or the varicosities may lie within the
tributaries of the vein.
When we look at the small saphenous vein, we wanna recognize
that this is the vein that runs through the calf
and typically terminates in the popal vein,
but there are lots of normal variants that are present,
including as we can see here in the upper right,
a thigh extension vein, which extends up
and often leads to the vein of Gini
with an intact sahan popliteal junction
or down here a thigh extension vein
with an absent sahan popliteal junction
or variance of that as seen here on the bottom left
of just a small,
sahan popliteal junction.

Evaluation for Venous Reflux

So how do we evaluate patients for reflux?
Well, most patients should be studied in the erect position,
15% reverse t trella berg is also reported,
but the standard is to have the patient standing
with a leg rail axed and not bearing weight.
We should never evaluate patients
for reflux in the supine position
as it can be false positive reflux.
And the standard is distal compression
with rapid release typically done by hand.
Some people also Val Salva
and this Val Salva maneuver is acceptable at the saop
femoral conjunction, but not distal to that.
What constitutes an abnormal amount of reflux?
Most people would say a reversal of flow
for greater than half of a second is evidence of reflux
and protocols can be quite variable,
but I think that you want
to evaluate both the great saphenous
and the small saphenous look for enlarged tributary veins,
particularly if they are varicose.
When you stand the patient up to look
for obvious perforators including,
perforators which are incompetent
and evaluate for the presence of of reflux.
Similarly,
or additionally, if you're going to ablate the patient,
you wanna evaluate the vein size
and the depth to see if it's appropriate for ablation.
This is an examination which is normal.
You can see the normal flow within the vein.
And then with Val Salva, there is a tiny blip
of reverse component and then no reverse flow at all.
And then with release of Val Salva, the flow continues.
Let's speak about this small reverse blip.
The veins take some time to close, so as the pressure builds
beyond the valve, the veins will leak a little bit
and then flow should stop.
And a small amount
of flow in the reverse direction is not indicative of
reflux, and that is why we require more than a half a second
of reflux and values less than that are not significant.

Conclusion

We've demonstrated the findings
of acute venous nerve disease scarring
and venous insufficiency.
Thank you for your attention.