Ultrasound of Neonatal Abdominal Emergencies - HD

Introduction

Hi, I'm Dorothy Bliss,
a pediatric radiologist at
Children's National Medical Center.
Today I'm gonna be talking about the ultrasound imaging
of the neonatal abdominal emergencies.

Objectives

The objectives of this talk include reviewing the uses
of ultrasound in the evaluation
of acute neonatal bowel pathology.
We'll discuss the advantages as well as the limitations
of ultrasound and the assessment
of abdominal pathology in the neonate.

Advantages of Ultrasound

Ultrasound is a powerful tool in the
evaluation of the GI tract.
In children, of course, there's no radiation involved.
It's inexpensive, there's no sedation.
It exquisitely delineates mural layers
with a high resolution transducers
and in addition, it can assess both the vascular
and dynamic properties of the bowel.

Equipment Needed

We do need high resolution linear transducers
to be successful in evaluating the bowel.
These can be as high as 10 to 17 megahertz.
They can be convex vector sector probes.
We want high quality doppler capability
with a high frame rate, low flow velocity
sensitivity, extended fetal view.
Color doppler imaging all can help assess the bowel.

Reference Resource

This is a shout out to a free access site,
the World Journal of Radiology.
There's a nice article on abdominal ultrasound
of the pediatric GI tract that is available.

Bowel Layers

Notice the five layers of bowel.
Here we have the echogenic mucosal interface
with a hypo coic mucosa, the echogenic
submucosa, the muscularis, and then the ci.

Applications in Neonatal Abdominal Emergencies

Necrotizing Enterocolitis

We can look at bowel to assess
for necrotizing enterocolitis, myco meconium, plug,
even malrotation.
And of course it's very useful in the assessment
of abdominal cysts and tumors.

The pathogenesis
of necrotizing enterocolitis is still not quite worked out,
but we know that hypoxia ischemia as well
as bacterial invasion, all can involve
to result in necrotizing enterocolitis.
Prematurity is the most common risk factor,
but earlier hyper molar feeding
in the term infant heart disease.
Hirsch Sprungs can also put an infant at risk for this.
Umbilical artery catheterizations
with thrombi have also been associated
with a higher incidence of necrotizing enterocolitis.

The ileum and colon are the most common sites.
Hemorrhagic necrosis can develop
me submucosal subserosal gas bubbles can form.
And finally, full thickness necrosis
and perforation can develop.

Radiographic findings can be fairly non-specific.
You may simply see a gaseous abdomen
or some dilated loops with separation
that are somewhat tubular.
More specific findings include pneumatosis and portal.
Venus Gas at times somewhat difficult to visualize,
particularly if there's a lot of dilated bowel
or some residual stool.
Free air can be quite obvious as in this case,
or fairly subtle and not well visualized on a supine film.
If you are not looking for it carefully.

Ultrasound can be a very useful, modality in trying
to look for both early and late findings.
One can see bowel wall thickening hyperemia.
One can actually doppler vessels.
The superior mesenteric artery,
normally should have antiquated flow in diastole when there
is severe ischemia to the bowel,
one can actually see reversal of diastolic flow
or even absent flow in the mesenteric artery.

Late findings include portal venous gas.
Radiographically we'll see the tracking
along the liver by ultrasound.
The appearance can be very striking
and sometimes not even realize.
What you're actually are seeing are ear bubbles
that are tracking throughout the liver parenchyma.
As you can see in these two images,
when looking at the portal vein as you intonate,
you may actually hear these flex of bubbles coursing
through the portal vein and you can see them
as these little spikes
and you can hear them as well.
Here's an example where you can actually see the bubbles
coursing through the portal vein.
And again, you can see in the periphery the
liver parenchyma heterogeneous
because of the ear bubbles as well
with power doppler.
What can also identify the bubbles passing through
that portal vein.

Late findings also include pneumatosis.
We look for air bubbles within the wall
on radiographs by ultrasound.
This can also be visualized within the wall
as foci increased genicity.
At times it may be difficult to decide whether something
that's an air bubble is intraluminal or within the wall.
With, real time you can actually see the bubbles
that are intraluminal moving while those
that are within the wall staying in the wall of the surface
of the bowel loops.

We can also see a combination of
bubbles within the wall thickening, decreased peristalsis
of the of the bowel.
So here we have some evidence
of abnormally dilated thickened wall bowel
with decreased peristalsis and ileus.
You can look for potential reasons
for the necrotizing enterocolitis
and this includes thrombi within the aorta.
And since many of our
very premature infants have a booklet, artery catheters,
make sure you do take a look at the aorta.
We can look for secondary,
abnormalities if perforation has occurred.
Ated food collections may not be recognized on your
abdominal films, but can be nicely visualized by ultrasound.
Here we see a small ated collection along the liver.
Post perforation here
is a larger collection.
Eventually, as the perforation seals off,
you can start getting calcification of the cysts.

Malrotation

We'll move on now to another big concern
of ours in the newborn, population
or in the first month of life.
And that's ous from malrotation.
So the presentation is primarily ous vomiting.
The majority of children
with malrotation will present within the first
three to four weeks of life.
We hope to catch this diagnosis before bloody stool occurs.
And there's, irreversible necrosis of bowel.
This is a true surgical emergency.

So classically we look for malrotation
with your upper GI series looking for that, the,
abnormal limb position, duodenal genal junction,
and a potential VUIs.
As we see in this scenario.
By ultrasound, we sometimes can see the secondary signs
of a distended duodenum
and we've noticed that the superior mesenteric artery
and vein, normally the vein should be to the right of the
sic artery with it can be reversed.
This could be, again, an indirect sign
that the infant has mild rotation.
We can see this in patients with hetero taxii.
Here again, we have an aorta.
The SMA is to the left of the SMV.
We can see signs if there's an actual ulus
of the whirlpool sign, where with color dopper, you can see
how the vessel is,
the veins are surrounding the superior mesenteric artery.

It's important to remember however that the
S-M-A-S-M-V inversion is not a hundred percent
sensitive nor specific.
And since this is a true surgical emergency,
if one is truly concerned about MA rotation in upper GI
series is still considered the gold standard.
However, there are are some intriguing articles
that have been published suggesting
that ultrasound might be actually
more sensitive and specific.
The position of the do trigenal junction may be,
again, anterior to the superior mesenteric artery
and may be better visualized by ultrasound.
Again, since this is a true surgical emergency,
it probably behooves us
to do not just an ultrasound, but an upper gi.
If we are suspicious of ma rotation,

Meconium Ileus

meconium ileus is another diagnosis we should consider in
the vomiting infant in this scenario, typically associated
with cystic fibrosis, you have very thick tenacious
meconium stuck in dilated loops of ileum
because there's not much progression into the colon.
The colon tends to be quite small.
We label it the micro choline.
Here we see, at surgery markedly distended loops of,
ileum that are filled with thick meconium
and those very small colon by ultrasound.
What can see this echogenic meconium in dilated
loops of small bowel.
This is from a paper
by EC etal talking about neonatal bowel
by ultrasound assessment.
And we see a micro coline adjacent
to dilated loops of small bowel.
Here's a case that I had recently where you see a MicroCon
by the contrast enema
and markedly dilated loops of small bowel.
By ultrasound we can see again a very small colon
adjacent to markedly distended loops
of small bowel filled with meconium.
So ultrasound can very directly
demonstrate micro coline as well.
Here's another case where again you see the micro coline
with some dilated ileum filled with meconium
fare and her article also talked about being able
to look at normal sized colon
and making the diagnosis of meconium plug.
That's quite different looking in appearance on ultrasound
from meconium ileus.

Anal Atresia

Another issue that we deal
with in the newborn population is a**l atresia.
And one question is whether there's a high
or low, a**l rectal abnormality.
If it's a high obstruction, the rectum ends
above the elevator sling that's highly associated
with other anomalies and may require an ostomy
before they do a primary pull through
with a low a**l rectal anomaly.
The rectum occur, ends below the sling
and immediate pull through surgery might
be able to be performed.
Both of these have associations with spine anomalies,
perinos triad, sacral anomalies.
Some papers have suggested using ultrasound
to determine whether it's a high
or low, rectal, end.
And you can use this via a supra pubic perineal
or infra al approach.

Timing is an issue.
If you do the study too early, the distance
between the anus
and the end of the rectum may be falsely elongated
and suggest that it's a high,
a high lesion rather than a low lesion.
So there are some, recommendations to wait
until at least a day of age
before doing either an ultrasound or x-rays.

Here we have an imperforate anus measuring approximately
eight millimeters, suggesting this is a low lesion.
I think an important useful tool for ultrasound is
to identify if there is an accompanying fistula.
When urine mixes with meconium, it can calcify so
by ultrasound, if you see these echogenic foci within the
dilated rectum, this could, this is suggests
that there is indeed a fistula associated
with the a**l reia.

Hypertrophic Pyloric Stenosis

We'll move now on to hypertrophic piic stenosis.
Now this is not something
that occurs in the first day of life.
It is most commonly associated, in males
commonly the first born and we start seeing it as early
as two weeks, but more commonly between one
and three months of age.

We can see on these images that the mucosal,
the muscularis gets thickened, over time
and we can indirectly look at this using upper GI series.
Presentation includes non-bill vomiting
with the infant becoming dehydrated and alkali.
By exam, one might palpate an olive
on abdominal radiographs.
These are not particularly helpful
because you can have a crying baby
with a large descended stomach without a stenosis
or you could have an infant with RO stenosis who's vomiting.
So we don't recommend doing abdominal films
to help make this diagnosis.

In the old days, upper GI used to be performed
and you would look for secondary signs of obstruction
with a string sign, shoulder sign suggesting
that there is type pelar stenosis with,
hypertrophied muscle.

I When ultrasound, was dealt for pelar stenosis,
this really was an ideal exam
because it directly looked at the muscle
and at this point in time,
most centers use three millimeters as a cutoff
of theoric muscle.
The channel length can also be elongated
and various centers used 14, 15 to 17 millimeters
as their cutoff lens.
Secondary signs may not be completely useful
because you'll see little passage of gastric contents both
with pylos spasm and pyloric stenosis.

It is important to remember that,
the thickening develops over several days.
So if you have a premature infant
or catching it early,
the muscle may be somewhat thinner than a few days later.
And as important as you do the exam to image over time,
to differentiate pilo
or spasm, which is transient versus a true pilo stenosis.

So here we have an example of a longitudinal image
of the pori, very similar to this drawing.
Here you see the pyloric channel
with thickened muscle on both sides
in the transverse plane that most easily will
give you the true measurement of the muscle.
It should measure greater than three millimeters
to be considered abnormal.

Here we have another example of both the transverse
and loin planes,
both demonstrating a nice thick muscle on the transverse
plane as well as the elongated channel.

And here a last example,
it's useful to do the tra, do the actual measurements
of the thickness of the muscle in the transverse plane,
and make sure that when you are looking at the longitudinal
plane that the muscle is relatively symmetric, both
at the anterior posterior aspects.

And here a last example,
beware the early pori stenosis.
This was a three week old where the pori muscle measured
not quite 2.5 millimeters.
It was also borderline in its length.
In these cases it may,
if the surgeon is uncomfortable calling this a true pric
stenosis, just getting a follow up a few days later can
demonstrate rapid further thickening of the pylori pylorus.

Another problem is to make sure
that you are actually measuring the pylori itself.
This was an error in that the stenographer was measuring
what she thought was the pyrus,
which measured less than two three millimeters
and it also looked like it was not that elongated.
However, notice that we're quite high up
and this is the stomach.
But this is not the ris actually,
it's actually the GE junction that can be a mimicker
of lyrics.
This patient actually did have a pyro stenosis when we
properly looked at the ris stem by the antrum.

Other Conditions

We do look at the ge junction at times.
There have been several papers suggesting
that we can use, ultrasound to assess for
gastroesophageal reflux.
There are uneven standards currently,
however, for grading.

When we look at the abdomen in the neonate, there are other
masses that we can identify, including several cysts.
Duplication cysts are one of them,
and these can be masses anywhere adjacent to any
of the bowel.
They can be somewhat cystic or tubular.
They can be fairly benign but can present with obstruction
or biliary obstruction.

So duplication cysts as mentioned can ha can be clear.
They can have some debris within them
using your high linear transducers.
You can see the double mucosa sign
that can really differentiate this from other simple cysts.

One of the other differentials when we see cystic
collections in the abdomen include cholico cysts.
These can be, within the region of the bile duct
or a separate cyst.
We don't quite understand why choli ductal cyst develop,
whether it's the failure of separation, the common bile duct
and pancreatic duct or a congenital weakness of the wall
of the common bile duct.

There are several different classification systems
and can be associated with extrap bili atresia.
So here's the Tani classification
and beware that all of these can present as
cyst cysts in the right upper quadrant
or type fives,
which actually could be cysts within the
liver confirmation.
Besides ultrasound can include
our hepatobiliary scans and now cps.

When we look at that r upper quadrant, we can look
for the gallbladder and common bile ducts
and at times neonatal cothesis can present itself.
Risk factors include prematurity, infants
that are in TPN with prolonged fasting dehydration,
phototherapy all can increase the risk of,
these stones developing.

So, some of these patients can have actual calculi,
others may simply have sludge with dilated bile ducts.

Intussusception

Lastly, I'll just talk a little bit about intussusceptions.
This is actually re relatively rare in the neonate if it
does present this early.
Look carefully for potential pathologic lead points.
As we saw in this case, this was a meles
diverticulum in an intussusception
for intussusceptions.

You can see, the demos wall of the septum
with a central echogenic city representing,
central compressed mucosa with intestinal contents
on the longitudinal views.
This looks more like a pseudo kidney with hypo code mass,
right central echoes in the central aspect.

Again, this is another example
of a mecal diverticulum in a relatively younger neonate
with an inci septum that required resection.

Small bowel interceptions can also be identified at times.
They also can be secondary to, lead points such
as polyps, mekel, diverticulum,
and just be aware that these are more transient
and do not require, NMS to reduce them.

Conclusion

So we went through a lot of different initials.
When we look at a neonate with, potential abdominal
emergencies, ultrasound is a wonderful modality
but is operator dependent.
And we have to decide where we are gonna be, looking.
Do we look at the entire abdomen?
Do we measure everything or do we do a focal exam?
These infants are quite unstable,
and they may have,
issues when you're pressing on the abdomen.
So gentle handling is quite important.

We wanna make sure that you keep the transducers clean,
your hands clean and keep the infant warm in the
in incubator.
These can be very long studies
and yet the infants may be too fragile
to handle such a long exam.
So you may need to do a more more focused study
and to keep them warm.

Overly gas, when there's dilated bowel loops,
can also limit, imaging.
You wanna make sure that your mechanical indexes as low
as possible because there have been reports of,
heat generation with your high thermal indexing
mechanical in indexes.

So remember, use prewarm hypoallergenic ultrasound gel.
Remember, these are very vulnerable infants, so you need
to perform them, with semi sterile conditions.
And it's important to always correlate
with the abdominal film what you're seeing by ultrasound.

So ultrasound is a wonderful tool for the assessment
of many neonatal bowel conditions.
Be creative, use that high linear transducer.
Use your doppler. Look at real time.
But remember, studies may be equivocal
and require fluoroscopy
or abdominal films to help make a more specific diagnosis.

Thank you for your time.