00:01
Welcome.
00:03
In this talk, we're going to
be discussing gastroschisis,
which is part of
gastrointestinal pathology.
00:09
You will see we have a lot to talk
about when we talk about GI pathology.
00:14
It's more or less from
the top to the very bottom
with a lot of other organs
attached on the side.
00:21
In some of these initial
talks on GI pathology,
we're going to talk about
anomalies, maldevelopment,
and gastroschisis
will top the list.
00:29
So gastroschisis is a full thickness
defect of the anterior abdominal wall.
00:34
And the intestines or some
of the viscera such as liver
will protrude outside but there will
be no membrane or sac covering this.
00:42
This is to be distinguished
from omphalocele
that we're going
to talk about next.
00:47
So the defect is often also just to the
right of the umbilical insertion site.
00:52
And we'll talk in a moment
about developmental biology,
so that will explain why there's this
typical location for gastroschisis.
01:00
This roadmap,
we will see over and over again,
throughout all of the talks
on gastrointestinal pathology.
01:07
And we'll use this again here where
we'll talk about epidemiology.
01:11
Then we'll go through
pathophysiology,
we'll do clinical presentation,
diagnosis and monitoring,
and management and prognosis.
01:19
So first, for epidemiology.
01:21
It's a relatively rare
prevalence for this disease.
01:24
So a gastroschisis occurs in roughly
3-4 babies born out of 10,000 births.
01:31
And there's a similar incidence whether
the baby happens to be male or female.
01:36
In 10% of the cases, however,
gastroschisis is also associated
with anomalies outside
of the GI tract.
01:41
And this raises the specter as we'll see
in a moment of basic genetic defects.
01:47
There's also a very higher risk of
preterm delivery and pregnancies
when there's gastroschisis.
01:52
So about a quarter of
babies with gastroschisis
will have earlier
preterm delivery
that's compared to
those who do not
which is about 5% of the total.
02:02
So there are a number
of maternal risk factors
that put babies at risk of
developing gastroschisis.
02:08
A very young mom, for example,
will be a good reason.
02:12
Women who are pregnant in
her less than 20 years of age
have an increased risk for
delivering a baby with gastroschisis.
02:18
Also very low body mass index.
02:21
So someone who just doesn't
have a lot of meat on her bones.
02:25
We will also have increased risk
associated with certain ingestion
such as exposure
to cigarette smoke,
or the intake of aspirin and ibuprofen,
nonsteroidal anti-inflammatory drugs.
02:38
In addition, the intake of
decongestants can be associated
with gastroschisis
for unclear reasons.
02:45
Let's get into the
pathophysiology.
02:48
So we're looking here at a very
early, about four weeks embryo.
02:54
It doesn't look like much.
02:55
This is a transverse slice,
at the top is going to be anterior
at the bottom is
going to be posterior.
03:04
The yellow is yolk sac.
03:06
The green is amniotic fluid,
and you see a lining of ectoderm
around that and mesoderm as well.
03:12
It will now go through
a variety of folds
that allow us to finally
get the developed embryo
with now an abdominal
peritoneal cavity
that has in the case of
gastroschisis, a lateral wall defect.
03:32
Here we're seeing a
lateral view from the side,
showing the similar
kinds of folding,
and it can be very complex.
03:38
So we're gonna show them side by side
with a transverse and a lateral view,
seeing the various
folds that occur.
03:46
And you'll see looking
at the transverse image,
we're going to have a defect that
is going to be our gastroschisis,
and on the right you will also
see where the bowel is herniating
through the abdominal wall.
03:59
So with regard to
the pathophysiology,
and why this defect typically
occurs on the right-hand side.
04:06
Let's get into some of
the vascular development
that happens during
differentiation.
04:11
The umbilical veins in the
developing placenta and fetus
are originally bilateral.
04:16
They drain into the sinus venosus which
will eventually become the right atrium.
04:21
In the second
month of gestation,
there is complete regression
of the right umbilical vein.
04:26
However,
the left umbilical vein persists,
connecting to the ductus venosus
within the developing liver.
04:33
The ductus allows the shunting of
oxygenated blood past the liver,
and into the nascent
inferior vena cava.
04:41
While it is patent however,
the right umbilical
vein is really important
for supplying the
nutritional building blocks
that allow the normal right
sided abdominal wall development.
04:52
If however, the right umbilical vein
decides it's going to close prematurely,
the abdominal wall will
be incompletely formed.
04:59
That will obviously then lead to the
gastroschisis that is seen at birth.
05:04
And now you understand why there's a
right sided predominance of these lesions.
05:10
Let's come to the
clinical presentation.
05:13
So it's not subtle in most cases, there
is a paraumbilical abdominal wall defect,
usually to the right side of the
umbilical cord insertion site,
and there's no
membrane covering that.
05:25
The abdominal wall defect is
usually something less than 4 cm.
05:30
There are complications associated
with this, as you might expect.
05:33
So with this part of the bowel
being outside of the abdominal wall,
during development,
there's reduced bowel motility.
05:41
And there's also
reduced bowel absorption
due to the unprotected intestine being
exposed to irritating amniotic fluid
and we tend to lose fluid into that
developing GI tract because of irritation.
05:56
There's also related vascular compromise
caused by the bowel's herniated,
so we will may not get
normal bowel development.
06:05
And as a result of that intestinal
atresia, so loss of part of the GI tract
is seen in about 5% to 25% of
newborns with gastroschisis.
06:15
So the complications overall
involve intestinal stenosis,
that means that we have obliterated
the lumen of the intestine,
you may have short bowel because
it's just not developing normally,
you may lose portions of the
bowel, intestinal atresia,
you may have perforation,
or you may have necrosis or volvulus
volvulus, literally meaning
tying the bow into a knot.
06:38
As a result of this exposed bow,
you also have an increased risk
for gastrointestinal infections.
06:43
And there's a very high risk for
in-hospital mortality and complications,
which means we really need to
mobilize the clinical teams
when we identify this at birth.
06:53
Diagnosis and monitoring.
06:56
So ultrasonography is going to be
our best friend in diagnosing this.
06:59
And most of the time, we make a prenatal
diagnosis often as early as 14 weeks,
but usually around 20
weeks or mid gestation.
07:08
The findings include oligohydramnios, which
means a reduced amount of amniotic fluid.
07:14
And then we will also
occasionally see other organs
that have herniated
such as the liver.
07:19
If there are more organs
that are herniated
that obviously increases
the overall risk.
07:24
This is just an ultrasound,
and you can see the head to the left,
and we have a green arrow
pointing to a very obvious defect
in the abdominal wall with
loops of bowel sticking out.
07:35
When this is identified,
we will also in most cases
do fetal genetic studies because
there is an underlying genetic basis
for a number of these
cases of gastroschisis.
07:47
And especially if we want to
identify potentially other
complications that will
affect long-term management.
07:56
In terms of that management
and the overall prognosis,
so the message is this is
going to be okay in most cases.
08:03
It does require that we get together with
the maternal fetal medicine specialists,
neonatologist and
the pediatric surgeon
and we would normally having identified
this in advance recommend delivery
in a center that has terrific
neonatal care resources.
08:19
For uncomplicated gastroschisis,
that means nothing else is herniated
besides a few loops of bowel
that is not a contraindication
to vaginal delivery.
08:28
But if we have liver
herniation as well.
08:31
Babies should be
delivered by cesarean.
08:34
They need to go into
neonatal intensive care.
08:37
And we want to reduce intestinal
injury and reduce fluid loss
because of the loops of
bowel that are exposed.
08:44
We protect that exposed bowel by
wrapping it with sterile saline dressings
covered with a plastic wrap
to limit the loss of fluid.
08:51
And in some centers, you may even lower
the entire lower half of the neonate
into a plastic bag that will protect
all of the lower bowel perfusion.
09:02
In our neonatal care centers we will
reduce that intestinal injury.
09:06
We will do fluid and
electrolyte resuscitation
and we will give prophylactic
broad-spectrum antibiotics
to limit the possibility
of infection.
09:15
And finally, to treat this,
initially we will
decompress the bowel.
09:20
So we don't want anything
going through those loops about
until we can
surgically correct it.
09:26
We'll maintain airway, we will give
respiratory support as necessary.
09:30
And then ideally surgery is
performed within hours of birth.
09:35
And that's to minimize intestinal
injury and during that surgery,
we will usually extend
the defect a little bit
so that we are not poking the
bowel through a little tiny hole.
09:47
We'll make the hole
a little bit bigger.
09:49
In general, surgical closure,
once we have reduced the bowel,
pushed it back inside will be successful
in greater than three quarters of cases.