"Probable IUGR"

OK, Ericka. Let's make it +/- 20%. That gives a 95% CI of 1836 grams to
2755 grams. With the 10%tile for a 38 week fetus at 2714 grams, you're
saying there is an outside chance the fetus is 41 grams over the cutoff
for SGA. Either way, fetal surveillance is justified in this case. As a
clinician, you can't just say "There's an outside chance this baby
might be at the 12th percentile, so let's don't investigate any
further."

And yes it is possible that an inexperienced sonographer did the scan -
or maybe even a tech who isn't a boarded sonographer - and maybe the
estimate is off by more than that. Maybe there was a typo on the report
and it should have said "15 lbs 1 oz," and they missed the "1" key when
they were typing it up. None of that really changes the appropriate
management though. Based on the information we have, fetal surveillance
is appropriate here.

Also, even if error is 10-15 percent, is that error evenly
distributed over different weight fetuses?

I haven't seen this studied systematically, but my experience is that
weight estimates are less accurate for larger babies and more accurate
for smaller babies. When clinicians recommend c/section for a u/s
estimate LGA, I cringe. When we recommend fetal testing for a u/s
estimate SGA, there's not much to cringe about.

And actually, I think you are being just a little bit argumentative.
The gist of my post stands. The fetus is probably (but not definitely)
small for gestational age. There is error in ultrasound estimates of
weight, but that's not really the most important thing to think about
here. The most important things to think about are what are the
implications if the baby is small, and what should be done about that?
Most SGA babies turn out fine. Some of them are poorly perfused, so it
makes sense to do fetal surveillance and deliver if there is evidence
of placental insufficiency. The doctor is being a weenie for not
explaining this better and for lashing out at the patient.

And actually, I think you are being just a little bit argumentative.
The gist of my post stands. The fetus is probably (but not definitely)
small for gestational age.

actually from all the rest of the information I don't even think there is
that much chance the baby is small for gestational age, I know fundal height
measurements are not perfect, but a steady increase in fundal height
measurements is very encouraging, could still mean a small baby, but not an
IUGR baby. With my probable IUGR baby, fundal height was spot on, 32cm at 32
weeks, then never increased beyond 33cm. With my 2nd baby my fundal height
measurements were all over the show, often 4cm behind, but steadily
increasing, so there was no concern.

I do agree that monitoring is prudent in this case, I just would be
surprised if this baby actually pops out at small for gestational age,
5lb1oz doesn't even sound that small for 36 weeks, though I don't know
exactly where it is on the centiles.

Anne

alath wrote:
OK, Ericka. Let's make it +/- 20%. That gives a 95% CI of 1836 grams to
2755 grams. With the 10%tile for a 38 week fetus at 2714 grams, you're
saying there is an outside chance the fetus is 41 grams over the cutoff
for SGA. Either way, fetal surveillance is justified in this case. As a
clinician, you can't just say "There's an outside chance this baby
might be at the 12th percentile, so let's don't investigate any
further."

No, no--I'm not saying that surveillance isn't warranted.
I'm just suggesting that the odds she really needs to be worried
in light of the whole situation is probably quite low and that
there's a pretty substantial amount of room for error. Even
with a 95 percent confidence interval, there's a 5 percent
chance that the measurement is outside that range. I've just
got a sneaking suspicion that something is fishy with this one.
That doesn't mean that one shouldln't continue surveillance.
I think that would be irresponsible. I just think that it
smells a bit fishy in this case and that the OP shouldn't
be anywhere near as worried as her doctor is implying.

Also, even if error is 10-15 percent, is that error evenly
distributed over different weight fetuses?

I haven't seen this studied systematically, but my experience is that
weight estimates are less accurate for larger babies and more accurate
for smaller babies. When clinicians recommend c/section for a u/s
estimate LGA, I cringe. When we recommend fetal testing for a u/s
estimate SGA, there's not much to cringe about.

Hmmm...again, not a systematic search, but here are the first
few things I came across:

http://tinyurl.com/cyg5y
Which finds only 75 percent of measurements within 10 percent of
birthweight with BPD-AC-FL and worse results with Shepard (though
AC-FL, which is apparently what they used for the OP close to
BPD-AC-FL) for an IUGR population.

http://tinyurl.com/arhrz
This one found Shepard at 72 percent for low birthweight babies

And one of the earlier ones I posted said that estimates were
more inaccurate with Shepard for lower birthweights.

Now, again, I don't want to overstate. Obviously IUGR can
be a real issue, and even if we don't have the best tools
to diagnose it, we have to work with what we have.

I recall that last time I was looking, it was in the context
of macrosomia, and the studies seemed to indicate that u/s
was better at detecting macrosomia than SGA or IUGR, *BUT*
(as you say), diagnosing macrosomia just led to more
interventions with worse outcomes while diagnosing SGA or
IUGR was more clinically relevant. So, even if it is less
accurate for small babies, it seems more important to
try to diagnose it.

And actually, I think you are being just a little bit argumentative.
The gist of my post stands.

Sorry, I agree with your main points that surveillance
is warranted and the doctor is lacking in bedside manner (jerk,
I think you said ;-) ). I was just reacting to the bit about
the 95 percent CI being within 10-15 percent.

The fetus is probably (but not definitely)
small for gestational age. There is error in ultrasound estimates of
weight, but that's not really the most important thing to think about
here. The most important things to think about are what are the
implications if the baby is small, and what should be done about that?
Most SGA babies turn out fine. Some of them are poorly perfused, so it
makes sense to do fetal surveillance and deliver if there is evidence
of placental insufficiency. The doctor is being a weenie for not
explaining this better and for lashing out at the patient.

Certainly we agree on that, and I worry about the
doctor's future behavior given his past behavior. I also
wonder if it's *just* a matter of bedside manner, or if he
really *believes* that the situation is as hopeless as he
is portraying. If he believes it, that is also cause for
concern, as that could lead to him pressing for intervention
*without* additional confirmation from surveillance that there
really is an issue to worry about.

Best wishes,
Ericka

I recall that last time I was looking, it was in the context
of macrosomia, and the studies seemed to indicate that u/s
was better at detecting macrosomia than SGA or IUGR, *BUT*
(as you say), diagnosing macrosomia just led to more
interventions with worse outcomes while diagnosing SGA or
IUGR was more clinically relevant. So, even if it is less
accurate for small babies, it seems more important to
try to diagnose it.

I saw somewhere, sadly can't recall where that diagnosing IUGR actually
gives worse outcomes, problem is, it didn't say what it meant by outcome,
because severe IUGR causes death, which is clearly not a good outcome. But
the gist was with the vast majority of IUGR they will be fine waiting for
labour to start naturally, so you avoid all the risks of induction. But also
that any intervention after the birth was rarely a help, for example, I
think had it been decided that DS was IUGR, even though his birthweight was
over 2.5kg, we would probably still have been in transitional care, which
would have meant force feeding, every 4 hrs, or maybe 3, not sure what the
protocol is, but DS slept for the first few days and rarely fed, however was
well above his birth weight at 2 weeks, so was fine, but had he been treated
as different, he would almost certainly have been supplemented with formula,
which could have led to the failure of breastfeeding. The more I learn about
IUGR, the more I am convinced he really was IUGR, but as there are no
maternal risk factors, I'm glad he was not diagnosed, we breastfed
sucessfully and there was no extra concern in my 2nd pregnancy.

Anne

The more I learn about
IUGR, the more I am convinced he really was IUGR, but as there are no
maternal risk factors, I'm glad he was not diagnosed,

I think it is important to distinguish between IUGR and SGA - which
people rarely seem to do. It is a difficult distinction to make
clinically and prospectively, but there is a clear conceptual
distinction. SGA simply means that the baby is small for age - less
than the 5th or 10th percentile depending on whose definition you use.
The diagnosis of SGA leaves open the possibility that the baby is
totally normal, with no pathology and probably little if any increased
risk of adverse outcome. The diagnosis of IUGR means that the baby is
SGA, and that there is a pathological cause for the baby's small size.
If you think about some condition or pathology that is severe enough to
interfere with the baby's growth, it is easy to see how that could be a
threat for adverse outcomes.

The problem, of course, is trying to distinguish SGA from IUGR before
the baby is born. A small baby with normal fluid, normal NST findings,
normal symmetry, normal anatomy, normal behavior, normal blood flow in
the cord, and a normal healthy mom is probably a small-but-normal baby
- SGA but not IUGR. Show me an SGA baby with anhydramnios,
nonreassuring testing, low biophysical score, reverse end diastolic
flow on doppler velocimetry, and a chronic hypertenisve mom, and I am a
lot more concerned. The latter baby is in danger and needs to be
delivered. The former probably does not.

It sounds to me like your son was probably SGA but I see no evidence of
IUGR.

It sounds to me like your son was probably SGA but I see no evidence of
IUGR.

no no no no, all the evidence is IUGR, he wasn't even technically SGA as
though he was 5lb13oz, he was also born at 37+4. The evidence for IUGR is
everything being entirely normal until 32 weeks, fundal height spot on,
growth scan putting him at 75th centile, then minimal maternal weight gain,
minimal increase in fundal height, birthweight 25th centile for gestation,
enlarged fontanelles, appearance at birth and several other things I can't
recall right now.

Having now had another child the way I expanded in the last 4 or so weeks in
the way that everyone had told me would happen first time was amazing, we
didn't expect her to be so big, but she was 8lb8oz, with a head
circumference only 4mm bigger than DS, she was in proportion, with the right
amount of baby chubbiness, he wasn't, he was very thin, he didn't just look
small, he looked wrong.

Somehow I slipped through the net, the 32 week scan was so reassuring that
any concerns were forgotten, then when I arrived at hospital to be induced
(or augmented, I was contracting, but not strongly enough to dilate) due to
ROM, the doctor had one feel and said I want that baby out today.

An interesting but maybe irrelevant fact is that throughout that pregnancy I
struggled with low blood pressure (100/50 or lower) whereas during my 2nd
pregnancy my blood pressure was right within normal range.

Cheers

Anne

wrote:
Based on these two
measurements alone, they estimated his weight at only 5 lbs. 1 oz.,
which is small for his gestational age. This was surprising to me since
the baby's father and I are both tall, and because at a previous
ultrasound (28 weeks), he was measuring a full week ahead in size

Okay, you have two reasons for surprise about the baby's estimated
current size.

Reason 1:
the baby's father and I are both tall

Not relevant. What matters is how large *at birth* were you, the
baby's
father, and all your respective siblings. If the majority were healthy
but
small, you have nothing to worry about on this count.

Reason 2:
at a previous
ultrasound (28 weeks), he was measuring a full week ahead in size

Now this difference is a concern. Could one or the other result be
wrong? Did the same technician do both scans? How many times
did he/she repeat each measurement during the scan?


and
his weight was estimated at 3 lbs.

My doctor was concerned at the apparent lack of growth as determined by
the 36 week ultrasound, so I was given the diagnosis "probable IUGR"
and ordered to go to the hospital twice a week for non-stress tests and
ultrasounds to check my amniotic fluid level. So far, all of these
tests have come back great.

Nonetheless, my doctor seems reluctant to offer me any reassurance that
my baby might actually be okay. When I questioned the accuracy of the
ultrasound, he became offended and asked if I'd prefer no care at all.
When I reminded him that my fundal height measurements have always been
perfect, he explained that because fundal height is only most accurate
between weeks 28-32 and included the amniotic fluid and placenta, it's
really no indication that my baby could be growing normally. He
basically makes me feel as if having a healthy baby is a long shot, and
I shouldn't be at all hopeful for a good outcome. His attitude has
really turned me off to doctors in general, especially the medical
treatment of pregnancy. If I could switch caregivers this late in my
pregnancy without also having to change hospitals, I would do so in a
heartbeat.

So, I'm seeking opinions on how concerned I should be about the health
of my baby. Has anyone been through a similar experience? Any and all
opinions/advice/information would be most appreciated!

Thank you.

alath wrote:

Using the fetal growth nomogram published by Alexander et al (1998),
the 10th percentile of weight for a 38 week fetus is 2714 grams and the
5th percentile is 2543 grams. Different studies have used different
definitions of small for gestational age (SGA) but 5th percentile and
10th percentile are the usual definitions. Using 10%tile as a cutoff,
your baby is SGA even at the upper limit of likely weight estimate
error. Even using the stricter 5%tile cutoff, your baby's estimated
weight of 2296 grams is less than the cutoff. So the diagnosis of SGA
is very likely correct. It could be wrong, but that's not likely.

But wait, wait, wait -- she's 38 weeks NOW, but the ultrasound was at
36 weeks, wasn't it? Doesn't that change the values? I thought 5.5
pounds was fairly normal for a 37-week baby, so why would 5.1 be so low
for a 36-week one? Or am I misinterpreting or misremembering the first
post?

--Helen

wrote:
alath wrote:

Using the fetal growth nomogram published by Alexander et al (1998),
the 10th percentile of weight for a 38 week fetus is 2714 grams and the
5th percentile is 2543 grams. Different studies have used different
definitions of small for gestational age (SGA) but 5th percentile and
10th percentile are the usual definitions. Using 10%tile as a cutoff,
your baby is SGA even at the upper limit of likely weight estimate
error. Even using the stricter 5%tile cutoff, your baby's estimated
weight of 2296 grams is less than the cutoff. So the diagnosis of SGA
is very likely correct. It could be wrong, but that's not likely.


But wait, wait, wait -- she's 38 weeks NOW, but the ultrasound was at
36 weeks, wasn't it? Doesn't that change the values? I thought 5.5
pounds was fairly normal for a 37-week baby, so why would 5.1 be so low
for a 36-week one? Or am I misinterpreting or misremembering the first
post?

Ahhhh, I believe you are correct. The u/s was at
36 weeks. On the fetal growth chart I found, that put it
at around the 10th percentile. So, still small, but the
upside of the error range would be outside the definition
for SGA, and the downside of a +/- 15 percent error range
would be about 3rd percentile. Still worth keeping an
eye on, but even more hopeful.

Best wishes,
Ericka

Helen saves the day ;-)
Yes, you are right - I misread the original post.
That moves half of the error distribution above the 10th percentile,
which improves the outlook considerably.