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How to detect Downs' syndrome in fetus during pregnancy?

Mar 2013
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Answered by
Practicing since : 1998
Answered : 5970 Questions
Dear Dr., I am 14 weeks pregnant with a background risk 1:53 of Down but adjusted to 1:215 (including blood work & Nuchal scan info: Free B-HCg:73.90 IU/I, PAPP-A 2.521 IU/I, NT: 1.80mm & CRL:62.6). I am 41 and will be 42 when I give birth. My husband is the same age. We have been trying for years to get pregnant so this IVF pregnancy is our little miracle. I do not know what any of these numbers mean i.e. if they are borderline, ok, low, reliable, ecc.. I unfortunately need to know if baby has Down or not & am considering an amnio but the advise has been contrary as I am considered 'low-risk'. My thoughts are to have another nuchal scan (2nd opinion) and triple screen blood test before scheduling amnio. Would you agree that I am low-risk and an amnio would be unnecessarily risky? Kind regards, concerned first mom-to-be
Posted Tue, 4 Mar 2014 in Pregnancy
Answered by Dr. Aarti Abraham 10 minutes later
Brief Answer: EXPLAINED BELOW Detailed Answer: Hello THanks for writing to us with your health concern. See, the adjusted risk takes into account all the factors - your age, the biochemical marker levels, ethnicity etc. You would be having the score of 1 : 53 , based on your age, I guess, but its the overall risk score that matters. Based on scientific evidence, you are low risk, so further invasive testing is not recommended. To reliably know if your baby has Downs' syndrome, amniocentesis is the only way out. IF you insist on it, you would get it done. I have to agree that you are low - risk, based on the reports, and hence amniocentesis would not be recommended to you by protocol. Also, know that amniocentesis would not pick up ALL chromosomal disorders that could be present in a baby due to age. All the best. Please feel free to discuss further.
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Follow-up: How to detect Downs' syndrome in fetus during pregnancy? 1 hour later
Dear Dr, Thank you for your response. I would like to better understand my testing results. What are the normal & Down ranges for CRL & NT and what are the normal & Down ranges for Free B-hsg & PAPP? You also did not comment on a 2nd nuchal scan by a different centre & the triple screen blood test & if having these results in addition could help a Dr. better determine if baby has Down without intrusive testing? What other chromosonal disorders could result due to age? Does the amnio not test for them all as I understood that amnio tests for many disorders in addition to Down? What does the amnio test for? Is there another test to consider then? If the amnio is positive, what are the chances that the baby doesn't have Down? If the amnio is negative, what are the chances that the baby has Down? What are the chances that the amnio is nonconclusive? I do understand that 1:215 is considered low risk by science & invasive testing is not recommended due to protocol but I a pregnant human not just a statistic and to me 1:1000+ is low risk not 1:200 so need additional information to assist with this very difficult and important decision. Thank you & kind regards, concerned first mom-to-be
Answered by Dr. Aarti Abraham 3 hours later
Brief Answer: EXPLAINED BELOW Detailed Answer: Hello I understand your apprehension. At no point did I mean that you were a statistic, its just that unfortunately , the reports that we have deal with statistics, and it is important to understand them. Let me elaborate. The CRL , NT and blood values together only SCREEN you for Downs. There is an accepted cut off level, say 1 : 150. If a lady has a risk higher than this , amniocentesis is recommended. If it is lower than this ( it could be 1 : 250 or 1 : 1000 ) , then it is accepted that the risks of amniocentesis outweigh the benefits of knowing the results. That is why further testing is not recommended for you. Now for your questions one by one - 1. Normally, NT values above 2.5 mm are considered high risk for Downs, but it is futile to comment on an isolated NT measurement, as the screening test is COMPREHENSIVE, not based on a single value. 2. Regarding the biochemical markers, Maternal serum markers (in this case the free beta-hCG and the PAPP-A) steadily change as the pregnancy progresses (i.e., by weeks' gestation) and these changes are quite significant during this early part of the pregnancy while the placental tissues are rapidly proliferating. During pregnancies in which the baby is chromosomally normal, the hCG levels begin to drop toward the end of first trimester and then level off and the PAPP-A levels tend to increase gradually throughout the pregnancy. In the case of a baby with Down syndrome (trisomy 21), the hCG levels are often elevated and the difference between chromosomally normal babies and those with Down syndrome increase as the pregnancy progresses. Because of the changes in serum marker levels by gestational age, for accurate interpretation of the test results, a different reference range must be used for each week of gestation, depending on when the test is drawn. To avoid the multiple reference range problems and also to standardize test results between different laboratories, whose reference ranges also vary, a MEDIAN value for test results in normal pregnancies is determined in each laboratory for each week of gestation. Then the values are expressed as multiples of that ' normal ' median. You have mentioned absolute results, not the MoM values, I would need those, and even then, it is to a point futile, because again, only the WHOLE combined risk matters, not individual markers. 3. A second nuchal scan and blood screen would be advised if you do not have faith in the first result, due to whatsoever reasons. 4. There is a long list of chromosomal disorders that could result due to advanced maternal age, most are rare, the commoner ones are Downs syndrome, Trisomy 13 and Trisomy 18. Amniocentesis tests for the latter three, not all of them. 5. There is no other test to consider, there is no test available in the world that can test for ALL possible chromosomal anomalies. 6. If the amniocentesis is positive, then chances are negligible that the baby wont have Downs. It is a very specific test in that sense, unlike the screening tests, which are not specific. 7. IF the amnio is negative, again, the chances of the baby having Downs are very low, since the test is quite specific. 8. Amniocentesis cannot be inconclusive for Downs, it will tell you either ways. At best, the NT and blood values give you an ESTIMATE of your baby having Downs. Based on the estimate, further testing is recommended. YOu do not come under that category, where further testing is warranted, however, it is an individual choice. If you want 100 % assurance and NOT an estimate, you have to choose . Hope this is a bit more helpful.
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Follow-up: How to detect Downs' syndrome in fetus during pregnancy? 23 hours later
Dear Dr. XXXXXXX Thank you for your response. It was very helpful. I believe this is my last question so I better make it a good one :) I'm including my MoM results so if you could shed any more light on these results, it would be greatly appreciated. Are the results borderline, well within range, ecc.? Free B-hCG 73.90 IU/I (equivalent to 1.876 MoM) PAPP-A 2.521 IU/I (equivalent to 0.902 MoM) I am 13 weeks and 1 day preganant. Since we exchanged emails, I have learned about Harmony and Panorama testing and although understand that as the Nuchal scan, these are not diagnostic tests (only CVS and Amnio are diagnostic) they appear to be highly reliable (although somewhat costly) non-invasive tests especially for Down syndrome, our main concern. What is your opinion on these tests and would you recommend one over the other? At this stage in the pregnancy, I also have been advised to ensure my EFAs are ok and linseed oil was recommended. I found a Holland & XXXXXXX cold-pressed flaxseed oil but the EFA levels seem quite high and there were 2 additional ingredients that worried me (Palmitic & Stearic Acids) especially as I am quite sensitive to preservatives. Would you agree with the linseed oil recommendation and do these levels look ok (directions: 1 tsp twice daily)? Is it ok for me & baby? H&B Flaxseed Oil: Alpha-Linolenic Acid 4,660mg Linoleic Acid, 1,128mg Oleic Acid 1,332mg Palmitic Acid 420mg Stearic Acid 252mg Again, thank you. This has been a great service and I plan to recommend it. Thank you and very kind regards, concerned mom-to-be
Answered by Dr. Aarti Abraham 1 hour later
Brief Answer: EXPLAINED BELOW Detailed Answer: Hello again. Thank you for your kind words. They mean a lot , when one strives to give the best of oneself . And by no means is this your last question, you should feel free to contact me directly on my profile anytime using the following link - WWW.WWWW.WW Now, for your values - B HCG > 2.5 MoM and PAPP-A < 0.4 MoM are worrisome, yours are normal in entirety. While the Harmony/ Panorama tests are not as specific as the amniocentesis, they are still much more accurate than the ultrasound / biochemical marker screen. If you can afford it, I would definitely recommend one of them. Which one - is a matter or choice, the difference lies only in the brands and the companies offering them, the basic premise and reliability is equally comparable. Regarding EFA, fish oil is anyday a better choice over flaxseed / linseed oil. Please go through the following link - WWW.WWWW.WW I can understand your apprehension regarding the prenatal testing, given your age, and I can also understand your efforts to test in whatever possible way you can. There is so much literature on the web regarding it, most of it scientific jargon, not easily comprehended by a non medical person. I am providing a link to a page that is concise and easy to understand , hopefully it should provide more clarity - WWW.WWWW.WW Trying to be to the point, if I could afford it, I would go for one of the two non invasive tests, those are quite reliable, and would save you the ordeal of an invasive test such as the amniocentesis. If those tests are fine, the odds of your STILL having a child with Downs syndrome are less than 1 %, which is the most that tests can do by way of reassurance. I hope this discussion was helpful. I would be happy to aid you anytime, and hence have provided you my profile link. Good day to you, and have a wonderful pregnancy and a fulfilling motherhood ! God bless.
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