Ultrasound Evaluation of Pediatric Abdominal Organ Transplant - HD

Introduction

Hello, my name is Harriet Paul Thiel,
and I'm from Boston Children's Hospital
and Harvard Medical School.
And I look forward to discussing ultrasound evaluation
of pediatric abdominal organ transplantation.
Ultrasound is critical in the early
and late post-transplant evaluation.
Pediatric postoperative anatomy
and potential complications are not identical
to those in adults.
Children are more susceptible to vascular complications
and renal transplants in children are more prone
to urological complications.
What I plan to do with you is
to review the ultrasound features
and common complications of pediatric renal, hepatic
and multivisceral transplants.

Pediatric Renal Transplantation

Kidney transplantation is a treatment of choice
for end stage renal disease, and both cadaveric
and living related donors are used
and a retroperitoneal surgical approach is
done by our surgical colleagues as in adults.
But the vascular anastomosis are dictated by the size
of the kidney and also of the child.
The arterial anastomosis can be to the distal aorta
and to the common or external iliac artery,
and the venous anastomosis can be to the vena cava.
The common iliac or external iliac vein
and the ureteral anastomosis is to the bladder,
although the orifice is higher than in the native bladder.
And you see here on the right a couple
of diagrams showing the anastomosis
and the bladder as well.

Baseline Ultrasound Examination

We perform a baseline ultrasound examination within the
first 24 to 48 hours after transplantation,
and we perform a full gray scale imaging examination
where we assess renal size
and echogenicity the status of the collecting system
and ureter, and we determine the size
and location of postoperative fluid collections.
As far as the Doppler examination is concerned, we look
for flow in the renal vessels
and as well as in the iliac vessels, aorta
or IVC and or IVC,
and we perform spectral analysis
to establish baseline velocities and waveform patterns.
And on this slide, we have the normal postoperative anatomy
of the kidney transplant.
You can see here's a portion of the kidney
and the main renal artery coming out off the aorta.
In this particular case with the anastomosis right here,
and we assess the spectral wave forms, we look
for a nice sharp upstroke of the
arterial waveform.
And we also do assess velocities as well.
Here we see
normal waveform within the intrarenal portion of the main,
renal artery,
and we also assess venous anatomy, the main renal vein,
as well as the iliac vein
or IVC depending on what anastomosis were performed.

Complications of Renal Transplantation

Complications of renal transplantation
can be vascular urologic.
There may be perinephric fluid collections.
There may be abnormalities of the renal parenchyma
and biopsy is also associated with complications.
Fortunately, the incidence
of vascular complications is really quite low,
and certainly with the living related donors
it's extremely low.
However, when they do occur,
there is often significant morbidity or even graft loss,
and it's really important to have timely intervention.
So the ultrasound examination becomes critically important.
And of course, the doppler evaluation as part of that
evaluation.

Vascular Complications

Renal artery stenosis usually occurs within the first three
months after transplantation
and accounts for about one to 5% of all cases
of post-transplant hypertension.
It usually occurs in patients
who have undergone end-to-end vascular anastomosis,
and a stricture may occur either at the anastomosis itself
or within the donor
or recipient artery with color
and spectral doppler.
There may be focal color doppler aliasing turbulence
and spectral broadening.
We often see very high peak systolic velocities
of greater than 200 centimeters per second
at the site of stenosis.
And or a ratio of stenotic
to pres stenotic segment velocity greater than two to one.
In some patients, downstream of the stenosis,
there may be a delayed systolic upstroke
and a dampening of the arterial waveform,
the so-called tardis parvis waveform.
And this can be, this, as I say, will be distal
to the stenosis and in,
and maybe seen within the intrarenal arteries as well.
If the patients are clinically well,
then these patients are generally monitored
and treated conservatively.
Here's one such patient with renal artery stenosis.
Here we see the at the site of anastomosis,
there's a lot of color aliasing,
and I would just mention in passing
that it's very important
to have the appropriate velocity settings
because if they're set too low, you may have a false sense
of a stenotic area if you just look with color and,
and you must assess this with spectral
waveform as well.
And here you can see that the velocity
in the iliac vessel is about 98 centimeters per second.
But distal to that within this region of color
aliasing, the velocity is very high.
It's you know, more than two
and a half meters per second.
And you'll notice that the wave form also is abnormal.
There's an exaggerated systolic peak
and diminished diastolic flow
and more distally within the
parenchyma of the kidney itself.
You see that there's a small somewhat delayed
systolic upstroke
of the so-called tardis parvus waveform.

Renal artery thrombosis, fortunately, is a rare event.
It occurs in less than 1%
of renal transplants,
and it tends to occur in the cadaveric grafts
and in the young donor kidneys,
and usually occurs in the early postoperative period,
meaning within the first month after surgery,
and unfortunately usually results in graft loss.
There are a variety of reasons as to why this occurs.
Surgical damage to the artery kinking of the vessel,
hyperacute or acute rejection, acute tubular necrosis
or hypercoagulability.
And there will be a complete absence of both arterial
and venous flow distal to thrombus
and in the intrarenal vessels.
And it's really important to adjust the technical factors
to avoid a false positive examination.
And power doppler may be useful in a technically difficult
patient because of its increased sensitivity compared
to the conventional color doppler.
So here's one patient with renal artery stenosis.
There's no flow within this graft at all,
although you can see that we do nicely display flow within
the vessels adjacent to the graft.
So this was a true case of renal artery thrombosis.

Renal vein thrombosis is rare, occurs in fewer than 4%
of transplant cases
and usually occurs within the first week after surgery.
Patients will present with pain
and decreased renal function.
And renal vein thrombosis also, unfortunately,
usually leads to graft loss.
Causes, again, problems with the anastomosis.
Patient dehydration, hypercoagulability
or propagation of ipsilateral femoral
or iliac deep venous thrombosis
or extrinsic compression of the renal vein
by a postoperative fluid collection.
There will be diminished
or absent flow in the main renal vein.
And a very important sign of renal vein thrombosis and
an early sign is an abnormal elevation
of the resistive index within the renal artery.
Here is one example of a patient with renal vein thrombosis.
The kidney is swollen.
There's decreased cortical medullary differentiation.
And you'll see in this patient there actually is some flow
within the main renal vein.
It may be a bit dampened, but it's still there.
And in some of these patients, the thrombosis
actually starts the thrombosis process begins peripherally.
And initially there may be preservation
of flow within the main renal vein.
And really the most striking abnormality is this flow
within the renal artery, which is highly abnormal.
You have a very prominent systolic peak
and reversal of diastolic flow.
This patient went on to have a CT of the kidney,
and as you can see, it's highly abnormal.
There's no minimal enhancement of the parenchyma,
really just in a subcapsular region.
There's very extensive clot within the renal vein.

Urological Complications

I'd like to move on now to a discussion
of the urological complications.
Most of these occur within the first month
after transplantation with urine leak
and ureteral obstruction being the most common.
Ureteral obstruction occurs in about 2% of cases,
often due to ischemia
because of the rather tenuous supply to the
distal ureter of the graft.
There may be edema at the anastomosis.
Other causes include infection,
extrinsic compression by a fluid collection
or kinking of the ureter.
By ultrasound, one can see a dilated collecting system of
and a dilated ureter,
and the site of your ureteral obstruction
may be visualized as well.
So here we see an example of a patient with a urine leak.
This is the inferior portion of the graft.
There's some dilation of the collecting system,
and then we see this koic fluid collection
surrounding the lower pole.
These patients tend to present with ascites
and increasing abdominal distension.
And ultimately this patient did go on
to have a percutaneous nephrostomy
and a diagnostic study, which showed a leak from the ureter.
This is a different patient with ureteral obstruction.
The ultrasound image of the graft shows dilation
of the collecting system
and a dilated tortuous ureter percutaneous
nephros gram again shows contrast in the collecting system in ureter,
which terminates in this bulbous tip.
And without free flow
of the contrast material into the bladder.
Patient patients can
develop urinary tract infections as either an early
or a delayed complication of transplantation.
And in children pyelonephritis is
relatively common in comparison
to adult transplant recipients.
And there are also increased rates of
sico ureteral reflux in children compared to adults.
So here's one patient with pyelonephritis.
We see the kidney
and mild to moderate dilation of the collecting system.
This patient went on to have a radionuclide cystogram,
which we see here on the right.
Here's the bladder, and you can appreciate the reflux
of the radiopharmaceutical into the somewhat dilated
ureter and collecting system.

Perinephric Fluid Collections

Perinephric fluid collections are very common in the early
post-transplant period, up to about 50% of cases.
These collections may be hematoma
or lymphocy or urine or
or may be due to an abscess.
The ultrasound findings are not specific
and to make a specific diagnosis
fluid aspiration and analysis is required.
However, the timing of the development
of the fluid collection can suggest the etiology
with hematoma and neuron
generally occurring in the immediate postoperative period,
whereas a lymphocy usually
has its onset after about four to eight weeks.
Here is one example of a hematoma.
We have the graft,
and in the pelvis we see this somewhat dumbbell shaped fluid
collection with echogenic linear strands.
This was a hematoma
and ultrasound of course can be used not only
for diagnostic purposes, but also to guide drainage.
We see here an image taken
after placement of a pigtail catheter into the collection.
Here is a fluoroscopic image of the tube.
This is a patient who had a lymphocy.
They're generally anti koic,
but they can com contain
proteinaceous debris.
They can hemorrhage as well.
And here we see it on a
a CT scan adjacent to the graft.

Parenchymal Abnormalities

Parenchymal abnormalities can occur.
Diffuse parenchymal disease may lead to graft dysfunction,
and acute acute tubular necrosis rejection
and drug nephrotoxicity are all potential
diffuse parenchymal disorders.
These are difficult to differentiate by imaging alone.
Ultrasound is neither sensitive
nor specific for diagnosis.
Although ultrasound is helpful to exclude other causes
of graft dysfunction
and a core needle biopsy is generally
necessary for diagnosis.
Focal processes of course
can affect the parenchyma of the graft.
And there are many different things that can occur.
Focal cysts an abscess, a focal infarcted tumor
and a focal process may not lead to graft dysfunction.
Here's one patient with drug toxicity.
We see the graft.
There's somewhat diminished
cortico medullary differentiation.
The Doppler ultrasound evaluation
of the arterial blood flow is abnormal,
but it's a non-specific finding.
We just see that there's
very prominent systolic peak
and markedly diminished diastolic flow.
This is a different patient with acute rejection.
Again, we have a swollen graft.
In particular, I would draw your attention
to the endothelium, which is thickened here,
and this is a sagittal view of the upper part
of the bladder, which is filled with a small amount
of urine, and then the markedly thickened ureter,
especially distally.
At the ureter neo cystostomy site, we see
that there is also urothelial thickening in this patient
with acute rejection.

Biopsy Complications

Biopsy is performed in the graft for a variety of reasons
and is associated with its own complications.
The most important being arterial venous fistula
and pseudo aneurysm.
These occur in anywhere between one
and 8% of transplant biopsies.
A fistula will develop when both the arterial
and the venous walls are injured by the biopsy needle.
And a very large fistula may cause ischemia
to the renal parenchyma due to a steel phenomenon.
By ultrasound, we will see a focal area
of turbulent flow and aliasing with color doppler.
And there will be very high velocity flow with low
resistance in the feeding artery
and arterial of flow in the draining vein.
Interestingly, the majority
of these fistulas will resolve spontaneously in about one
to two years time.
Here's an example of a fistula.
We see the graft, which looks pretty benign,
but when we turn on the color, you see this very marked
abnormality, very abnormal flow pattern,
and then this tissue vibration artifact.
And when we analyze the spectral waveform,
you'll notice that the arterial signal is very very
fast more than five meters per second,
actually 5.52.
When you listen to this in real time, it has a very
harsh sound,
and this is an arterialized waveform.
Again, when you listen to it in real time, you hear
that it is it's a venous vessel,
but it has an it's arterialized due to the presence
of the shunting through the fistula.
Pseudo aneurysms are created
when an arterial wall is injured by a biopsy needle,
and these aneurysms have a cystic appearance
by gray scale ultrasound.
When they are evaluated with color doppler,
they will display a turbulent, a swirling flow pattern.
Sometimes it has the so-called yin yang appearance.
A very large pseudo aneurysm is at risk for rupture,
and occasionally transcatheter embolization may be required.
Here is a patient
and where we see the graft,
and then we have these peripheral cystic areas,
and you could you can see why they might be
initially thought to represent pyramids,
but they don't really have a parametal shape.
And when you look with color, you see the very abnormal
vascular pattern.
And when you interrogate one of them here for
instance, you have a very
peculiar abnormal flow pattern.
Here's another one, but certainly not a normal arterial
or venous waveform.

Pediatric Liver Transplantation

I'd like now to move on to a discussion
of pediatric liver transplantation, which is the treatment
of choice for end stage liver disease.
And there are a variety of possibilities when it comes
to liver transplants in the larger children.
If a whole liver is available a whole liver graft can
be placed into the abdomen.
And the IVC
anastomosis will occur above
the liver and below the the liver.
The whole graft will contain both supra intra
and infra hepatic portions of the IVC
and the recipients IVC will be resected,
and the donor IVC will be used as a replacement.
And then here you see the lower anastomosis
and there'll be endocyte anastomosis
of the portal vein and the common bile duct.
And the donor common hepatic artery
will be anastomosis end to end,
or an side with the recipient,
common hepatic artery.
We often will come
or be asked to evaluate a reduced sized transplants
or split livers or living donor transplants.
And these are performed
because there is a an organ shortage,
and there are often problems
with donor recipient sized discrepancy.
This diagram shows a liver split into two portions.
The ENO segments are seen here.
And in these patients,
the recipient IVC is left intact.
And there is a confluence of the hepatic veins in the recipient are formed into a
cuff, and they are then anastomosis
with the donor hepatic vein
or veins using a so-called piggyback technique.
The graft can also contain a portion
of donor intrahepatic IVC, which is blind ending inferiorly In my hospital.

Baseline Ultrasound Examination for Liver Transplants

We perform a baseline study within the first 12 hours
of transplantation,
and every 24 hours thereafter,
while the patient is in intensive care
we subsequently will follow up
with weekly ultrasound evaluations while the patient remains
in hospital or more frequently.
Essentially whenever clinically indicated.
If a vascular problem is suspected,
we will supplement the ultrasound examination with CT angiography.
MRI and MR Cholangio Pancreat topography are generally
reserved for biliary complications,
and we use ultrasound as a guidance tool
for interventional procedures.
So here is an example of a whole liver graft,
and I include this image just to point out
that in the immediate postoperative period
it is completely expected that there will be
edema of the liver
and which is manifested as very prominent portal
portal areas.
It has a somewhat starry sky appearance
and that that appearance should resolve over
the next week or two.
These color doppler images are from a different patient,
and essentially the arterial and venous wave forms
and anatomy are very similar to those
that you would expect in a native liver.
So here we see a hepatic vein coming into the
IVC and here we have antegrade flow into the portal vein.
And here is the left hepatic venous waveform,
hepatic arterial waveform with good systolic upstroke
and diastolic flow.
And here is some normal spectral
waveform pattern within the inferior vein cava.
Again with the split liver transplants
and the living related donors
and reduced size transplants, the anatomy is often
much more complicated and variable.
There's a rotation usually of the hepatic segments, so you
you really need to spend some time to orient yourself.
And also, I would just wanna emphasize that it's
so important to speak with the surgeon
or at least to have a diagram of
what the surgical anatomy was at the time of surgery,
because that will save you a lot of grief later on
and will help you in terms of knowing what anastomosis
you are trying to evaluate.
So here is a a left a left
hepatic lobe graft.
And we see the portal vein here, somewhat
slightly pulsatile flow,
but antegrade flow the hepatic artery
and hepatic ugal flow within the hepatic vein.
I'd like to make another comment
and that is that although it's really important to try
to search out the anastomosis,
and that really is our goal very often in the immediate postoperative period,
they may be very difficult to access
because there's often a lot of bowel gas,
the patients may be positioned awkwardly.
There are usually a lot of overlying bandages.
So we try to use whatever window we can.
And if we can't image the anastomosis,
then we pay a great deal of attention to the quality
of the waveforms too,
which can give clues about upstream abnormalities.

Causes of Liver Graft Dysfunction

Causes of liver graft dysfunction include vascular stenosis
and thrombosis, biliary complications and rejection.
Hepatic artery patency is vital for long-term graft survival
and is the sole blood supply
to the biliary epithelium of the graft.
It's very common to
encounter postoperative edema at the anastomosis in the
first 72 hours following transplantation
and stenosis have been reported
as occurring in up to about 14%
of pediatric graft recipients.
It is believed
to be the most common vascular complication most frequently
occurring at the anastomosis,
although it can occur more distally
and risk factors include trauma at the time of surgery
and severe rejection.
Ultrasound features include an increased velocity,
generally greater than two meters per second at
the stenotic site.
Although, as I've mentioned, the site
of narrowing may be difficult to identify.
And for that reason,
you may often end up relying more on abnormal arterial waveforms distal to the stenosis.
And as you've seen already in the kidney transplants
we will often encounter a tus parvis waveform
with a decreased resistive index
and a prolonged acceleration time distal to an arterial stenosis
with turbulent flow distally as well.
So here we see proximally near the anastomosis,
a pretty normal looking arterial waveform,
but as we proceed more distally into the liver
we see on the right a pretty dampened arterial waveform rounded
and an abnormal arterial waveform in the left
hepatic artery as well.

Hepatic Artery Thrombosis

Hepatic artery thrombosis also is relatively rare,
but still occurs in about 5% of the whole liver grafts
and a slightly higher incidence of about 7.2% in split
or living related donor grafts.
When there's a complete arterial occlusion
parenchymal infarction with necrosis
of bile duct epithelium ensues there will be an absence of flow in the main hepatic artery
and the tardis parvis pattern will be identified
in more distal branches.
And they're presumably being supplied
by collateral vessels that develop CT
or MRI are often necessary for confirmation
of the diagnosis of thrombosis.
These patients sometimes are taken immediately
to surgery in the hopes of perhaps removing the clot.
Sometimes angiography is performed
as part of fibrinolytic endovascular therapy.
So here's one patient on the day
of transplantation, had a study.
We see the hepatic artery here in the hilum
with a relatively normal wave form.
But more distally within the liver.
We see that the arterial waveform really
looks quite different.
It's somewhat dampened
and it has increased diastolic flow
implying that it may be very dilated distal to
a site of obstruction.
Also note that these additional arterial branches show very
abnormal arterial flow.
One day later you see
that the arterial wave forms are barely detectable.
This patient went on to have an emergency CTA,
and you can see that already there's been some
damage to the graft.
We have these geographic zones
of diminished parenchymal enhancement
and the main hepatic artery within the
hilum
and more distally within the liver is completely occluded.

Portal Vein Complications

Portal vein stenosis is uncommon
and usually occurs at the anastomosis.
Patients may be completely asymptomatic
or they may have symptoms of portal hypertension.
Portal vein stenosis tends
to occur more often in reduced size grafts
because of a limited length of donor portal vein.
And various parameters are used
to make the diagnosis.
There may be more than 50% reduction of vessel lumen
or an absolute vessel diameter less than
or equal to 2.5 millimeters.
As with arterial stenosis with the venous stenosis,
there may be focal color aliasing right at the
site of narrowing.
The velocity in the stenotic segment tends to be
much higher than in the pre stenotic segment,
at least three to four times higher.
And there's often a post stenotic jet
with a velocity somewhere in the range of one
to three meters per second.
So here's a patient with a reduced size graft,
and you'll notice here is the portal vein,
and right at the anastomosis, it's very very narrow.
This is a different patient,
but you can see again, mark narrowing
and there's some aliasing.
And then the spoke post stenotic jet well documented with the color.
And the velocity also is about
four times higher in the post anastomotic region.
Compared to just prior to the anastomosis, this patient went on to have
an angiographic procedure
where you can see before and
after where the stenotic area was significantly enlarged.

Portal vein thrombosis again,
occurs most often in reduced size transplant
and commonly involves the extra hepatic segment.
Risk factors include decreased portal venous inflow.
This is often the a problem in patients
who have many portal systemic shunts,
and there's just not a lot of flow going through the
through the portal vein.
Prior splenectomy is also a risk factor
and excessive vessel redundancy,
and also the use of venous conduits
usually cryopreserved iliac veins.
They are also associated
with increased risk of thrombosis.
Symptomatic cases are treated with thrombolysis
or surgery either thrombectomy
or placement of a venous graft.
By ultrasound, we see a narrowing of the portal vein
and there's often echogenic intraluminal thrombus
with no flow.
Acute thrombus, maybe koic or maybe partial
and reverse portal flow
may be seen in the intra hepatic vessels due to the presence
of arterial portal shunting.
So here we have a patient
with a reduced size graft.
You see that there is some periportal edema.
We can see the hepatic vein here in color
and the spectral waveform,
which is in the appropriate direction.
The hepatic artery, again, appropriate flow into the liver
and a relatively normal wave form,
but the portal venous flow is very abnormal.
We see reversal
of flow in the intrahepatic portions of the portal vein.
We see it down just to the hilum,
but we really do not appreciate the extra hepatic portal vein.
So here you see a reversed wave form
and this patient went on to have a CTA and we see a very large spleen with a lot of port
of systemic collaterals.
And we really cannot appreciate the extra hepatic portal.

IVC and Hepatic Vein Complications

Vein stenosis
and thrombosis of the IVC are relatively rare
occurring in less than 1% of transplant recipients.
These do tend
to occur more often in children than in adults,
and also in patients who have had more than one transplant.
The stenosis may occur due to a discrepancy in the size of the donor
and recipient vessels
or there may be spr caval kinking
from rotation of the organ.
Delayed stenosis may occur as a result of fibrosis,
chronic thrombosis or neointimal hyperplasia.
Ultrasound findings include a reduced caliber at the
anastomotic site, a velocity in the stenotic segment
that is three to four times greater than in
the pre stenotic segment.
Color doppler aliasing,
and an absence of the usual flow ity that we
expect to see in the vena cava.
Sup caval stenosis may cause a reverse flow
or absent ity in the hepatic veins.
IVC
and hepatic vein stenosis may present
as a Bud Chiari syndrome.
IVC thrombosis can occur at the level
of the superior and inferior anastomosis
in whole liver grafts.
And color doppler shows vessel narrowing
or intraluminal echogenic thrombus with no doppler signal.
And these stenotic vessels can be treated
with balloon angioplasty
and stent placement in this patient.
We can see the IVC on the gray scale image when
we look with color.
You'll notice that
the flow within the IVC given the interrogation angle, is actually going in the wrong direction.
It should be flowing towards the transducer
and it's actually flowing away.
And we see this somewhat dampened venous waveform.
On this image, we see that there's actual thrombus within the intrahepatic portion of the IVC,
and there's a vessel that's posterior
to the liver, an aus vessel,
which has enlarged and now contains flow
and is taking up the the flow
that should have been carried
by the vena caba in this patient with IVC thrombosis.

Biliary Complications

I'd like to move on now to a discussion
of biliary complications.
These are the most comple most common complications
after pediatric liver transplantation.
There may be a leak of B
or so-called myeloma that may be related to the anastomosis
or maybe non anastomotic in origin.
There may be stenosis of the bile duct with associated dilation
and there may be intrahepatic bile stone sludge
or debris leaks at the biliary anastomosis are
associated with very high morbidity
and occasionally mortality.
When there is a T tube in place,
the leak occurs at the site of T tube entry into the duct.
Non anastomotic leaks are associated
with hepatic artery thrombosis.
In most cases, the bile can extravasate into the peritoneal cavity
or it may form a peri hepatic collection.
A small leak may close spontaneously,
however, in other cases, surgical revision
of the anastomosis may be required
and bile collections can be drained percutaneously.
Here's one patient who developed a leak at the site
of TTU insertion.
We can appreciate this fluid collection adjacent to the graft.
And you can see that there's a dilated tubular
avascular structure within the liver corresponding
to dilated bile duct.
And here we see again the dilated tubular
duct and the large bile collection.
And here we see the leak at the site of the
ttu insertion.

Strictures can also occur at the anastomosis
or maybe non anastomotic.
The anastomotic strictures are usually due
to scar tissue and they may cause retraction
and narrowing of the common bile duct at the suture stite.
Non anastomotic strictures are caused
by bile duct ischemia secondary to arterial insufficiency.
So again, another complication of arterial thrombosis.
So here's a patient with a biliary anastomotic stricture.
We see too many tubes within the liver on the
gray scale images.
This is a vessel
and this is dilated common bile duct
and intrahepatic ducts.
And these findings are confirmed
by Mr.
cholangiography here on the bottom row.

Rejection in Liver Transplants

Rejection is an important cause of graft loss.
There are no specific imaging findings associated
with rejection, but as with the kidney,
imaging does aid in ruling out other abnormalities,
and the diagnosis is only established histologically
by percutaneous liver biopsy.

Multivisceral Transplantation

I'd like to say a few words about
multivisceral transplantation.
There are only a few centers that are doing this procedure
in children, and my hospital is one of them.
They were initially performed in children who had
associated or who had simultaneous intestinal
and hepatic failure, usually related to TPN cholestasis,
so children with short bowel syndrome or pseudo obstruction.
But more recently, it has been used successfully
as a treatment, albeit a drastic one of primary abdominal tumors that involve the liver
or the root of the mesentery that
are refractory to conventional treatment.
This is a diagram that illustrates the operative procedure, the stomach,
the duodenum, and the pancreas.
The small bowel, the liver,
and the spleen are all removed from the donor.
The right colon may or may not also be removed.
And the corresponding recipient organs are also removed
and the donor organs are transferred on
block to the recipient.
The vascular anastomosis are really determined on a case
by case basis, but amazingly a common
scenario, we will leave the recipient aorta and IVC intact,
and there's only a single aorta to aorta
and a single CVA to cava piggyback
or cava to hepatic vein anastomosis.
So only two vascular anastomosis.
After this very really
sort of heroic procedure is done.
The ultrasound imaging of the abdomen
and graft anastomosis is performed daily in the immediate
postoperative period.
And once again, a complete knowledge
of the surgical anatomy is truly c critical to the success
of the examination
and the correct identification
of complications when they do occur.
Probably the most critical vessel to evaluate is the infrarenal abdominal aorta.
And when the aortic anastomosis is not visualized color
and spectral doppler analysis
of the hepatic arterial supply can provide evidence
of upstream disease.
As is the case with liver and kidney transplants.
When it's difficult to visualize the anastomosis,
the evaluation of the venous blood flow
and venous anastomosis is the same as
with hepatic transplants.
And a four quadrant evaluation
of the bowel is also necessary.
Here are some images of the aortic anastomosis.
We see the recipient aorta
and then the donor aorta here.
Here we see it again with color
and also on the sagittal CTA, the recipient
and the donor aorta here, anastomosis at this point.
Cable anastomosis, as I mentioned,
often a piggyback procedure.
So here is the donor IVC, it's sewn off
inferiorly and piggybacked onto the na of the recipients
of vena cava at this point.
And here we can see the kidney
and attached to the vena cava.
The ultrasound features
of the vessel abnormalities,
postoperative fluid collections are similar to those
of the renal
and hepatic transplants that I I've already discussed.

Bowel Disease in Multivisceral Transplants

Bowel disease is very common.
There may be rejection, ischemia, infection,
or mechanical dysfunction.
The ultrasound features of the bowel disease are
often non-specific.
There may be diffuse mineral thickening dilation and
or hyperemia and sclerosis.
Entoritis is a long-term complication.
Here we just see one example
of thick walled bowel with ultrasound.
And there's also some thickening
and a mild enhancement of the bowel
by CT PTLD.

PTLD

This is a heterogeneous group of disorders characterized
by monoclonal or polyclonal lymphoid proliferation
in immunosuppressed patients
after solid organ transplantation.
And it occurs in anywhere from one to 30% of children,
depending on the organ.
And the immunosuppressive regimen that is used compared to
an overall much lower incidence in adults.
PTLD is usually of B-cell origin
and of non-Hodgkin type.
Some cases are cell in origin
and up to 95 per percent of cases in children are associated with the Epstein bar virus.
So PTLD usually occurs within the first year
after transplantation in children
who are EB vs negative at the time of transplant.
And who receive EBV positive grafts.
PTLD can occur at any time after transplantation,
and there's really a variable appearance depending on the
sites of involvement, which may be nodal or extra nodal.
So here we have kidney transplant,
and you can see on these two gray scale images
that there's several solid hypo coic nodules
that are well shown on this.
Coronal reformatted image in this patient with PTLD infection is another,
common problem.
It's always a potential threat
because of chronic immunosuppression.
Infected postoperative collections are readily detected
by ultrasound and may be amenable
to ultrasound guided drainage.
Opportunistic infections are always a potential
long-term consequence, in particular, fungal disease.
Abdominal ultrasound can be useful in detection of hepatic
and splenic fungal disease.
For example, micro abscesses can be shown
as we see here, although there often not
demonstrated by ultrasound.
And if there's strong clinical suspicion, patients may need
to go on to have MRI examination.
Some places do ct.

Summary

In summary, imaging plays a vital role in the postoperative
care of transplant recipients.
Ultrasound with doppler is the imaging tool of choice
for the initial screening of vascular
and parenchymal lesions.
And familiarity with the ultrasound features
of transplant dysfunction will permit prompt diagnosis
and treatment of complications.
Thank you.