Re: 'Terrifying Sonogram' Dilemma: patient with single (new) 'soft marker' -- UPDATE
From: RBurns (bito02@aol.com)
Fri May 30 13:38:20 2003
Just FYI --
Patient had a Level II u/s with Dr. Roy Filly yesterday and he located
the nasal bone. It WAS a matter of getting the right scan. A perfect
example regarding the contradictions and issues raised in his article.
-- RBurns
At Tue, 27 May 2003, Dave Berck wrote:
>
>Thank you Dr. Nyberg. As concerns the nasal bone, if
>the LR is as high as 40, wouldn't virtually any
>patient with this finding, even those who may have
>screened negative by 1st or 2nd trimester screening,
>into the category of "screen positive," i.e. a T-21
>risk above the traditional age-related risk of a 35
>year old (about 1:270)? (I guess that's what I mean by
>a "hard marker", although I appreciated the
>distinction you have drawn between markers which are
>themselves significant anomalies and those that are
>not).
>
>--- David Nyberg <nyberg@u.washington.edu> wrote:
>> The nasal bone is a "soft" marker and fulfills some
>> of the same criteria as other markers
>>
>> - it is not inherently significant itself, ie it
>> carries not morbidity or mortality. It cannot be
>> equated with a cardiac defect or omphalocele.
>> - the marker (hypoplastic nasal bone) may be
>> observed in normal fetuses but is more likely in
>> aneuploid fetuses. It carries an inherent likelihood
>> ratio.
>>
>> The question is, what is the likelihood ratio
>> (risk)? As with other markers, there are other
>> variables to consider. The likelihood ratio is
>> considerably lower in African-Caribbean populations
>> because of the higher false positive rate.
>> Gestational age is undoubtedly a factor since the
>> nasal bone is more likely not to be visible early
>> (10-12 weeks) than later (13-14 weeks). The
>> orientation of the fetus and the angle of the scan
>> make a big difference. Factors of ethnicity,
>> gestational age, and orientation of the fetus also
>> affect the marker of echogenic intracardiac foci.
>> The only real difference is the likelhood ratio is
>> much less for EIF and may not be significant once we
>> account for all other factors, including the nasal
>> bone during the second trimester. In the first
>> trimester, current estimates of LR for absent nasal
>> bone may range as much as 10-40 depending on some of
>> these factors. It may be high, but it is still a
>> nonspecific marker.
>>
>> On Fri, 23 May 2003, Dave Berck wrote:
>>
>> > Nicolaides Lancet paper about 18 months ago
>> describes
>> > the proper way to image the nasal bone in the 2nd
>> > trimester. Like NT measurements, if you don't know
>> > what you're doing, you'll definitely do a bad job.
>> I
>> > would suggest that there are few radiologists who
>> have
>> > any idea of how to measure a NB properly.
>> >
>> > Furthermore, the finding of a soft marker should
>> not
>> > cause you to throw the screening results out of
>> the
>> > window. You have to consider them in aggregate.
>> >
>> > Lastly, I would suggest that the finding of an
>> absent
>> > nasal bone is actually NOT a soft marker, but
>> rather a
>> > marker that greatly increases the risk of DS, more
>> > along the lines of an AV Canal defect or
>> omphalocele.
>> >
>> > Does anyone agree?
>> >
>> > --- RBurns <bito02@aol.com> wrote:
>> > > This "may" communication is my error, not an
>> error
>> > > in the report. The
>> > > actual report indicates that "they are concerned
>> > > about the development
>> > > of the nasal bone." In the original Level II
>> u/s,
>> > > the nasal bone appears
>> > > present; in the subsequent Level I, it is
>> absent.
>> > > Thus, they are
>> > > suggesting that there is something concerning
>> about
>> > > the development of
>> > > the nasal bone itself.
>> > >
>> > > But I surely agree; Levels are only as good as
>> the
>> > > sonographers
>> > > performing the screen --
>> > >
>> > > Does that clarify things?
>> > >
>> >
>> > =====
>> > David J. Berck, MD, MPH
>> >
>>
>> David Nyberg, MD
>> 10401 E McDowell Mtn Ranch Rd
>> #2-372
>> Scottsdale, AZ 85255
>> ph 480-797-0993
>> fax 480-513-7765
>> work 480-425-5000
>>
>=====
>David J. Berck, MD, MPH
