This is a screenshot
of the title page
of the aforementioned paper.
It was published in 2013,
a review article.
And this is what we're going
to talk about today in today's
presentation.
In section one,
we deal with definitions
between SGA and IUGR--
that
is small for gestational age
and intrauterine growth
restriction.
In section two,
we talk about the screening
methods for these two conditions
and possible ways in which they
can be improved.
In section three,
we talk about the management
and section four, we round off
with a summary of the points
which we find could have been
better in this article.
SGA is defined as a field birth
weight of less than 10%
of the total population.
And that is confirmed
by ultrasound.
Other sources have advocated
the use of 5% or 3%.
But basically it is an arbitrary
cutoff point at the moment,
whereas IUGR,
Intrauterine growth restriction,
is basically any condition
any in-utero condition,
which restricts the growth
of the fetus
to its full predicted age.
The causes can be broadly
classified as maternal,
placental, or fetal.
And on the slide,
you'll see some examples.
Current definitions tend to use
these terms
quite interchangeably and more
accurate
use would say that IUGR is part
of SGA
and this is the basis
for the author's paper
in which he goes about trying
to challenge
these current definitions.
The author goes on to say
that the term should be distinct
and should define them
differently as such
because this definition does not
make a distinction among infants
who are constitutionally small,
growth restricted small,
and not small birth, growth
restricted relative
to their potential.
As an example, as many as 70%
of fetuses who way
below the 10th percentile
for gestational age are small
simply
because the constitutional
factors such as female, sex,
or maternal ethnicity, perry,
or BMI.
They are not at high risk
of perinatal mortality
and morbidity
but
under the current definitions,
they would be defined as IUGR.
One further point is that if you
go by the 10% criteria for small
for gestational age,
if you take it for,
let's say, this country and then
you go to another country,
you might find
that
under the same classification
you could end up with 23%-- one
of the papers that we cited.
So obviously there needs to be
few changes in definition.
Now on the diagram,
you'll see three
different examples of how
a fetus could be classified.
The first example is the fetus
is not small, but it is growth
restricted.
For example, it
is possible for a fetus
to be growth restricted,
but not be in the less than 10%
of estimated fetal weight.
On the other hand, a fetus could
be just constitutionally small
because of, let's say,
parental factors
or other factors,
such as sex or ethnicity.
Finally, you could always have
a fetus that is both growth
restricted and small
and the author says that this
calls for a need for better
definitions.
Finally, the author goes on
to summarize his suggestions,
like how you see on the page
here.
The main thing is he still
decides to stick with just two
definitions
for this current problem
that we have.
So then he gives examples of how
these definitions can still
work.
For example CMV can still
be relatively easy classified
as IUGR still.
He admits that there will be
difficulty with some definition,
such as aneuploid fetus.
You might think that it might be
easily classified as SGA,
but the problem is aneuploid
fetuses are also correlated
with dis-functional placentas.
You could say that that is
because of the aneuploidia
itself and therefore you could
classify it as IUGR.
So the question is, do you
classify it as just SGA
by itself or do you classify it
in the middle right
there as SGA superimposed IUGR.
And this is one of the critiques
that we have of this paper,
is
that
under the current definitions
you do run into a lot
of problems.
And the main thing is things
which are even harder
to classify,
such as fetal alcohol syndrome.
It can't easily be classified
under the current definitions
that we have.
And we're surprised
because there are
other classification systems
currently in use.
And we'd like to propose one
which is probably better
than the current suggestions
by the author.
Rather than looking at just
the size of a fetus
or its possible causes,
we feel that there might be
better definitions in existence.
For example, one which looks
at also how likely the fetus
will benefit from ante natal
intervention
and whether or not
their outcomes are modifiable.
By doing this, we can avoid
subjecting fetuses
to unnecessary interventions.
So the diagram to your right,
you see that of all this year's
fetuses,
40% are healthy small fetuses,
meaning that they are
constitutionally small,
as well as 20% of SGA fetuses
are intrinsically small, which
means either they have CMV
infections, fetal alcohol
syndrome, or a neuploidy.
By classifying it like this,
we are taking a more
clinical approach
and we're saying
that these fetuses do not need
intervention.
And we feel that this is
a better approach to OB/GYN
practice.
And finally the 40%,
the darker 40% that you see
there,
which is growth restricted
SGA, now we've identified them
as possibly benefiting
from intervention and therefore
we are no longer concerned
whether or not FAS should be
classified as SGA or IUGR.
We are just sure that it is not
likely to benefit
from intervention
and we will not intervene.
Moving on, we will now talk
about current issues
in screening methods.
For example, we talk about how
to screen for fetal growth
abnormalities,
the current practices,
the accuracy of final height
measurements
and ultrasound and finally
the challenges in terms
of antenatal testing, doppler
ultrasound,
and timing of delivery.
For the remainder
of this presentation
SGA will be referred
to as those fetuses which we do
not feel
would benefit from intervention
while IUGR are those that will
be, for the sake of simplicity.
Now moving on, the author's
suggestions to improve
the screening methods
are quite effective.
You see on your screen,
there are
several different factors which
play a part in an SGA or IUGR
fetus, things
such as maternal age, height,
weight, paternal height
and weight,
race, ethnicity, so on, so
forth.
These all play a part
in determining whether or not
a fetus is classified as SGA
or IUGR.
Now the author makes
a strong point in saying
that if we are able to account
for these factors,
then we are better
able to arrive at growth curves
which are more
predictive
of percentile estimates.
And by doing so,
we will be able to tell
whether or not intervention is
likely to benefit outcome.
We'd also like to add
that the recent literature is
in agreement with the author's
viewpoints.
There have been several studies
trying to incorporate all
these different predictive
values into some sort
of algorithm.
The idea is one day we'll
be able to enter all
the patients particulars
into a computer, and it will be
able to say whether or not
the fetus is indeed SGA or IUGR.
I will not discuss
about the management
of SGA/IUGR.
I
If SGA/IUGR is suspected,
the author suggested performing
antenatal testing, which
includes non-stress tests
and biophysical profile.
The biophysical profile in turn
includes fetal movement, tone,
breathing, AFI, and fetal heart
rate.
In addition, the author also
suggests performing
serial ultrasound growth scans
as a form
of fetal and anatomic survey,
as well as doppler blood flow
studies
to assess the amount of blood
flow to the fetus.
These suggestions are in line
with the current literature.
However when we did a literature
search, there are studies that
also support fetal karyotyping
to screen for karyotypes types
such as Trisome 21 and 18,
which may lead
to anatomical defect
in the fetus and has SGA/IUGR.
In addition, another study
suggested performing
maternal serum examination
for infection
such as corneal immunitis.
As part of antepartum
management, other literatures
have suggested repeating
ultrasounds one to two times
a week if normal,
but more frequently if result is
abnormal.
Another studies suggests
that glucocorticoids be given
to the mother for preterm
gestations
to aid in fetal maturity.
And of course, should the cause
of SGA be found, treatment
should be given to the mother
immediately.
For example, control
of hypertension in the mother,
and treatment of CMV
with antiviral hyperimmuno
globulin therapy.
There is, however,
an important question that
remained
elusive to obstetricians
even to today.
The key question is, how will
the neonate do
at a current gestation age
versus what is the ongoing risk
over the next week and outcome
if he achieves another week
of gestation.
There is however
little consensus
about the optimal time
of delivery of the fetus.
This is partly
due to the insufficient evidence
from randomized control trial.
If we guess to the delivery
timing of fetus
in the setting of SGA,
the author did however mention
some determinants that could
assist obstetricians into making
a delivery decision.
For example, the author
suggested doppler ultrasound
scanning, particularly looking
at the umbilical artery
as a determinant
for the decision
to deliver a fetus.
As you can see from the chart
here, should the ultrasound scan
show normal blood flow,
the author suggested
ongoing fetal assessment
one to two times per week
and expected management
to achieve fetal maturity.
However if there is
abnormal blood flow,
such as reverse end-diastolic
blood flow, the author suggested
delivery
at any viable gestation age.
If the abnormal blood flow is
in the form of increased
systolic or diastolic ratio
or absent diastolic blood flow
and the fetus is at least 24
to 25 weeks gestational age,
the author suggested
expectant measurement in view
of high risk and more
frequent evaluation
is indicated.
If the gestation age is more
than 25 weeks, the author
suggested weighing the risk
and benefits of delivering
the fetus.
The author also suggested
amniotic fluid index
as a determinant
for the delivery timing.
Although the AFI is
a crude measurement of mid
to long term placental function,
the author suggests earlier
delivery of fetus,
if oligohydramnios in a setting
of suspect IUGR.
In addition, there is also
a study that the auto quoted
that suggested
that every extra week
of intrauterine maturation
for the fetus
put twice the risk
of stillbirth.
Therefore, the recent benefit
of delaying delivery
may be complicated
with an increased risk
of stillbirth,
and this is an important factor
for all obstetricians
to take note.
This is a list
of relevant literatures
that we found on Pat Net.
Basically, there are
many different studies that
attempted to scrutinize
the different factors that may
improve the outcome of the fetus
in the setting of SGA.
For example, there was a study
that suggested
every single intrauterine day
improved the survival of fetus
by 1% to 2%
between the gestational age
of 26 to 29 weeks.
However, the issue is that there
is no breakthrough study that
has sufficient evidence to guide
the delivery of SGA fetus.
This is perhaps attributed
to the difficulty of performing
randomized controlled trial
in this area.
We did however manage to find
an author that tried to use
several parameters
such as abdominal,
circumference, growth rate,
biophysical profiling
to classify the severity
of IMGR.
In this study,
Harman and Baschat basically
used parameters as mentioned
earlier to stratify fetus
in IUGR setting into five
different gradings for which
each grading had a suggested
course of action to be taken.
For example, scenario one
is the least severe
and therefore expected
management is advice, where
as scenario five is the most
severe
and has delivery as soon
as possible is advised.
We feel that perhaps such a
graduated approach to IUGR
may be helpful to assist
obstetricians in judging
this issue.
Finally, I would like to provide
a summary of critique
for this article.
The author did point
out several important points.
For example, he recognized
the importance to differentiate
between SGA and IUGR,
and also proposed delineation
and better academic definitions
between SGA and IUGR.
In addition, he also attempted
to normalize measurements based
on multiple factors
such as parents height, weight,
ethnicity to remove confounding
variables in the diagnosis
of IUGR.
However, there are areas where
the author failed to discuss as
well.
For example, although he did
mention key management steps
of SGA, he omitted discussion
on categorization, profiles,
and graduated management steps
based on BPP and doppler
ultrasound,
as well as antepartum management
measures.
In addition, although he did
discuss the dilemma
between prematurity
and stillbirth,
he did not suggest
a clear framework on handling
the issue, thusly he did you not
mention
about the important randomized
trials that has been done so far
and the inconclusive results
from these trials.
