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Scan report showed thick neck measurement giving 1 in 17 risk of having a down syndrome. What to do?

May 2014
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Practicing since : 2002
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My daughter in law was advised that her baby's 13th week sonogram showed a thick neck measurement giving her a 1 in 17 risk of having a down syndrome baby. They have an appointment Wednesday with a specialist. They can't do an amnio for 2 weeks because of how far along she is. Would she be out of line asking for another sonogram for more measurements of things like the bridge of the nose and femur and any other markers just to give her more information before the amnio? What other questions would be good to ask this specialist?
Posted Sat, 19 Oct 2013 in Women's Health
Answered by Dr. Vivek Chail 1 hour later
Brief Answer:
Many markers on sonogram to be discussed.

Detailed Answer:
Thanks for writing in to us.

I have read through your query in detail.

Answering your specific query first, the potential markers on sonogram include:
1. absent or small nose bone
2. dilated brain ventricles
3. mild kidney swelling
4. bright spots in the heart
5. 'bright' bowels
6. shortening of an arm bone or thigh bone (femur)
7. an abnormal artery to the upper extremities
8. increased thickness of the back of the neck

Sonogram may be done but it is not an absolute marker for Down's. You may discuss above points with your doctor as seen on sonogram.

Risk calculation in possible Downs

As you might be aware, nuchal (neck) translucency (NT) is one of the markers for a possible Downs's syndrome baby. This is however not the only marker. You have not mentioned any other tests therefore I would like to clarify regarding how the risk of 1:17 was calculated? Were other test results included while calculating the risk?

Some of the components which can give better insight to risk of Down's syndrome risk calculation are:
1. Free beta HCG levels
2. Pregnancy Associated Plasma Protein-A (PAPP-A) levels
3. Maternal age
4. Nuchal translucency
5. Crown rump length CRL

If the risk remains very high then doing a triple screen test might help to further estimate the risk.

Please find details about triple test given below.

The triple screen test is a maternal blood screening test that looks for three specific substances: AFP, hCG, and Estriol.

AFP: alpha-fetoprotein is a protein that is produced by the fetus.
hCG: human chorionic gonadotropin is a hormone produced within the placenta
Estriol: estriol is an estrogen produced by both the fetus and the placenta
It is a non-invasive procedure done through a blood test with little to no known risk to the mother or developing baby.

What does the triple screen test look for?
The triple screen is measuring high and low levels of AFP and abnormal levels of hCG and estriol. The results are combined with the mother’s age, weight, ethnicity and gestation of pregnancy in order to assess probabilities of potential genetic disorders.

High levels of AFP may suggest that the developing baby has a neural tube defect such as spina bifida or anencephaly. However, the most common reason for elevated AFP levels is inaccurate dating of the pregnancy.

Low levels of AFP and abnormal levels of hCG and estriol may indicate that the developing baby has Trisomy 21(Down syndrome), Trisomy 18 (Edwards Syndrome) or another type of chromosome abnormality.

The triple test might also be done just before aminocentesis if felt necessary by your doctor.

Aminocentesis gives an accurate result in detecting Down's and it is surely necessary to be done for your daughter in law around 15 weeks into pregnancy if the risk of Downs remains high.

Hope your query is answered.
Do write back in case of doubts.

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