Re: mid-term femur length trisomy risk query
From: M Willmann (fizztastic@talk21.com)
Thu Nov 17 06:34:09 2005
James,
Your comments have been very illuminating. I am
deeply indebted to you for your detailed and careful
reply. Thanks very much.
Warm regards,
Mary
--- James Smeltzer <James.Smeltzer@wellstar.org>
wrote:
> Hi!
>
> Bernacerraf's group has studied this extensively.
> The use of isolated
> single measures to positively predict Down's
> Syndrome sonographically is
> not reliable, except the positive predictive value
> of atrioventricular
> septal defect (Downs vs field 2:1), duodenal atresia
> or web (1:2). The
> physiognomy, body type, arms, legs, hands, feet of a
> fetus should always
> be referenced to parents if possible, but very short
> is high risk, even
> with short parents IMHO.
>
> The problem is that a 40 y/o woman has a prior risk
> of 1/50, change to
> about 1/200 by nuchal lucency.
>
> Please check and comment on:
> nose bone (missing or small very common, upturned
> common),
> head shape (brachycephalic very common),
> ear length (short, low, simple very common),
> facial appearance especially mid-face projection
> (flat extremely
> common) and
> overall shape (round very common),
> current nuchal thickness (thickened common),
> humerus length (short very common),
> digits hand: (simian crease reported, but I have
> never seen it)
> (phalanges graduated stacked box appearance very
> common), especially 5th
> finger (clinodactyly with small and wedged MP of 5
> is very common) and
> 1st toe (wide space very common), (short, wide feet
> very common),
> four-chamber heart, especially atrial dimensions of
> right vs left
> (right predominance in 85% by DeVore very common)
> and crux (straight
> across or missing in AV canal 5% but highly
> predictive), other heart
> defects effusions or hydrops (common - 50%, but less
> prenatally),
> umbilical artery (single uncommon but predictive),
> stomach appearance (double bubbles uncommon but
> predictive: one-third
> have DS),
> kidney appearance (renal pelvis dilation, mild
> common),
> bowel appearance (bright occasional but predictive),
>
> pelvis width (wide max outer to outer ilial diameter
> vs femur length
> common) and angle (>45 degrees, not reproducible by
> some common).
>
> We are starting on the wrong end of this equation,
> IMHO. People not
> only come in all shapes and sizes, they also have
> all kinds of
> dispositions.
> Do they wish prenatal diagnosis? If not, you are
> done unless there is
> a gross heart or other defect or hydrops.
> Is targeted imaging and expert counselling
> available? If so, they need
> it.
> Do they wish certainty regarding chromosomes? Is she
> losing sleep over
> this? Would she have an abortion? If so, needs
> amniocentesis.
>
> I will never forget the 35 year-old woman I cared
> for years ago in St.
> Louis. Missouri medicaid would not pay for prenatal
> genetic diagnosis.
> My chief, the late honorable Klaus Staisch, believed
> that providing this
> service was standard of care even in an indigent
> care hospital. The
> hospital ate the $700 a pop that Jim Crane charged
> us for the
> chromosomal evaluations - no discounts. You better
> believe we provided
> structured counselling. This woman desired amnio
> despite a negative
> sonogram. The results returned trisomy 21. I
> rescanned her with the
> results in hand, and the sonogram was normal. She
> carried the
> pregnancy. When the baby was born, I asked Corinne
> Valentik, our
> neonatologist, if the baby had a heart defect I had
> missed. SHe asked
> "What baby?" I said the one with Down's. She said
> that there was no
> baby in the nursery with Down's. I pointed the baby
> out to her and she
> said the baby did not have Down Syndrome: there was
> no sign of Down
> Syndrome. I said I had known that for five months,
> but it did not
> change the chromosomes. She was so skeptical she
> repeated them in a
> different lab. The results were the same, Trisomy
> 21.
>
> That baby taught me that dysmorphology only goes so
> far. The number
> and appearance of chromosomes is a fact. When you
> are only interested
> in that fact, the chromosomes are the things you
> should look at. When
> we can consistently and accurately harvest fetal
> cells at reasonable
> cost from maternal blood I will be out of that
> business. Until then, I
> enjoy the prenatal diagnosis and am happy that so
> far this is the only
> miss so far, and that my positive amnio rate for
> chromosomal
> abnormalities is between 20 and 35 percent. But I
> will never have a
> problem doing an amnio when the patient wants this
> certainty.
>
> "When all you have is a hammer, everything looks
> like a nail" ...
> (anonymous)
> ;^)
> 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
>
> >>> fizztastic@talk21.com 11/15/2005 2:33:46 PM >>>
> The patient is 40 years old; her partner is 50.
> This is their first
> pregnancy. They are very concerned about
> age-related risk of
> chromosomal abnormalities, but opted against CVS and
> then amnio when
> 1st
> trimester screening adjusted their background
> trisomy 21 risk to 1:272
> and trisomy 13/18 risk to 1:843.
>
> The mother is above average height (183 cm) and the
> father is below
> average height (168 cm). Both are Causasian. My
> question is this: at
> 21 weeks + 3 (dated by known LMP), the femur length
> of the fetus is
> 33.5
> mm. (Other measurements taken at the same time
> include BPD 53 mm; HC
> 182 mm; TCD 21 mm; CM 5 mm and AC 161 mm.) Is this
> low enough to
> warrant
> concern? Urgently seeking advice. Any comments
> would be gratefully
> received. Thanks very much.
>
> Mary
>
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