My wife and I are expecting our first baby in October.  We recently
recieved our MSS/Triple Screen tests back and found out that our
likelyhood of having a baby with downs syndrom increased from 1:895
(based on my wifes age) to 1:117 (based on the MSS test results).  My
question is this, I have the AFP, uE3, hCG test result figures and the
Mom's in which they used... is there a calculator that I can use to
figure out where they came up with this 1:117 rating.  The problem is
that apparently Last Menstral Period (LMP) has allot to do with the
results and we recently discovered the we were off on the LMP date.  I
want to plug in the correct numbers into the calulator to find the new
result.

Hi travel_travel_travel and thanks for the question.

Infact the calculation is a complex one and is done by computer,
however I was able to find a description of the calculations  which
should be of help to you.  This is what the website I found says about
the calculation “A complex mathematics which involves trivariate
Gaussian distribution analysis are required for the calculation of the
risk.”
I would suggest you contact your health care specialist as soon as
possible and tell them that you think some of the information you gave
might be incorrect, and ask for a second test (if time allows).

The description for the calculations is available in this PDF document
from the “Department of Pathology and Laboratory Medicine Allegheny
University of the Health Sciences”
http://www.cacb.org.tw/journal/981001/981001_1.pdf

A company called Benetech  has developed software called “AFP Expert”
which does the analysis
http://www.benetech.com/afpx.htm


On a more personal note, I can understand your concerns very well as
my wife gave birth to our first child at the age of 36 last year (and
she is slightly overweight) and so her score indicated a more likely
chance of our baby having Downs Syndrome, fortunately everything was
fine and our son is now a very happy one year old.


Good luck to you and your wife, and I urge you again to contact your
health care provider and tell them of the situation.

THX1138

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Request for Answer Clarification by travel_travel_travel-ga on 16 Jun 2002 20:47 PDT

Thank you for your note.  What i'm looking for is an online version of
the software in which Benetech sells.  The printout I received from
our doctor is exactly what is found at
http://www.benetech.com/a-report.htm.  I'm looking for an online
verison that can be easily used and get immdiate answers.

---

Clarification of Answer by thx1138-ga on 16 Jun 2002 21:26 PDT

Hi travel_travel_travel 

Unfortunately it seems there is no online calculator available, which
is why it takes so long for you to get the results from your doctor,
and your anxiety in waiting for the results is completely
understandable (I have been through it too)
As missy mentioned in her excellent follow up, an ultrasound scan
would be able to confirm fetal age if you are still in doubt about the
LMP date.
I’m sorry that you’re anxiety is not going to be releaved today, but
remember that the test only gives a statistical likelihood and cannot
tell you if your baby will or will not have problems.

I hope some of the information I found I was of use to you.

Good Luck 

THX1138   

Some of the search strategies I used were:
"Triple Screen test " calculator
://www.google.com/search?hl=en&lr=&as_qdr=all&q=+%22Triple+Screen+test+%22+calculator&btnG=Google+Search

"alpha-fetoprotein test"
://www.google.com/search?hl=en&lr=&as_qdr=all&q=+%22alpha-fetoprotein+test%22+&spell=1

"alpha-fetoprotein test" "are calculated"
://www.google.com/search?q=+%22alpha-fetoprotein+test%22+%22are+calculated%22&btnG=Google+Search&hl=en&lr=&as_qdr=all

"alpha-fetoprotein test" online
://www.google.com/search?hl=en&lr=&as_qdr=all&q=+%22alpha-fetoprotein+test%22+online&btnG=Google+Search

Hi there.

I wasn't able to locate such a calculator, but perhaps I can help ease
your mind a little.

If the LMP date submitted was incorrect, it would indeed throw results
off. According to the London (Ontario) Health Sciences Center:

"The optimum gestation age for specimen collection is at 16 weeks of
gestation age. Risk calculations can not be done on gestation ages
less than 15 weeks, 0 days or more than 20 weeks, 6 days."

Maternal Serum Screen
http://www.lhsc.on.ca/lab/endo/endmss.htm

That's a pretty narrow window for accuracy, and the vagaries of the
menstual cycle don't help that at all:

"Between 25 and 45% of women are unable to provide an accurate
menstrual history."

A Guidline for Ultrasound As Part of Routine Prenatal Care
http://www.albertadoctors.org/resources/cpg/prenatal-guideline.pdf

I'm a two time mom (two boys, 10 and 6), and I remember with horror
the MSS/Triple screen, and all the anxiety they caused.  With both
pregnancies, I had elevated levels of AFP in the first trimester. 
Both times, the test was repeated. With the eldest, the second test
came back normal.

With the youngest, it didn't.  My OB and I discussed my options, and
we decided upon amniocentisis to check for trisomy-21.  I was a basket
case until the day I went in to hear test results and saw an actual
picture of my son's chromosomes all lined up in 23 perfect pairs.  My
OB, bless him, was very careful to point out all along that the MSS
tests are sometimes wrong.  (Believe me, I had nothing but dreadfully
unprintable things to say about a test that would make an already
worried soon-to-be mother more worried than she already was.)

Perhaps the following articles discussing the MSS in general and the
AFP test specifically will help to calm your nerves:

Prenatal Screening for Down Syndrome
http://www.ds-health.com/prenatal.htm

Alpha-Fetoprotein Test (AFP)
http://www.babycentre.com/refcap/1487.html

Consider asking your practitioner for an ultrasound to confirm fetal
age.  If Peanut is a bit older than originally thought, you may be
able to breathe just a little bit easier - advanced fetal age is one
of the main causes of a false positive.  If you're *still* worried
after that, consider amniocentisis to stomp out all doubt.  I'll be
forthright - it's terribly uncomfortable, but the peace of mind an
A-OK test gives is well worth the 20 minutes of dull ache.

I hope this helps settle your nerves just a little.  Even though I've
not posted an answer, I'd still be happy to help you find more
information.  One parent to another. Don't hesitate to ask.

Congratulations on the impending new arrival, and Happy Father's Day. 
You're going to have a great time - I've been at it for 10 years, and
the kids still surprise me every day.

Best of luck,

missy-ga

As a side note, I would recommend that your wife read Toni Weschler's
book "Taking Charge of Your Fertility".  You can see more information
on this book on her web page:
http://www.tcoyf.com/products/bookstore.asp

One of the biggest misconceptions in female fertility is that women
ovulate 14 days after the start of the menstrual cycle.  This is
simply not true.  Women can ovulate at any time of the cycle, either
day five, or day forty-five.  This is important to know because it
will tell you the *actual day that you conceived*, and thus, the
actual age of the fetus.  This is important becasue then you know your
*real* due date, not a due date based on the day-14-myth.  (The book
explains how to tell when you ovulate by taking daily basal
temperatures and checking cervical fluid.)

Anyway, I realize that it is too late for your wife to read this book
to know when she ovulated in this pregnancy.  BUT, I promise her that
she will find it is an interesting read, whether or not you two are
planning on having more children.

I'm not affiliated with Toni Waschler, but I am a big fan.  I only
regret that I didn't read her book years ago.

By the way, congratulations on your pending fatherhood, and I wish you
both a safe and healthy baby.

Regards,

Truswell