Anomalies of the Fetal Gastrointestinal & Genitourinary Tracts - HD

Introduction

Hello, my name is Dr. Carol Benson.
I'm from Brigham and Women's Hospital in
Boston, Massachusetts.
Today my lecture will be to discuss anomalies
of the fetal gastrointestinal and genital urinary tracts.

Fetal Abdomen

The fetal abdomen is the part of the body
below the diaphragm in the trunk of the body.
The images that we typically take
during an obstetrical ultrasound exam include the
measurement of the abdominal diameter at the level
of the stomach and tatic portion of the umbilical vein.
We take images of the kidneys, the urinary bladder,
and we also take an image
of the anterior abdominal wall at the umbilical
cord insertion.

Stomach Assessment

On the abdominal measurement view,
the first thing we do is assess the stomach
to make sure that it's present.
This is done in order to exclude such anomalies
as esophageal atresia or diaphragmatic hernia.
We look at the stomach location to make sure
that it's in the proper location rather than having a
situation such as SI sinus and versus orus ambiguous.
We look at at its size to exclude bowel obstruction
and on the same view we look for other fluid collections
that are present that shouldn't be there, such as
with duodenal obstruction
or when there is another lower bowel obstruction.
So this is a view of the fetal abdomen.
With the abdominal diameter measurement, you can see
that we have a transverse view of the abdomen.
The abdomen is round
and we see the stomach in the left upper quadrant
of the fetus and the portion of the umbilical vein
and the measurement is taken from skin surface
to skin surface, anterior posteriorly and transverse.

Absence of the Stomach

If the stomach is not seen in the left upper quadrant,
this may actually be a sign of a normal fetus
who just has not swallowed recently.
And if you follow this fetus for 10
or 15 minutes, you should see the
fluid in the stomach later during the examination.
But a persistent absence
of the stomach may represent an anomaly such
as esophageal atresia
or left diaphragmatic hernia
where the stomach is not in the abdomen
but rather in the chest or a cleft lip
or some central nervous system anomalies
where the fetus can't swallow
or with a sinus abnormality
where the stomach is somewhere else in the abdomen.
Besides the left upper quadrant, absence
of the stomach may also be seen when there's severe oligo
hydrus and no fluid for the fetus to swallow.
So here's a fetus scanned at 18 weeks gestation where
during the entire exam no fluid was seen in the upper
abdomen in the left upper quadrant
or anywhere in the left upper abdomen.
And here are two representative images
on her return at 21 weeks gestation.
We learned the reason why there was failure
of filling of the stomach.
It was because the fetus had a bilateral cleft lip.
You can see on this coronal view of the face,
a cleft on the upper lip on each side
with the central maxillary prominence.
And here on the clip you can see
that large defect which prevented the fetus
from swallowing properly.
This fetus has tus inversus.
So instead of finding the stomach in the left upper
quadrant, the stomach was found in the right upper quadrant.
This fetus did have a complete sinus inversus,
so examination of the chest shows
that the heart was also on the right instead of the left.

Echogenic Bowel

When echogenic bowel is seen in the fetal abdomen
during the second trimester,
it may indicate an underlying abnormality.
Echogenic bowel is associated with cystic fibrosis,
intrauterine growth restriction trisomy 21 and 18
and can also be seen in fetus who's had had some bleeding
during the pregnancy
and the fetus then has swallowed the blood
that has been tracked into the amniotic cavity.
So here's a fetus at 18 weeks gestation with a clump
of echogenic bowel.
You can see it here on the coronal view of the fetus.
Next to the iliac crest is a clump of bowel that is
as bright as the bone
and on transverse view
of the lower abdomen we see this clump of echogenic bowel.
This fetus proved to have trisomy 21.
You can see in addition to the echogenic bowel,
the fetus had the typical cardiac defect often seen
with trisomy 21
and atrial ventricular canal can see the defect in the
ventricle ventricular and atrial septums
and the abnormal atrial ventricular valves.
This fetus also has echogenic bowel.
You can see on this longitudinal view of the fetus,
this clump of bowel that's genic
and on this transverse view, this loop of echogenic bowel.
And this is present because the there has been a bleed.
There's a large sub chorionic hematoma.
Some of the blood has tracked into the amniotic fluid
that the fetus swallowed causing the echogenic bowel.

Amniotic Fluid and Swallowing

I've already mentioned a little bit about amniotic
fluid and swallowing.
Amniotic fluid is surrounds, surrounds the fetus
and provides support for the fetus
and allows the fetus to move and to grow.
The level of amniotic fe of amni.
Amniotic fluid is dependent on a homeostatic balance
between the amount of renal function, the amount of fluid
that the fetus produces by urinating
and the amount of swallowing
and gastrointestinal absorption.
So here we can see this in a schematic format.
The fetus does swallow the amniotic fluid
and then the fetus does replenish the amniotic fluid
by urinating into the amniotic cavity.
When there's diminished or absent swallowing
or if there's inadequate fluid resorption in the
gastrointestinal tract,
excess fluid will collect in the amniotic cavity
causing polyhydramnios.
This is particularly common in cases
where there's gastrointestinal obstruction.
The higher the obstruction, the greater the degree
of polyhydramnios.
So when the obstruction is that the level of the esophagus
or the stomach or duodenum,
you'll have pretty severe polyhydramnios.
But if it's more distal in the juju
and meum we you may have mild polyhydramnios
and with colonic obstruction,
there be no may be no polyhydramnios at all.

Esophageal Atresia

So with esophageal atresia you'll have severe polyhydramnios
and an absent or very small stomach.
Here's an example of that.
Notice the large amount
of amniotic fluid surrounding this fetus.
Here's the fetal chest with the heart beating
and here's the fetal abdomen.
We're scanning through the upper abdomen
and we see no stomach here.
Because of the esophageal atresia, the fetus was unable
to swallow the fluid into the stomach.
Here's a fetus who actually did have esophageal atresia,
mild polyhydramnios,
but this fetus also had a trache esophageal fistula
and for this reason we saw fluid in the upper abdomen
inside the stomach,
but we also were able to see the upper esophagus.
Here you can see on a view
of the fetal neck we have the trachea, which is fluid filled
and behind the trachea is a little bit
of fluid in the upper portion of the esophagus.
A little while later this fluid extended down lower
and expanded the upper part of the esophagus
and eventually filled it here.
Of course, this is as far as it will go
because this is the site
of the atresia.

Gastric Outlet Obstruction

Gastric outlet.
Obstruction is rare but not unheard of.
It typically results from pyloric atresia either
as a primary anomaly or secondary to a vascular insult.
The findings on ultrasound include polyhydramnios
and a dilated stomach.
So here's a fetus at 35 weeks gestation surrounded
by mild polyhydramnios
and the stomach was persistently dilated throughout the
examinations of this fetus.
This fetus proved to have pori atresia.
You can see that after birth they've taken
an x-ray of the baby.
The stomach is filled with air,
but no air has passed from the stomach into the rest
of the gastrointestinal tract.

Duodenal Atresia

With duodenal atresia, there's obstruction
of the duodenum either by atresia or by a web
or an annular pancreas.
The sonographic findings are characteristic.
There's a double bubble of fluid in the upper abdomen.
In addition, there will be polyhydramnios
duana laia is associated
with other anomalies in more than 50% of cases.
So if you do make this diagnosis,
do look carefully at the rest of the fetus to try
to identify other anomalies.
Look at the vertebral body as and the skeletal system.
Look for other gastrointestinal anomalies.
Look for cardiac anomalies, genital urinary anomalies
and in addition, the rate
of trisomy 21 is quite high in these fetuses and
therefore the parent should be counseled that the risk
of trisomy 21 is about 30%.
Here's the typical sonographic appearance
of duodenal atresia In the upper abdomen you have two
fluid-filled structures dilated.
As we see here, these represent the dilated stomach
and the dilated duodenal bulb.
If you scan down a little bit inferiorly
to this classic view, you will be able to see the connection
between the stomach
and the duodenum through the dilated pylorus.

Distal Bowel Obstruction

Bowel obstruction distal
to the duodenum can occur at the jejunum, the ileum
or even the colon,
and may result from a VA vascular accident from a volvulus
or be the result of meconium plug or an intussusception.
On ultrasound, we'll see dilated loops of bowel.
The more distal the obstruction is, the more loops
of dilated bowel we will see.
We also may have polyhydramnios.
So here's a fetus with juju atresia.
The juju juju is high and
therefore we only see one large loop of dilated bowel
that's dilated because of the atresia.
Below this point, in this case there was
mild polyhydramnios.
This fetus has a distal bowel obstruction at the level
of the ileum and that's why we see multiple
dilated loops of bowel.
Notice that when the loops of bowel are dilated with fluid,
that there's rapid peristalsis throughout
and this is typical of a bowel obstruction.

Meconium Peritonitis

Meconium peritonitis is something that happens
after the bowel perforates inside the fetus
with the perforation.
Meconium spills into the peritoneal cavity
and causes a chemical peritonitis.
The first finding on ultrasound in these cases is ascites.
Eventually the ascites will be walled off into a cyst
and calcifications will collect in the wall of the cyst.
In addition, wherever the the meconium has spilled into the
peritoneal cavity, calcifications will be seen
lining the peritoneal cavity
and eventually the cystic fluid will be resorbed.
Here's a case we were able to follow
through gestation at 16 weeks.
A diagnosis was made of free fluid in the fetal abdomen
with no other sign of hydrops At 21 weeks gestation,
we no longer had free fluid in the abdomen,
but we now had a cystic structure in the upper abdomen
with calcification in the wall of that cyst.
This represented a meconium cyst
with the meconium calcifications As time went on,
the fluid in the cyst was resorbed
and the fetus was left with calcification lining.
The peritoneal cavity,
we can see it here on the undersurface of the liver
and we can see it along the anterior surface
of the abdominal wall within the peritoneum,

Small Bowel Volvulus

A small bowel ovulus will result when the bowel is
incomplete, fixated to the posterior mesentary
and so it can rotate
and this rotation will lead to strangulation of the bowel
and obstruction to the bowel proximal to that site.
On ultrasound, we may have acute onset
of polyhydramnios which results at the time of the ulous
and we will see dilated loops of small bowel proximal
to the site of the twist.
We may also see the the loop that has twisted
as a single larger dilated loop
and we may see the whirlpool sign of the twisted mesentery.
Here's a fetus where we do see that whirlpool sign.
On the still image, you see the dilated loop of the ulu.
And then if you watch on the clip, you can see the whirlpool
of the curling around of the bowel
and mesentery that led to the twisting of this loop.
Here's another fetus with the ovulus,
we see a very large dilated loop of bowel.
This bowel was twisted
and it was twisted so tightly that it lost its blood supply
and so this loop was dead by the time the baby was born.
Notice on the clip we do see dilated loops of bowel
and these were proximal to the site of the obstruction.

Anterior Abdominal Wall

Now we also look at the anterior abdominal wall.
The only thing that should cross the anterior abdominal wall
is the umbilical cord.
Nothing else should be protruding from the anterior
abdominal wall in a normal fetus.
So we look at this in order to exclude an Amal seal,
a gastroschesis or disruption by the amniotic band syndrome.
So in a normal fetus, when we look at a transverse view
of the abdomen, the only thing protruding from the anterior
abdominal wall should be the umbilical
cord Of num.

Omphalocele

Falle is an abnormal protrusion from the anterior
abdominal wall.
This defect is at the ventral wall at the site
of the umbilicus
and through the defect, abdominal contents herniate in
into a sac that's covered by a peritoneal membrane.
Um, fall seals are commonly associated with other anomalies,
so look at the fetus carefully
and also the council counsel the patients about the
increased risk of aneuploidy.
So here is a fetus
with an valase seal on a longitudinal view of the fetus,
we see protruding from the anterior abdominal wall,
a well-defined smooth mass that represents the emale sac.
On transverse view we can see
that the spine is posteriorly located.
We have the stomach pulled anteriorly
and interabdominal contents are herniated anterior into
the emale sac.
Running through the sac is the umbilical cord which
traverses it and then exits from the other side
of the emale.
We can also look at this with 3D.
Ultrasound here are two 3D ultrasounds from a fetus
with an emale showing the bulging sac from the fetus.
And what's characteristic of an emale on 3D is
that the outer surface of the emale is nice and smooth
because remember it's covered by a peritoneal membrane.
Here's another fetus with an emale.
The emale sac is bigger than the fetal abdomen.
Here's the fetal abdomen.
The spine posteriorly the stomach here in the left upper
quadrant and then protruding from it is a large um,
falle sac also having some fluid in it as well
as intraabdominal contents.
And here's the 3D of that fetus showing that very large
but smooth walled um, falle.

Gastroschisis

A gastroschesis is another abdominal wall defect
that's different from an emale.
It's next to the umbilicus, not at the umbilicus.
It's more common on the right than the left.
And this defect allows abdominal contents
to herniate into the amniotic cavity.
The abdominal contents are not contained
by a peritoneal membrane and
therefore the contour is not smooth like an valase seal.
Also with a gastroschesis. Other anomalies are uncommon.
Gastro skies are more common in young mothers typically in
their early twenties or even their teens.
Usually the chromosomes are normal.
About 40% will develop bowel, bowel dilatation, prenatally
and about 80% will have postnatal complications related
to the gastroschesis.
These include infections
or gastrointestinal complications such
as persistent vomiting, reflux, constipation or fistulas.
So here's a 17 week fetus with a gastroschesis.
You can see the umbilical cord insertion is normal
and adjacent to the cord insertion is a defect in the
abdominal wall through which abdominal contents have
herniated into the amniotic cavity.
Notice that the contour
of these abdominal contents is very irregular
because again, this is not contained
by a peritoneal membrane.
Here's another one again,
showing an irregularly contoured mass protruding from the
anterior abdominal wall.
The umbilical cord insertion is normal
and adjacent to this abdominal wall defect.
And on the 3D, we see how irregular the contour
of this gastroschisis is making it easy to distinguish
from an emale a seal.
Here's an interesting case.
At 22 weeks gestation,
we saw a little bump protruding from the
anterior wall of the fetus.
We had no idea what this was even at 26 weeks gestation,
it looked just like a a little bit,
a little tube protruding from the anterior abdominal wall.
This is the penis of this male fetus.
This is the umbilical cord
and then suddenly at 36 weeks gestation all
of this bowel protruded from the anterior abdominal wall.
So this was a gastroschesis
with a defect in the anterior abdominal wall,
but the abdominal contents did not protrude
until 36 weeks gestation.

Fetal Genitourinary Tract

Well, we'll now move on to the genital urinary tract.
If you look at the images
that we routinely take when evaluating the fetal fetus,
we take images of the kidneys and the bladder.
We do not routinely look at the ureters or the genitalia,
but there are certain situations where it is important
to evaluate these structures.
We look for the kidneys first to make sure
that they're present to exclude renal agenesis.
Then to look at their location
to make sure it's not ectopic.
We move on then to the size
and echogenicity of the kidneys to rule out things such
as dysplasia
or autosomal recessive, polycystic kidney disease.
And lastly, we look at the collecting system
to exclude hydro necrosis.
These are transverse and sagittal views of the fetus.
We can see on a view from the that looks at the posterior
back of the fetus, we see the spine here with shadowing
and we see a kidney on either side of the spine.
In the renal fossa,
the kidney is more hypoechoic than the bowel
and liver in front of it
and it has a bright echogenic capsule
and central echoes in the renal sinus.
On longitudinal view, the kidney has a renal form shape
and by the third trimester as this fetus is,
we can see the hypo coic pyramids separated
by the more echogenic renal cortex.

Amniotic Fluid and Renal Function

We talked about amniotic fluid
and how important swallowing is.
Amniotic fluid is also it's
genital urinary function is also important
for amniotic fluid.
When renal function is absent, then urine is not
produced into the amniotic cavity
and the fetus begins to be surrounded by severe
oligohydramnios with severe and prolonged oligohydramnios.
Changes will occur in the fetus including pulmonary
hypoplasia, abnormal fetal fas
and limb positional abnormalities.

Renal Agenesis

With bilateral renal agenesis, the fetus will be surrounded
by severe oligohydramnios
and on the ultrasound we won't be able
to identify any kidneys or a bladder.
To help us make this diagnosis diagnosis, we will note
that the adrenal glands are oriented longitudinally parallel
to the spine because they're not propped up by the kidneys.
Now, bilateral renal agenesis does cause severe
oligohydramnios and pulmonary hypoplasia,
so this anomaly is incompatible with life.
Here's the case of a fetus with bilateral renal agenesis.
You can see that in this lower picture we have a view
of the abdominal aorta
and we see no vessels on either side, no evidence
of renal arteries.
On a transverse view of the abdomen,
we see severe oligohydramnios
and we see the adrenal gland in the renal fossa
but no kidney and the longitudinal view, we see that
that adrenal gland as is the other one.
They're both oriented parallel to the spine.

Unilateral Renal Agenesis

When there's unilateral renal agenesis,
renal function can be normal.
The contralateral kidney
or the normal kidney will be compensator enlarged
and have normal renal function.
The affected side will have an empty renal fossa
and the adrenal gland will be oriented longitudinally.
You can see this on this diagram, we have the normal kidney
with the normal adrenal gland on that side capping it
and on the contralateral side the adrenal is lower than it
should be and oriented parallel with the vessels
and the spine.
So on ultrasound
what we'll see is when we look at the posterior aspect
of the fetus, we see the normal kidney in its proper
location and no kidney in the contralateral renal fossa.
A measurement of this kidney reveals
that it's longer than normal at almost 5.1 centimeters,
which is even longer than a fetus
or than a neonates kidneys typically is.
And that's because this is compensator enlarged.
When we look at the aorta, we see
that there's only one renal artery coming from the aorta
and when we look in the renal fossa on
that side we see a lying down adrenal gland.

Renal Ectopia

Renal ectopia is when the kidney is in a place other than
the renal fossa.
The most common location is when the kidney is in the
pelvis, but the kidney can also be crossed, fused
to the contralateral kidney
where in it's called cross fused utopia
or both kidneys may be fused across the lower pole
making a horseshoe kidney.
With the pelvic kidney we'll have an empty renal fossa.
Just like with unilateral renal agenesis,
the adrenal gland will be located,
will be oriented longitudinally,
but when we look down in the pelvis
we'll see another kidney.
Also the contralateral kidney will be normally enlarged
normal size, not compensator enlarged.
So here's a fetus who had a pelvic kidney.
When we look at the fetus at the renal fossa,
we see one kidney on one side
and no kidney on the other in
that contralateral renal fossa.
Instead we see a lying down adrenal gland
and then when we look carefully we we were able to see
that right kidney and then next to it down in the pelvis,
the pelvic left kidney.
When we have cross fused dystopia again we have an empty
renal fossa on the contralateral side.
So the adrenal gland will be oriented longitudinally.
The kidney will have an unusual shape.
It may have an L shape and be very elongated
because the contralateral kidney has fused
with the lower pole on that side.
So here's such a case.
When we looked on the right renal fossa,
all we saw was a longitudinally oriented adrenal gland.
So we knew the kidney wasn't there.
And when we moved over
to the left side we saw a large L-shaped kidney.
Here's the left kidney.
It seems to turn a corner as we get towards the midline
because the right kidney has fused with the lower pole
of the left kidney.
Here we see views of the renal arteries.
In this case you can see the renal, the aorta is here.
We have no renal artery on the right side,
but we have the renal artery here
extending to the left side.
And here's a clip showing you the full extent of that
cross fused ectopic kidney.
Now with the horseshoe kidney,
the kidneys are fused at their lower pole
and both kidneys are lower in the abdomen than usual.
So these are what is called tic kidneys.
We'll see these as U-shaped kidneys when we
scan with ultrasound.
So we'll see renal tissue crossing in front
of the abdominal aortic and inferior vena cava.
So here is a case you can see when we look at the aorta,
we see the normal renal arteries.
So we know there are two kidneys,
but when we look at the kidneys more carefully,
we see they have a horseshoe shape.
And here you can see that horseshoe shape
to these two kidneys
because they're fused across the lower pole.
On transverse view we see renal parenchymal tissue crossing
in front of the aorta
and the inferior vena cava At the site of fusion,

Hydronephrosis

We assess the renal pelvis
and kss for dilatation in utero to
diagnose hydronephrosis.
Hydronephrosis is diagnosed whenever there are dilated CAEs
or when the renal pelvis measures seven millimeters
or more from 16 to 20 weeks or 10 millimeters or more
after 20 weeks.
But sometimes we see a little bit
of fluid in the renal fossa
and some of those, some of those fetuses prove
to be abnormal.
And so we classify those as possible hydro necrosis so
that follow-up scans are done.
In these cases you'll see a dilated renal pelvis
that measures four to six millimeters from 16 to 20 weeks
or five to nine millimeters after 20 weeks gestation.
So here's an 18 week fetus where we see
that the renal pelvis measures six millimeters
and this we would classify as possible hydronephrosis,
but this fetus has cile dilatation throughout the kidney
and so this we would classify as definite hydronephrosis.
Now hydronephrosis when first diagnosed in gestation
may change during the course of gestation.
It may resolve, it may be remain
unchanged, but it may progress.
And so follow up is important
because at the first time of diagnosis we are uncertain as
to what the progression might be.
Here for example is a fetus at 18 weeks gestation.
The renal pelvis is on each side measured just under
five millimeters.
This is the level that we would just mention in our report
as possible hydronephrosis.
And here we can see the bladder, normal,
amniotic fluid and the stomach.
But when this fetus came back at 24 weeks gestation,
we now have severe hydronephrosis.
The renal cortex is somewhat echogenic suggesting the
development of dysplasia
and the urinary bladder is dilated with dilatation
of the posterior urethra.
This was a case of posterior urethral valves.

Outcomes of Prenatally Diagnosed Hydronephrosis

We did a study at our institution in conjunction
with Boston Children's Hospital to look at the outcome
of fetuses with prenatally diagnosed hydro nephrosis.
We had almost a thousand fetuses with dilated renal pelvis,
some of which had ectasis and some of whom did not.
And we classified the hydronephrosis as mild, moderate,
or severe based on the degree of dilatation
of the renal pelvis.
So here you can see when it was
before 27 weeks, we called it mild if it was four to seven,
moderate eight to 10 and severe greater than 10.
And then from 28 weeks to term we called it mild at five
to nine, moderate at 10 to 15 and severe at greater than 15.
And we looked at the outcome of these fetuses
and our main goal in looking is at at outcome was to see
how many fetuses actually required surgery
because of their renal anomaly when the
diagnosis was mild in utero on fewer than 10%.
FET of fetuses actually required surgery
for an abnormality when it was mild with ectasis,
14% did require it
and when it was moderate, 21% required surgery
and it was the cases of severe hydronephrosis
where surgery was required in almost two thirds of cases.
The most common reason
or cause of the obstruction that required surgery
is the most common was a ureteral pelvic junction
obstruction followed closely by vesco ureteral reflux
and then a few other unusual anomalies accounted for surgery
and the rest, posterior urethral valves, ureteral vesicle,
junction obstruction, ectopic ureteral,
prune belly syndrome, neurogenic bladder
and cloacal anomaly.
So you can see that ureteral pelvic junction is the most
common cause of neonatal hydro nephrosis that um,
would require surgery.
It's also the most common cause of neonatal hydro necrosis.
It's often a functional obstruction,
so the renal cortex is preserved.
About 30% of cases are bilateral
and it rarely develops into a dysplastic kidney.
So here's a case of repel junction obstruction.
On a transverse view of the kidneys,
we see unilateral dilatation of the renal pelvis
to 13 millimeters.
The coronal view of the kidney shows
that not only is the pelvis dilated,
but we have dilated kcs throughout the kidney.
This is a fetus at 19 weeks gestation
who had minimal dilatation of the renal pelvis
to just under five millimeters.
So in this case we said possible hydronephrosis,
not knowing if this would go away or progress,
but you can see by 32 weeks gestation,
the fetus now had obvious ureteral
pelvic junction obstruction.
The renal pelvis measured almost 14 millimeters
and we see intrarenal CAE dilatation due
to the obstruction at the ureteral pelvic junction.

Vesicoureteral Reflux and Primary Megaureter

Vesco ureteral reflux results from an abnormal insertion
of the ureter into the bladder.
The ultrasound findings are classic with a hydronephrosis
and hydro ureter,
but the ultrasound findings are identical
for another pathologic process
identified in ureter in utero, namely primary mega ureter.
This is when you have an a peristaltic segment
of the distal ureter
and thus you have dilated the dilated kidney
and ureter just like with vesco ureteral reflux.
So the best we can do in utero is to diagnose hydronephrosis
and hydro ureter and whether it's primary mega ureter
or vesco ureteral reflux will have
to be determined after birth.
So here's a fetus with hydronephrosis
and hydro ureter at 17 weeks gestation on a transverse view
of the kidney, we see the renal pelvis is dilated
to almost seven millimeters
and on a longitudinal view we see intrarenal dilatation
and dilatation of the ureter from the kidney down
towards the bladder.
This fetus has a similar diagnosis at 25 weeks gestation,
the renal pelvis is dilated to 14 millimeters.
Then the clip, you can see
that there's intrarenal dilatation,
but in addition there's a markedly dilated tortuous ureter
extending from the kidney to the bladder.

Renal Duplication

Renal duplication can occur in these cases there may be two
ureters arising from the kidney instead of one
and it is common in such situations
for the upper pole ureter to become dilated
and obstructed as we see in this example.
So in those cases
what we'll see is we'll see fluid in the kidney.
That will be the,
we'll see more fluid in the upper pole than the lower pole
because the distal ureter is dilated
and sometimes that distal ureter from the upper pole
connects into a ureteral seal.
So here's an 18 week gestation
where we see in looking at the kidney
that the upper pole is more dilated than the lower pole.
When we look in the mid abdomen,
we see a dilated tortuous ureter
and when we look at the level of the bladder,
we see two cystic structures
because one represents the ureter seal
and the other, the urinary bladder.

Renal Dysplasia

Renal dysplasia occurs from obstruction
of drainage from the kidneys and it presents in two forms.
The dysplastic kidney may be thin
and echogenic with minimal parenchyma
and it may have the appearance of hydronephrosis
and this type of dysplasia typically results from
obstruction that occurs after 10 weeks gestation
or from incomplete obstruction.
The other form of renal dysplasia is a multicystic
dysplastic kidney.
This results from early complete obstruction of the kidney.
The sonographic appearance is very different
with renal dysplasia from late obstruction.
The kidney shows dilated CAEs, hydro nephrosis
and a very thin cortical mantle as we see here.
And the renal cortex that it does remain
or the renal parenchyma is very echogenic.
So here we have a fetus with posterior urethral valves,
bilateral hydronephrosis.
You can see it on the still image as well as the clip.
And then mark thinning of the renal cortex here
and here with increased echogenicity.
All of this due to dysplasia.

Multicystic Dysplastic Kidney

On the other hand, a multicystic dysplastic kidney presents
as a kidney completely replaced by a large multicystic mass.
These are typically unilateral, which is a good thing
because when it is bilateral it's incompatible with life
and this is the typical appearance
of a multicystic dysplastic kidney.
In the renal fossa we'll see a collection of cysts
with a little if any solid component.
So here on transverse view is that collection of cysts.
In the other renal fossa we have a normal kidney.
On sagittal view we see a collection of cysts
and typically the size
of the multicystic dysplastic kidney is much bigger
than a normal kidney.
Note that the amniotic fluid around this fetus is normal
and that's because the contralateral kidney is normal
and replenishing the amniotic fluid with urination.

Autosomal Recessive Polycystic Kidney Disease

Autosomal recessive, polycystic kidney disease is a disease
of the kidneys that leads to renal failure
and hepatic fibrosis.
Overall the prognosis is quite poor,
but the severity does,
the prognosis does depend a little bit on the severity
of renal involvement at birth.
On ultrasound with this type of anomaly,
we have enlarged echogenic, kidneys, oligohydramnios
and absence of the bladder bladder in those cases
where the renal function is completely impaired.
So here's a 33 week gestation.
Notice that there's no amniotic fluid around this fetus.
On a longitudinal view, notice
that the kidneys are enormous.
They measure more than eight centimeters on each side while
they retain their renal renal form shape.
They do have increased echogenicity.
Notice that not only are they enlarged from top to bottom,
but side to side as well.
On this transverse view of the abdomen, we see
that the kidney fills the abdomen anterior
to posterior as well.
This fetus also has autosomal recessive polycystic kidney
disease, but in this case we actually could see the
microcysts inside the kidneys.
We see all these very small cysts filling the
renal parenchyma.
We also see very large kidneys.
This fetus also had a hepatic cyst, a finding
that's associated with this type of disease.

Urinary Bladder

Now we also look at the urinary bladder first
to see if the bladder is present
because if it is present, that does indicate
that there is some renal function.
An absence of the bladder would indicate absent renal
function, which can be seen with bilateral renal agenesis
or bilateral multicystic dysplastic kidneys
or autosomal recessive polycystic kidney disease.
Now the bladder may also be,
may not have fluid in it when there's extraphy
and the bladder is averted.
When we see the bladder, we assess its size to look at
to see if it's enlarged, such as
with posterior urethral valves.
Normally we should see the bladder in the pelvis
or lower abdomen by the end of the first trimester
as a fluid-filled ancho structure as we see here,
and it's labeled by the arrow
with posterior urethral valves.
The bladder is markedly enlarged.
There will be hydronephrosis and hydroureter
and we may have severe oligohydramnios.
This anomaly results from obstruction in the in the
urethra at the level of the posterior urethra
and it's the second most common cause
of hydronephrosis in the neonate.
This anomaly only affects male fetuses.
The characteristic appearance
of posterior urethral valves is a dilated bladder
and dilated posterior urethra.
That's sometimes been called the keyhole appearance.
You can see in this case of posterior urethral valves,
we have the dilated bladder
and then we have a po, a protrusion
of fluid into the upper urethra
and that represents the dilated posterior urethra.
In this case. We can also see the very dysplastic,
small echogenic kidney associated with this abnormality.
This fetus also is posterior urethral valves.
It has the classic findings of severe oligohydramnios,
a dilated bladder, a dilated posterior urethra
and dysplastic kidneys with hydro nephrosis.
You can see the hydronephrosis here
and the echogenic cortex around the outside

Prune Belly Syndrome

Prune belly syndrome has similar ultrasound findings except
that the amniotic fluid will be normal.
This syndrome occurs because of abnormal
or absent development of the abdominal musculature
and abnormal smooth muscle will have dilated bladder,
dilated kidneys and dilated ureters.
And we may see the dilated urethra
that will mimic a posterior
that the upper urethra will mimic posterior urethral valves.
But you may also see a dilated penile urethra
because these fetuses still can produce am urine,
they can replenish the amniotic fluid
and so the amniotic fluid volume may be normal
and the development of urine ascites, which may occur
with posterior urethral valves does not
occur with prune belly.
So here's a fetus with prune belly syndrome.
Notice that there is amniotic fluid around this fetus,
but we can see a dilated bladder.
We can see that in addition the kidneys are dilated
but the renal cortex is still has some thickness to it
because it's not dysplastic.
This is the penis. We can see fluid in the penile urethra.
Another classic finding with prune belly syndrome.

Bladder Exstrophy

Now bladder extraphy is when there's a defect in the
anterior abdominal wall at the level of the bladder
and the bladder is exposed to the outside of the fetus.
It may even be Ted that is turned inside out
and pushed outside of the fetal abdomen.
Extraphy is associated with genital abnormalities,
so this is a time we would look at the genital tract as well
on ultrasound with extraphy, we'll have non visualization
of the bladder if the bladder is exteriorized,
but we'll have normal amniotic fluid volume
and normal kidneys.
So that's how you know that the bladder is still able to
transport urine out to the amniotic fluid.
We may see a lower abdominal mass if the bladder protrudes
from the anterior abdominal wall.
And so here is such a case here is a view, uh, sagittal view
of the fetus where we see a normal umbilical cord insertion.
And then just beneath it we see a small mass protruding from
the anterior abdominal wall.
This fetus had normal appearing kidneys
but no bladder could be found in the pelvis.
Here is another case we see protrusion from the anterior
abdominal wall below the cord insertion.
And here's the baby at birth with the averted bladder
and the bifid scrotum.

Ambiguous Genitalia

Well I did mention that sometimes it's important
to look at the genitalia, particularly with things such
as when you have bladder extrophy and that's
because we would wanna diagnose ambiguous genitalia
if it is diagnosed.
We then wanna find out what's the karyotype
because depending on the karyotype will help figure out
what the prognosis is for the fetus.
So ambiguous genitalia is associated with a variety
of syndromes as well as bladder extraphy.
So here is a fetus who proved to have a male karyotype
who had ambiguous genitalia.
You can see that there is some form of a fallous protruding
between two soft tissue structures.
And so this could either be an enlarged clitoris
or that's located between the labia
or a small PHUs that's located between a bifid scrotum
where the testicles are not descended.
This proved to be a male fetus.
Here's another one, a 23 weeks gestation
that we've evaluated with 3D ultrasound.
You can see that the PHUs is pointing downward,
that the scrotum is bifid and splayed to either side.
And here is another ambi fetus, male fetus
with ambiguous genitalia.
Again, you can see the PHUs located between the two sides
of the scrotum rather than superior to it.
Here you can see it in the same kind of view
with the PHUs here, then the two parts of the scrotum
and by 33 weeks gestation.
Now the testicles had descended
and we have a bifid scrotum with the two sides separated,
not fused together.

Conclusion

Well, I hope I've given you a good run
through the gastrointestinal tac tract
and genital urinary tracts
and I hope you find this useful in your practice.
Thank you.