Ultrasound of the Vomiting Infant - HD

Introduction

Hello everyone.
My name is Harriet Paul Thiel.
I'm a radiologist at Boston Children's Hospital,
and I look forward to discussing ultrasound
of the vomiting infant with you.
Vomiting, as you all know, is the forceful extrusion
of gastric contents,
and it's a very common symptom in infants.
It's never normal, but it is nonspecific
and maybe due to disorders both within
and outside of the GI tract.
When it's prolonged, it may produce dehydration
and electrolyte imbalance.
What I plan to do in the next half hour
or so is to review the role of ultrasound
and the imaging findings in evaluation
of the vomiting infant.
And I will discuss the following entities
that are listed here, including pyloric stenosis,
mid gut mal rotation, and volvulus
proximal small bowel atresia
and stenosis, meconium ileus duplication cyst,
inguinal hernia, intussusception
and gonadal torsion, including both testicular
and ovarian forms.

The Role of Imaging in Vomiting Infants

The role of imaging is to exclude
or to document anatomical obstruction
of the GI tract when the clinical diagnosis is uncertain.
As you know, fluoroscopic contrast examination is the
primary means of evaluating the mucosal
and luminal abnormalities,
whereas ultrasound is extremely useful in depicting the
bowel wall and extrinsic abnormalities
and has become the modality of choice.
In screening infant for hypertrophic pyloric stenosis,

Pyloric Stenosis

pyloric stenosis is characterized by abnormal contractility
of the pyloric circular muscle,
and there is hypertrophy
of this muscle resulting in a constriction
of the pyloric channel.
The incidence is approximately one in eight hundred live
births in North America, and its etiology is unknown.
Here on the left we have a schematic diagram
of pyloric stenosis.
Here you see a cutaway image showing the very elongated
pyloric channel with narrowing
and the thickened musculature.
On this cross-sectional view,
you can see the little pinpoint lumen.
Here's an external view of the stomach,
and this bottom image is meant to show a wave
of peristalsis, which is characteristic of this disorder.
On physical examination here on the right is an actual
intraoperative photograph of a patient
with pyloric stenosis,
and you can see that the muscle has been incised,
and we see the mucosa of the pyloric channel,
poking through.
Boys are affected four to five times more than girls,
and the incidence is significantly higher in
first born males.
There is a familial predisposition as well.
Symptoms may occur anywhere from birth to about five months
of age, but this entity is most commonly diagnosed
between the ages of two and six weeks.
And on physical examination
an epigastric, olive shaped mass is palpated in up
to about 80% of affected infants.
There are a lot of numbers that appear in the literature,
but few would dispute the fact that a thickness
of the pyloric musculature four millimeters
or more is abnormal.
And similarly, that the pyloric channel length
of 18 millimeters or more is also definitely abnormal.
Muscular thickness appears to be the most discriminating
and accurate measurement.
And the other important finding is
that there is a fixed muscle abnormality.
With time, some infants have pyloric spasm,
and if you observe their pylorus
for several minutes, you'll see
that there's a change in the thickness of the muscle.
Whereas with true hypertrophic pyloric stenosis,
this finding is fixed.
There is a gray zone of muscular thickness between two
and four millimeters that can be normal or abnormal.
We tend to see these lower measurements in infants
who are less than four weeks of age who may
have hypertrophic pyloric stenosis or premature infants.
And also as I mentioned earlier, in the setting
of pyloric spasm,
where this thickness will not be fixed over time.
So here's an example of a patient with pyloric stenosis,
and we obtain these images in the epigastric region.
A transverse image through the upper abdomen will display the stomach
and the pyloric channel, which we see here.
And the abnormal finding that is of interest
to us is the marked thickening of the muscularis.
Here propria, this is where we make our measurements.
And on these transverse images, we get a sagittal view
through the pyloric channel, which seems to be
the most accurate.
Here's a transverse image,
which also shows the thickening,
but it's often easier
to obtain your measurements on a
sagittal view of the pylorus.
Here we see the pyloric canal,
we can see the echogenic mucosa, the muscularis mucosa,
the echogenic submucosa,
and then the muscularis propria.
And also note how elongated this pyloric channel is as well.
Here are a couple of image clips,
pretty characteristic findings.
You see how stiff this pylorus is.
It's contracting, but you can see it's not pliable,
and it's very elongated as well.
Here on the right we have another clip
where you can actually see regurgitation of fluid
from the duodenum back into the stomach.
And some of these infants may be vomiting as well.
And that is one common presentation of pyloric stenosis.

Bilious Vomiting in the Newborn

I'd like to move on now to a discussion of the newborn
with bilious vomiting.
This is different from pyloric stenosis
where the patients do present with vomiting,
but it's non bilious
because the site of obstruction is in the region
of the pyloric channel.
With bilious vomiting,
there's always a concern about mid gut volvulus,
where the level of obstruction is lower down.
And in the setting of midgut volvulus,
there may be ischemia
and necrosis of the duodenum and small bowel.
Other causes
of bilious vomiting include proximal small bowel atresia
and stenosis, as well
as congenital extrinsic obstructing lesions such
as duplication cysts.
Patients with bilious vomiting are generally worked up
with plain films, upper GI series
and ultrasound.
On occasion, the plain film
may show dilation of the stomach
or the small bowel to the point of obstruction,
which obviates the need for further imaging.
However, that being said, most studies in fact are normal
or have non-specific radiographic abnormalities.
The upper GI series, it's important to remember,
is the examination of choice for the diagnosis
of small bowel mal rotation and obstruction.
And it's important to document the position
of the duodenum to determine whether
or not there's a beaked
or twisted point of obstruction.
As can be seen with mid gut volvulus,
and in the setting of atresia
or stenosis, there will be dilated bowel proximal
to the site of obstruction.
So here is a normal duodenal jejunal
junction on an upper GI series.
We see the stomach, the duodenal bulb,
and the normal course of the duodenum, which
sweeps down and around and crosses the spine.
And terminates,
you see the duodenum terminates at the DJJ at about the same
level as the pylorus.
Ultrasound is not the primary screening modality,
however, it is often very useful in patients
with atypical symptoms and non-specific plain film findings.
Other ultrasound signs
that have been described is the so-called SMA SMV
inversion sign, which can be seen in malrotation.
The whirlpool sign
of Midgut Volvulus has also been described,
and in the case of a duplication cyst,
you can directly visualize the cyst with ultrasound.
So ultrasound has an ancillary
but often very important role to play in the diagnosis
of the patient with bilious vomiting.

Midgut Malrotation

Mid gut mal rotation, as you know,
is related to the congenital narrowing
of the mesenteric pedicle.
Here we have a diagram showing the normal course of the mesentery.
And here with malrotation it's very short.
This results in an abnormal anterior position
of the duodenal jejunal junction.
And in these patients, the bowel is fixed
with peritoneal bands in an attempt to stabilize
its position.
And occasionally these peritoneal bands may lead
to obstruction or internal herniation.
There's also a predisposition of the bowel
to twist around the superior mesenteric artery.
And this in turn can lead to vascular occlusion
and bowel ischemia.
The SMA SMV inversion sign has been shown to be a sign
of midgut mal rotation, but it is not pathognomonic.
And if you do see it in the appropriate clinical setting,
then it is important to confirm
the abnormal ultrasound findings with an upper GI series.
There are cases that have been reported in the literature,
and I personally have seen some cases as well,
where patients may demonstrate this inversion sign,
but they in fact do have a normal bowel position.
That being said, it can be helpful.
So here is a normal SMA SMV relationship on a transverse ultrasound image.
Through the epigastrium, we see the superior mesenteric artery here surrounded by fat,
and the superior mesenteric vein is normally located
anterior and to the right of the superior mesenteric artery.
Here we have the splenic vein.
Joining up with the superior mesenteric vein right here.
Here's an example of an inverted vein.
So again, we have the superior mesenteric artery surrounded
by fat, and then anterior
and to the left of the artery,
we see the superior mesenteric vein.
Here is an upper GI series showing midgut mal rotation.
You see that the proximal small bowel loops are
abnormally located to the right of the spine.
And on the lateral view, you see this peculiar kinking
of the duodenum
and proximal small bowel, presumably related
to the presence of Ladd bands.
Some have described a so-called Z
or ZED sign that likened the appearance of this proximal bowel to the letter Z
or ZED.

Midgut Volvulus

Mid gut volvulus.
This is a twisting of the mid gut that occurs as a result
of bowel rotation with occlusion of the superior mesenteric artery
and vein leading ultimately to ischemia and infarction.
And here you see a diagram showing the twisting
of the midgut. On the right is an actual clinical photograph
taken at the time of surgery in someone with a midgut volvulus.
And you can see how dusky
and abnormal these loops of small bowel are.
Just a couple of plain film examples
of two different patients with mid gut volvulus,
although they look very abnormal.
Here on the left, we have some dilated bowel
and kind of abnormal aeration of the
remainder of the bowel loops.
It's really a non-specific appearance.
Similarly, on the right dilated bowel loops,
some separation presumably related to bowel wall edema,
probably some free fluid as well.
So these are nonspecific but abnormal plain film findings.
The ultrasound whirlpool sign has been described in
patients with midgut volvulus.
So we do see that there is an inversion
of the SMA SMV relationship on this upper left hand image.
And here we see a peculiar appearance here of some vessels.
And with a power doppler you can see very readily
that there is a very abnormal swirling of the vessels.
And this is the so-called whirlpool sign.
Couple of other barium studies of patients
with mid gut volvulus.
Here on the left we have the so-called corkscrew sign
where the twisting of the bowel
around the superior mesenteric artery has the appearance
of a corkscrew.
And here on the right are two images of a patient
who has actual obstruction of the duodenum
with some beaking just proximal to the point
of obstruction.

Other Obstructive Causes of Bilious Vomiting

Other obstructive causes of bilious vomiting include
atresia and stenosis.
Meconium ileus, extrinsic mass lesions,
inguinal hernia intussusception,
and I do mention Hirschsprung's disease, but I put it in brackets
because it's an extremely sort of
non-specific presentation of Hirschsprung's disease,
and I'm not going to discuss it any further.

Duodenal Atresia and Stenosis

Duodenal atresia
or web may be detected on prenatal sonography
with atresia presenting shortly after birth.
The diagnosis of a web or of a stenotic portion
of the bowel is sometimes delayed.
Postnatal ultrasound may be diagnostic
with the bowel proximal to the site
of obstruction appearing dilated and filled with fluid.
Here's one patient who had a duodenal web,
and on the image here, you can see there's a dilated stomach
and pylorus and we're
seeing fluid filled duodenum,
a little bit distal to that.
Here you see the very short
and not normal thickness pyloric channel,
and then this very distended duodenum filled with fluid.
And on this clip you can see the contents of the duodenum sloshing back and forth,
and the dilated segment
terminating about here.
This is another patient with a duodenal stenosis.
We see a very dilated air-filled stomach with some gas distally.
And on ultrasound, again,
we see proximal dilation of the duodenum.
But it comes to a termination here
where the red arrow is.
And this patient did have a barium study,
and again, you see a very distended stomach and duodenum,
and then marked diminution in the caliber
of the bowel at the site
of the stenosis.
A delayed image does show
that the barium clears from the stomach and the duodenum
and entered here into the colon, so it was a stenosis
and not a complete obstruction.
These often present later, for obvious reasons, they're not
as dramatic as the atreias or the webs.

Intestinal Atresia

Intestinal atresia is a complete luminal occlusion, ischemic
in etiology that occurs more commonly in the jejunum
and ileum than in the duodenum or the colon.
The prenatal interruption
of the vascular supply occurs in sterile bowel,
and the avascular portions of the bowel simply disappear.
Intrauterine ischemia may result from malrotation,
volvulus, hernia, intussusception,
or kinking of the bowel
with the cause being apparent in only about 25%
of patients at the time of surgery.
These patients usually present on day one of life
with bilious vomiting, abdominal distension
and a failure to pass meconium. And antenatal.
An antenatal diagnosis is usually made
after 24 weeks of gestation.
The patients will have polyhydramnios
and dilated bowel. Postnatal plain films
and contrast enema are the mainstays of diagnosis after birth
with enema performed
to demonstrate colonic position
and to exclude meconium ileus
and colonic causes of obstruction.
So here is a patient with jejunal atresia who was
diagnosed with a bowel problem prenatally.
Here on the ultrasound you can see distended loops
of bowel filled with meconium pellets.
The patient did have a prenatal MRI examination,
which shows similar abnormal bowel.
I think the resolution of the ultrasound is better,
and you could make out more detail.
Here's the same patient at birth postnatal imaging.
So we see a big distended bowel loop in the mid abdomen
and a micro colon here on the
contrast enema without filling of
the dilated loop.
So a presumptive diagnosis of a small bowel atresia was made
and was shown to be in the jejunum at surgery.

Meconium Ileus

I'd like now to move on to a discussion of meconium ileus,
which occurs in 10 to 20% of patients with cystic fibrosis.
It is almost always a manifestation of CF.
And as you know,
these patients have abnormal pancreatic enzymes
and mucus gland secretions, the abnormal meconium obstructs
the distal small bowel
and prenatally bowel dilation
and echogenic bowel may be seen.
So here are examples of two different patients
with cystic fibrosis and meconium ileus.
In this case.
On the left, you see dilated fluid-filled bowel.
On the right, we see that the bowel walls are echogenic.
The patients will present with bilious vomiting,
abdominal distension, and a failure to pass meconium.
And up to about 50% of cases will be complicated
by volvulus atresia bowel perforation,
pseudocyst formation or meconium peritonitis.
Patients will undergo a variety
of imaging including radiographs,
which will show dilated small bowel with a granular
or bubbly bowel gas pattern.
There may be intraperitoneal calcification.
If there has been a perforation,
there may be a large gas shadow related
to the presence of a pseudocyst.
A contrast enema will show a micro colon
and inspissated ileal meconium.
So here is a patient with meconium ileus.
You'll notice on the left on the plain radiograph,
this soap bubble appearance of the bowel loops
very characteristic of this entity.
On the contrast enema, we see a micro colon,
and there is some filling of distal small bowel here,
which is filled with meconium as well.
Here's a patient with a pseudocyst, very peculiar
air shadow in the midline on plain radiography here,
or a couple of ultrasound images.
This is a sagittal image
and the red arrow is actually pointing to the bladder.
And then you have this huge complex cystic structure in the mid abdomen,
which has innumerable echogenic linear foci,
presumably related to the presence of air within this abnormal collection.
And we see on a contrast study that was done that it’s outside of the bowel.

Duplication Cysts

I'd now like to talk about duplication cysts.
The most common sites
of involvement are listed here, the distal ileum, esophagus,
stomach, and duodenum,
and the remainder are scattered throughout the bowel.
Patients may present
with vomiting if there is associated upper GI tract
obstruction, abdominal pain
and hemorrhage if there's peptic ulceration because some of these cysts do contain gastric mucosa
that secretes hydrochloric acid,
or they may present as a painless mass.
And here is one example of a duplication cyst at surgery,
displacing bowel loops.
Here we see it removed.
And here a histologic slide of the wall by ultrasound.
These cysts appear as well-defined unilocular masses
with echogenic mucosa, which may be ulcerated
by gastric enzymes.
The muscle wall appears hypoechoic.
The contents are a variable echogenicity.
Occasionally they may appear echogenic
or septated if there's inspissation of the contents
or if there's associated hemorrhage.
Here's a patient with a duplication cyst.
We see that there are some echogenic foci within it, some debris.
Here we see it.
The cyst in relation to the liver
and the kidney here is a sagittal view,
again pressing up against the liver.

Inguinal Hernia

Inguinal hernia.
Now, most of the time we don't need to perform ultrasound
to make this diagnosis.
They're usually clinically obvious,
but occasionally they're not.
The vast majority in children are indirect in the male fetus.
The peritoneum prolapses into the inguinal canal.
We can see in this diagram on the right
normal anatomy here on the left, in the female, the prolapse occurs into the inguinal canal and labia majora
and the bowel herniation occurs through an open
communication with the peritoneum.
Inguinal hernias are much more common in boys than in girls,
almost 10 to one.
Most are asymptomatic.
About 10% are irreducible
and only a very small proportion will undergo strangulation,
and that means that they're irreducible and nonviable.
They may be associated with bowel obstruction as well.
And as I've mentioned, the diagnosis is usually clinically obvious.
Here we see a patient with a hernia here on the left.
Plain films may show dilated small bowel
with gas fluid levels indicating obstruction.
Here we see quite a dramatic example
with dilated bowel loops in the abdomen
and also filling both scrotal sacs.
Ultrasound is useful in assessing the scrotum,
the labia, and the inguinal canal structures
with peristalsis favoring a viable bowel
and its absence suggesting ischemia.
Here we see a patient where you can see
that there's herniation of bowel into the inguinal canal.
Here is a patient who had an incarcerated inguinal scrotal
hernia that was associated with testicular ischemia.
And the patient's symptoms were actually those of
testicular ischemia.
And the hernia was really only visualized by ultrasound and then surgically treated.
But you can see here in this transverse view
of the scrotum, we have the normal left testicle,
and then the right testicle, which is markedly hypoechoic.
There's no blood flow documented with color doppler.
And here we actually see the hernia enveloping.
This testicle.
Here's an example of an incarcerated inguinal hernia in a
two month old girl.
This is a transverse view of the groin.
And these xs are overlying both ovaries.
And here you can actually see the uterus,
which has herniated out into the inguinal region.
Here we see one ovary.
Here's the other ovary,
and I have a clip here to show you as well.
And here you can see the uterus,
which is herniated out into the groin just below the skin surface.

Intussusception

A few words about ileocolic intussusception.
This is the most common abdominal emergency in early
childhood with patients usually aged
between two months and two years.
And most commonly, a distal ileal loop.
The intussusceptum invaginates into the cecum
and proximal colon, which receive it, the intussuscipiens, along
with associated mesentery.
And this results in compression with venous
and lymphatic congestion that may ultimately lead to edema,
ischemia, perforation, and peritonitis.
If the obstruction is not relieved in a timely manner.
The majority of cases are idiopathic
with a pathological lead point identified in only about 25%
of cases, most commonly a Meckel's diverticulum,
a polyp, a duplication cyst, or small bowel lymphoma.
In the rest of the cases, the thought is
that there are usually hypertrophied Peyer's patches,
often following a prior infection, gastroenteritis, and that these hypertrophied Peyer's patches
lead to the intussusception.
So the most common location, as I've mentioned,
is in the ileocolic region.
And the classical triad is that of pain,
a palpable sausage shaped abdominal mass
and currant jelly stool.
But this triad really occurs only in a minority of patients.
Here is an example of currant jelly stool.
For those of you who are not familiar with currant jelly.
And if patients have had this and
the obstruction has not been relieved,
they may present with lethargy and with vomiting.
So here is a typical example of a patient
with intussusception.
We see on the plain radiograph
that there is a soft tissue mass within
the transverse colon here.
And on this image, if you look carefully,
there's a central area that appears empty,
presumably related to the invagination of mesentery into the bowel.
This is a typical ultrasound appearance of intussusception,
a bowel within bowel appearance or a target sign.
And these images along the bottom row are of the bowel taken at the time of reduction with air.
So we do see the intussusception here outlined
by air here.
We see it down in the region of the cecum.
And finally, once it's been reduced, we have free reflux
of air into the distal small bowel.
Here's a patient who had an intussusception related
to the presence of a Meckel's diverticulum.
You can see here on the left a transverse view of the bowel.
And here's the diverticulum. It's on a stalk.
Here, you see the head of it.
This patient did have a contrast enema.
You can see this coiled spring appearance
of the intussusception.
There used to be a lot of different contrast enema signs described in the literature.
This was one of them, a coiled spring appearance.
We don't tend to see that when we do air reduction, which is
what we use most of the time.
Here is a patient with a Meckel's diverticulum,
everted.
You see, it has a very similar appearance to this ultrasound image.

Gonadal Torsion

A few words about gonadal torsion,
which may present with vomiting.
There is a bimodal distribution.
This occurs in the perinatal period
and then again in early puberty,
but can really occur at any age.
In the perinatal setting,
it's usually an extravaginal process with a twisting
of the spermatic cord
and torsion involving the entire testicle with the tunica
vaginalis not well fixed to the scrotal wall.
Perinatal torsion may be acute or chronic.
Generally speaking, the acute presentation is that
of a tender swollen testis
and no distress with a chronic presentation
in the older infant.
The pathophysiology
and clinical presentation are the same as
that in the adolescent.
It's an intravaginal process with a twisting
of an excessively mobile testis because the tunica
vaginalis, which is
represented schematically here, is inserting abnormally high on the spermatic cord.
And these patients may present with pain,
nausea, and vomiting.
So here's a six month old boy with testicular torsion.
And here are some images
of the ultrasound examination.
Here on the symptomatic side, you can see
that there's a lot of swelling of the tissues
of the scrotum.
There's a hydrocele.
Here's the normal testis with blood flow documented with color doppler.
Whereas on the torsed side,
we do see some blood flow, but it's really at the periphery.
It's in the scrotal wall,
but not within the testicle itself.
Ovarian torsion also may present with pain,
a mass nausea and vomiting.
It consists of a partial
or complete rotation of the ovary on its vascular pedicle,
resulting in compromised venous and lymphatic drainage
and arterial inflow.
It's almost always unilateral,
and the pathological findings may range from massive edema
to parenchymal necrosis.
We have an example here of a torsed ovary.
Most cases in the neonate
and infant are related to the presence of an ovarian cyst.
And a normal ovary can undergo torsion,
thought to be due to hypermobility related
to lack supporting ligaments.
The affected ovary is always enlarged,
and that's very helpful from a diagnostic
ultrasound point of view.
The average volume is about 12 times that
of the opposite normal ovary.
And when the volume on the abnormal side is more than 20 times that
of the normal ovary.
This is generally associated
with the presence of a mass.
Ovarian cysts are occasionally detected prenatally.
They're usually unilateral,
and the majority are believed
to result from ovarian stimulation by fetal
and maternal gonadotropins.
They may appear simple or complex by ultrasound.
They may be palpable and most asymptomatic
and regress prior to birth.
Bleeding into an ovarian cyst in utero or after birth.
It has a very high association with long-term ovarian loss.
And this loss is thought to be due to torsion.
And there is a suggestion
that ovarian dysgenesis may be the underlying cause.
And I listed here two papers that explore this association further.
Here's a patient
with a prenatally detected ovarian cyst.
We see the placenta. Here's the cyst.
And when the patient was born, there was a huge cystic mass in the abdomen.
This is a sagittal view showing the huge cyst extending all the way up into the region of the right kidney here.
Here's the bladder. Again, an enormous cyst
with a fluid, fluid level.
Here we see the uterus
and no flow within this mass with color doppler.
And the patient did undergo postnatal
laparoscopy and did have torsion of a hemorrhagic cyst at pathology.
Here's another patient, a 17 week old girl with vomiting
and right lower quadrant pain who had ovarian torsion.
You see the massively distended follicles on these images.

Summary

So in summary, I have reviewed with you the role
of ultrasound and the imaging findings in the vomiting
infant, the large variety of pathologic diagnoses,
pyloric stenosis, midgut malrotation and volvulus proximal small bowel atresia
and stenosis, meconium ileus duplication cyst,
inguinal hernia intussusception, and gonadal torsion.
Thank you.