Re: Anomaly scan, Serum testing, Down Syndrome
From: James Smeltzer (James.Smeltzer@wellstar.org)
Wed Jul 16 11:28:39 2008
Hi!
The neural tube does stay roughly the same diameter, the cells of the
wall multiply and migrate to their designated location.
See: http://en.wikipedia.org/wiki/Neural_development
We use cut-off of same measurements but 14w 3 days as we use the same
BPD measures.
The "normal" pregnancy is 280 days from last menses onset. This is also
about ten moons from the last menses. I suggest that we use decimal
moons () to mark time, since this leads to a clear and unambiguous use
of the decimal system. One pregnancy is overdue if it is ten moons. One
lunar period (orbit of the earth) is 27.3 days. Ten is 273 days, or a
little short of the normal gestational period measured in many cultures
and ethnic groups as 278 to 280 days, so the correlation is not perfect.
On the other hand, we could use the synodic period (apparent mood
period, because it is going around the earth in the same direction as
the earth goes around the sun, one lunar cycle is missed from each earth
cycle, just as a "day" is 1/365.4 short of a complete rotation of the
earth) variations in the geometry of the Earth–Moon–Sun system are
responsible for the lunar phases that repeat every 29.5 days (the
synodic period). A normal pregnancy is 9.5 of these. A week is 7/29.5 .2373 "moons". A day is .033898305 "moons". An hour is .00141 moons, and
a minute is... - on the other hand this does not seem to be an
improvement over decimal weeks. We just need to remember that a day is
.142857142... decimal weeks, and we need to remember that every morning
we are .142857142 weeks older. Every day at the top of our antepartum
notes we need to add .142857142 to our estimated gestational age... --
on the other hand let's stick to days. I cannot do that kind of math in
my head any more, so I like adding one every day, which I can still do
in my head.
;^} JSS
>>> <jworrall@alaska.net> 7/14/2008 2:58 PM >>>
I believe the Fetal Medicine Foundation still advocates 11 weeks to 13
weeks
6 days, or CRL 45 to 84 mm. I have always wondered whose table of CRL
they
use, because in Hadlock's table, 84 mm is 14.3 weeks.
Yes, I shall post some images if I can obtain the measurement of the
atria
of the lateral cerebral ventricle during the Nuchal Translucency scan.
Allen
>----- Original Message -----
From: "DuBose, Terry" <DuboseTerryJ@uams.edu>
To: "Multiple recipients of list ULTRASOUND"
<ultrasound@mail.obgyn.net>
Sent: Monday, July 14, 2008 10:21 AM
Subject: Re: Anomaly scan, Serum testing, Down Syndrome
andLateralventricles
> Allen. That will be great. Especially at the end of the 13th week.
> Can
> you post an image or two?
>
> Has Nicolaides, et al changed the date of the scan from 11-14 weeks?
>
> Thanks, Terry
>
> Terry J. DuBose, M.S., RDMS, FSDMS, FAIUM
>
> Associate Professor & Director
> Diagnostic Medical Sonography Program
> University of Arkansas for Medical Sciences, CHRP
> 4301 West Markham St. Mail Slot #563
> Little Rock, Arkansas, 72205 USA
> 501-686-6510 or 501-686-5948
> DuBoseTerryJ@UAMS.edu
> http://www.uams.edu/chrp/sonography/
> http://www.obgyn.net/us/panel/panel.htm
> http://www.io.com/~dubose/
> ---------------------------------------------------------------
> P Please consider the environment before printing this e-mail
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> -----Original Message-----
> From: ultrasound@obgyn.net [mailto:ultrasound@obgyn.net] On Behalf
Of
> jworrall@alaska.net
> Sent: Monday, July 14, 2008 1:00 PM
> To: Multiple recipients of list ULTRASOUND
> Subject: Re: Anomaly scan, Serum testing, Down Syndrome
> andLateralventricles
>
> I shall try to measure the atrium of the lateral cerebral ventricle
at
> 12-13
> weeks, when I am doing a nuchal translucency and first trimester
> evaluation.
> I have only measured the atria in the second trimester.
>
> Allen
>> ----- Original Message -----
> From: "DuBose, Terry" <DuboseTerryJ@uams.edu>
> To: "Multiple recipients of list ULTRASOUND"
<ultr
asound@mail.obgyn.net>
> Sent: Monday, July 14, 2008 8:50 AM
> Subject: RE: Anomaly scan, Serum testing, Down Syndrome
> andLateralventricles
>
>> Well... depends on the author. Callen's new textbook (5th edition)
>> shows
>> the BPD to be from 20 to 23 mm during the 13th week (13.2-13.8
weeks).
>> My
>> own measurements show the BPD to be 23 mm at 13 weeks, based upon
several
>> thousands of cases. We really don't have any precise measurements,
and
>> many
>> refer to any fetus between 13.0 and 13.9 weeks, "as 13 weeks".
This is
>> the
>> reason I have always advocated estimating fetal age to the 1/10 of a
>> week,
>> rather than just weeks or even weeks + days... it is easier to
average
>> the
>> multiple fetal parameter ages after Hadlock's method.
>>
>> This really does not tell us the precise measurement, "I have a 33yr
old
>> gravida2, with 13 weeks pregnancy, scan done today shows mild
>> ventriculomegaly...."
>>
>> It may be that because at 13 weeks the choroid plexus and lateral
>> ventricles
>> appear to fill the cerebral hemispheres that the "mild
ventriculomegaly"
>> call
>> was made. Without measurements we can't argue the point.
>>
>> But I do believe that by the start of the 1st trimester, the
lateral
>> ventricular atria has reached 7-10 mm and remains that size as the
head
>> and
>> cerebrum enlarges around them.
>>
>> Terry J. DuBose, M.S., RDMS, FSDMS, FAIUM
>>
>> Associate Professor & Director
>> Diagnostic Medical Sonography Program
>> University of Arkansas for Medical Sciences, CHRP
>> 4301 West Markham St. Mail Slot #563
>> Little Rock, Arkansas, 72205 USA
>> 501-686-6510 or 501-686-5948
>> DuBoseTerryJ@UAMS.edu
>> http://www.uams.edu/chrp/sonography/
>> http://www.obgyn.net/us/panel/panel.htm
>> http://www.io.com/~dubose/
>> ---------------------------------------------------------------
>> P Please consider the environment before printing this e-mail
>> ---------------------------------------------------------------
>>
>> ---------------------------------------------------------------
>>
>> -----Original Message-----
>> From: ultrasound@obgyn.net [mailto:ultrasound@obgyn.net] On Behalf
Of
>> James
>> Smeltzer
>> Sent: Friday, July 11, 2008 5:44 PM
>> To: Multiple recipients of list ULTRASOUND
>> Subject: RE: Anomaly scan, Serum testing, Down Syndrome
>> andLateralventricles
>>
>> Just a comment that the normal 13 week BPD is 20. Even though the
LVs are
>> close to 10, as every cell in the brain must come from the wall of
the
>> tube,
>> and few cells have been made yet, the whole cannot be greater (or
less)
>> than
>> the sum of its parts.
>> JSS
>>
>>>>> "DuBose, Terry" <DuboseTerryJ@uams.edu> 7/11/2008 6:06 PM >>>
>> Not necessarily for 10 mm... 15 mm is too large at any age.
However, at
>> 13
>> weeks the ventricles fill most of the cranium and appear to be huge
>> compared
>> to the rest of the head. The choroid appears to fill the
hemispheres of
>> the
>> cranium at 13 weeks.
>>
>> I can't find a specific image with measurements at 13 weeks, but in
Fetal
>> Sonography, p. 431 there is a sonogram that shows the choroid plexus
and
>> lateral ventricles to be at 10 mm in width (the scale is on the
image).
>> Also, I found an image of a 13 week fetal head in Callen's latest
edition
>> (5th edition, p. 364) that show the structures and describe them as
",
>> the
>> intercrainal anatomy is dominated by the prominent choroid plexuses
of
>> the
>> lateral ventricles."
>>
>> I don't know when the width of the lateral ventricles actually
reaches
>> 7-10
>> mm, but it is during the end of the 1st trimester. The head then
grows
>> larger around the ventricles, which make them appear to become
smaller,
>> but
>> they remain about <10mm in width throughout the rest of the
gestation.
>>
>> Terry J. DuBose, M.S., RDMS, FSDMS, FAIUM
>>
>> Associate Professor & Director
>> Diagnostic Medical Sonography Program
>> University of Arkansas for Medical Sciences, CHRP
>> 4301 West Markham St. Mail Slot #563
>> Little Rock, Arkansas, 72205 USA
>> 501-686-6510 or 501-686-5948
>> DuBose
TerryJ@UAMS.edu
>> http://www.uams.edu/chrp/sonography/
>> http://www.obgyn.net/us/panel/panel.htm
>> http://www.io.com/~dubose/
>> ---------------------------------------------------------------
>> P Please consider the environment before printing this e-mail
>> ---------------------------------------------------------------
>>
>> ---------------------------------------------------------------
>>
>> -----Original Message-----
>> From: ultrasound@obgyn.net [mailto:ultrasound@obgyn.net] On Behalf
Of
>> jworrall@alaska.net
>> Sent: Thursday, July 10, 2008 12:52 PM
>> To: Multiple recipients of list ULTRASOUND
>> Subject: Re: Anomaly scan, Serum testing, Down Syndrome and
>> Lateralventricles
>>
>> Thanks Dr. Smeltzer. Yes, I realize now that an atrium of 10-15 mm
at 13
>> weeks would mean the fetal head had to be enormous.
>>
>> Allen
>>> ----- Original Message -----
>> From: "James Smeltzer" <James.Smeltzer@wellstar.org>
>> To: "Multiple recipients of list ULTRASOUND"
<ultrasound@mail.obgyn.net>
>> Sent: Thursday, July 10, 2008 1:44 AM
>> Subject: Anomaly scan, Serum testing, Down Syndrome and
Lateralventricles
>>
>>> Hi!
>>>
>>> All the cells of the CNS are lining cells of the wall of the tube
that
>>> started there, migrated out to their final position and did what
they
>>> were
>>> supposed to do, based on where they came from and other factors.
>>>
>>>>From a CNS perspective we are all totally tubular!
>>>
>>> It only stands to reason that the starting mass of cells outside
the
>>> tube
>>> is small, and grows as more join them.
>>>
>>> This is the way of the tube.
>>>
>>> Allen, 10-15mm seems a bit generous for the LV tube diameter at
the
>>> atrium
>>> at 13 weeks, since as the BPD is only 20mm and has to include one
side
>>> of
>>> the skull and the entire brain, and the two LVs are at a slightly
>>> higher - and narrower - level of the brain (but still have SOME
brain
>>> substance at 13 weeks.
>>>
>>> A nuchal translucency of 2.6mm at 13 weeks (~CRL 67) is sufficient
to
>>> discuss/offer an amnio or CVS and fetal echo, or serum testing,
>>> tqargeted
>>> sonogram (our preferred route), as the odds ratio for Down Synd is
about
>>> .75/.05. or about 15 fold the baseline age and other screening
risk
>>> (Snijders & al, Lancet 1998; 351:343-6). Yagel & al Ult. (Obstet.
>>> Gynecol
>>> 11:262, 1998) come up with more conservative numbers, and if your
normal
>>> data fit their curve, you are right not to routinely offer an amnio
to a
>>> womal under 31, as their predicted nuchal lucency is 2.6 mm. (Odds
ratio
>>> of ~2 - not sure of their Down results).
>>>
>>> I am not recommending everyone rely as heavily on dysmorphology as
we
>>> do,
>>> as there is a learning curve, amnio is 100% (99.4%) reliable and we
do a
>>> ridiculously low number of amnios - with a ridiculously high
positive
>>> rate. But looking never killed a baby.
>>>
>>> I would definitely look for tricuspid regurgitation, brachycephaly
-
>>> which
>>> can be seen early - short femur, and humerus, and an absent nose
bone,
>>> at
>>> least. Of course an AV septal defect alone would be sufficient to
>>> warrant
>>> an amniocentesis. Personally, in our hands, serum markers have
helped to
>>> identify Down syndrome only once in the absence of a suggestive
>>> sonogram,
>>> but have - with quad screen - gotten to an acceptably low false
positive
>>> rate, low enough to raise the odds, and significantly increase the
>>> detection of Down syndrome in the absence of early careful
sonography.
>>>
>>> Know your results and your normal curve for NL as these are
essential
>>> for
>>> interpretation of results. (I still do not understand how we get
such
>>> different normals. Maybe we should all take the same course;^)
>>>
>>> Hope this helps! Jim Smeltzer
>>>
>>> James S. Smeltzer, MD, FACOG, SMFM
>>> Consultant, Maternal Fetal Medicine
>>> Wellstar Physicians' Group
>>> Northwest Women's Care
>>> 787 Campbell Hill St
>>> Marietta GA 30060
>>> James.Smeltzer@wellstar.org
>>> VM 678-290-3035
>>> Off 770-528-0260
>>> Page 404-318-3451
>>>
>>>>
>> Terry DuBose <terrydubose@sbcglobal.net> 7/5/2008 2:14 PM >>>
>>> I think Allen is correct, the ventricles often appear large early
on,
>>> but
>>> as the head grows up around them, they tend to look more normal...
need
>>> measurements later. Terry
>>>
>>> jworrall@alaska.net wrote: At 13 weeks a transvaginal scan will
often
>>> (but not always) permit a very
>>> good view of the fetal head. I am not sure what "mild"
ventriculomegaly
>>> is,
>>> but probably the atrium of the lateral cerebral ventricle measures
>>> between
>>> 10 and 15 mm. If a good view of the fetal head can be obtained, you
>>> would
>>> be
>>> able to evaluate the posterior cerebral fossa, and look at the
posterior
>>> end
>>> of the occipital horn (is it rounded or pointed?) the cisterna
magna,
>>> and
>>> the cerebellum. Remember that this early in pregnancy the
cerebellar
>>> vermis
>>> is not completely formed, so as you scan the posterior cerebral
fossa
>>> inferiorly, you may mistakenly think you have a Dandy Walker
situation.
>>> I
>>> am not sure you would see the cavum septi pellucidi that early.
>>>
>>> Hopefully, in addition to the nuchal translucency, the patient has
been
>>> able
>>> to obtain the blood test part of that genetic screen, the PAPP-A
and
>>> beta
>>> hcg, so that you will get a proper evaluation of her risk of having
a
>>> baby
>>> with Trisomy 21. I do NOT think mild ventriculomegaly and a nuchal
>>> translucency of 2.6 mm would be an indication for amniocentesis or
>>> chorionic
>>> villus sampling but I guess that depends on where you practice and
what
>>> the
>>> custom is in your location. As always, I hope Anita and Prathima
will
>>> comment.
>>>
>>> Allen
>>>
>>> --------------------------------------------------
>>> From: "cjayankar" Sent: Saturday, July 05, 2008 3:16 AMTo:
>>> --------------------------------------------------
"Multiple
>>> --------------------------------------------------
>>> recipients of list ULTRASOUND"
>>> Subject: anomaly scan
>>>
>>>> hello
>>>>
>>>> I have a 33yr old gravida2,with 13 weeks pregnancy,sacn done
today
>>>> shows mild ventriculomegaly and NT 2.6mm.Her first child is 7yrs
old
>>>> and
>>>> autistic.No significant family or past history.
>>>>
>>>> Planning for anomaly sceening,can the mild ventriculomegaly be
taken
>>>> as very significant.
>>>>
>>>> Thank You
>>>> jayankar
>>
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