Problems With Genetic Tests
10 Replies
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I was hoping someone could help me. I am such an emotional wreck right now.
At 12 weeks I was sent to a prenatal specialty lab to have the NT Screening performed. The results from that test came back very reassuring. My risks for downs syndrome based on that test was 1 out of 2701. The genetic counselor scheduled me for the followup 16 week genetic sonogram and the modified sequential blood test. Just days before I had the tests done at the prenatal lab, my doctor took blood for an AFP test. The prenatal lab instructed me not to have the AFP test done if I was having the modified sequential test done. My doctor went ahead and did the AFP test anyway.
I went to have the genetic sonogram and the modified sequential blood test just a few days later. I informed the lab that my doctor went ahead and did the AFP test and the lab told me they did not want me to have that test because there is a high rate of false positives.
So now here come the results..........my doctor received the results of my AFP test and they claim my risk of downs syndrome is 1 out of 55, which means according to that test my baby has a 2 percent chance of having downs syndrome. The results from my genetic sonogram combined with my modified sequential blood test shows that my baby has a 1 out of 14,500 chance of downs syndrome. The modified sequential blood work also included my AFP levels, which turned out to be normal.
My doctor is questioning why there is such a vast difference in test results and the pre natal lab is telling me that their tests are far more advanced and accurate than just a simple AFP test alone. The pre natal lab told me that my baby is completly healthy and my risks are better than the risks of a 20 year old.
Do I take that 2 percent risk seriously enough to have an amnio performed???? My doctor told me there is a 2 percent risk of miscarriage. I could never forgive myself if I found out my baby was normal but due to the test I had a miscarriage. The worst test result (AFP test) shows my baby is 98 percent healthy, and the best test results shows my baby is above normal.
Please help!
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Ttat is a tough one...I am sure you are feeling very upset with these discrepancies.. The large difference from the 1:14500 to 2% seems like a huge variable that should not be ignored. you can't take these things lightly. You must ask yourself the question..in the end..if your baby was to be born with downs..would you want to keep him/her. If you would either way than I would not opt for any chance on taking the amnio..but again..the amnio is a very fast an simple test that is done routinely..and may give you the answer you desire..and you will be able to enjoy the rest of your pregnancy. Your likelihood of anything be wrong is still VERY unlikely but peice of mind is everything. I wish you all the best..Just remember the percentage is not so directed at your baby but other babies born that had similar percentiles and then were born with downs. I wish you all the best..LEt us know your decsion..and I am sure you will have alot of good advice from prefessionals that will be able to guide you. :)
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Thank you Kristen72 for your response. I am going to call the genetic counselor at the pre natal lab today to discuss the reasons for the discrepancies. When I spoke to the counselor yesterday she was very confident that their results were more accurate. When I looked at the results from the blood work from the pre natal lab it showed one of the things they tested for was my AFP level, which was normal. Maybe it's possible that two different labs use different calculations to access risk factors.
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| K - September 5 |
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I would not have the amnio. Based on what my doctor told me, I don't think yours is up on all the tests and the problems with them. Since you are posting on the over 35 board, I am a__suming that you are over 35. When I was pg, my doctor recommended that I not do the AFP test. She says that test will never come back normal on women over 35, and that they have healthy babies all the time. She explained it to me and I can't remember it all, but apparently even when your AFP level is normal the test takes "age" and maybe other non- specific factors and adds risk because of them, and simply based on those will not give you a normal result. She did not think the AFP test was worth anything for women over 35. She thinks some doctors do them on women in that age group just so they can recommend amnios and make more money. She also suggested no amnio, because even though the risk is very small, it is still there. (In your situation if a 2% risk of harm is so small that your Dr. thinks you should do the amnio, then why is a 2% risk of downs on the AFP large enough that they want to do one? ) Her course for her patients in our age group is to send us to a Level 2 ultrasound with a high risk pregnancy specialist. If the results are not completely normal, then she will sit down with her patients and discuss doing an amnio or further testing. My results were normal , we did no further testing, and dd is healthy.
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Hello K,
The genetic lab also told me not to have the AFP testing done, but my doctor went ahead and did it anyway. I just got off the phone with the genetic counselor and she said their results are based on comparing my 12 week tests combined with my 16 week tests (blood and sono's) and that is how they come up with the final risk a__sessment. She also rea__sured me that my baby is at no risk of having any abnormalities so I am not going to do the amnio. Too many false or abnormal readings are the reasons why the genetic lab does not perform the AFP test in the first place.
Oh, and yes, I am over 35. I am going to be 38 in just a few weeks.
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Hi there. I was given a result of 1/22 for DS. I was 38 years old and pregnant with my 4th child. My NT scan at 12 weeks was fine. I gave blood at 12 weeks and at 16 weeks. I declined the amnio as there is a risk of miscarriage. I know thats its very small risk, but it is a risk and baby could be lost. So it was a very long wait from 16 weeks to 37 weeks when she was born. I did take advantage of the 20 week anatomy scan and had her heart checked throughly by a fetal medicine specialist. She had no physical markers for DS, we just had these very high DS score. So, we waited and waited. At 37 weeks she was born and the peds looked at her and did not think she had DS. They used her blood from the umbilical cord and sent it in for the proper genetic test on her. It confirmed she did not have DS. My specialist and many others believe that these high readings pointing at DS are actually indeed due to placental issues instead. NOT DS but issues within your placenta. My advice to you would be to hang in there. Try not too worry, but I know personally what you are going through. Get yourself in to see a fetal medicine specialist and have a scan done and also have your plactal function monitered. There may be an underlying issue there masking as DS. Google and you will see a ton of papes written by speialists within the American Journal of Medicine about how these tests are placenta related and falsly point at DS. I doubt a regular OB would be up on all this. I went to an downtown high risk centre in Toronto and my dr was brillliant. Good luck and my heart goes out to you. It was 1 yr ago this week that I received that same call. Hugs.
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Dear blesswith4,
Thank you very much for your advice. I had also read that there are several different reasons for an afp test to come back with a "false positive", including placenta issues. My mother had preclamsya with her pregnancies, but still had healthy babies. Maybe I am at risk for develping preclamsya also? I will be going for my level 2 ultrasound in 2 weeks at the pre natal genetic lab. I will talk to them about seeking the a__sistance of a fetal medicine specialist. Thank you again for the great advice!
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Years ago they had no idea that the root of preeclampsia is placental ppor function. Many regular OB's to this moment are still unaware of the latest research. Specifically find a fetal med dr with preclampsia as his/her sub speciality. After my first child and it being so severe, the regular dr told me no more babies. After finding this new incredible dr I went on to have 3 more. They detected the poor uterine artery flow at 16 weeks and I had 3 more healthy baby. the thing with these certain placental tests, the uterine artery (jusyt a specific scan) has to be done between 16 and 20 weeks to get the best view. Best of luck.
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One more thing, this same dr also told me that my kids should also mention when they are older giving birth themselves that I had preeclampsia. I am a__suming there is some heritariness involved.
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I just called my doctor today after reading your post. I let him know that my mom suffered from preeclamsia when she was pregnant. He will keep a watch out for it when I come see him for my appointments. So far my blood pressure and urine has been normal, but I also read that preeclamsia does not really set in until after week 20.
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hey there. yes its after 20 weeks. the first time mine was at 24 weeks and then 36. usually regular hosiptals and clinics don't do the uterine artery scan, its done in a fetal medicine clinic. If that scan is normal between 16 and 20 weeks chances are all will be fine. good luck and glad i could help a little.
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