Re: Anomaly scan, Serum testing, Down Syndrome and Lateralventricles
From: jworrall@alaska.net
Thu Jul 10 12:49:22 2008
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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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