1 in 44 risk facotr for Trisomy 18

[nicomommy2005]

I am here looking for support. I had a sequental (sp?) screening done and the 2nd part came back suggesting I have a 1 in 44 chance of having a child with Trisomy 18. Is that high? How accurate are these kinds of blood tests? I am horrified and have been looking up info on it since I found out a couple of hours ago. The Dr. office cannot get me in until Monday, so needless to say I am walking on pins and needles. I don’t understand the kind of test this is. I have looked up info online, but some of the readings are confusing to me. For example, one stated this sort of test detects 90% of children with Trisomy 18. Is this true? I am due on Aug. 22, which makes me about 17 weeks. The nurse said I should have an amnio done, but isn’t an amnio done about 16 weeks? And, maybe I should have another ultrasound done to look for physcial features? I really need some advice. I cannot stop crying and I just don’t understand this. If they didn’t have this kind of test, the first part would have been the only test done, which would have came back fine. Now, they do a 2nd part and tell me something might be wrong with my child. What if I have the amnio done and nothing is wrong but it later causes problems with my pregnancy? I have all kinds of situations running through my head and I just don’t know what to think. I might add that I have had 2 ultrasounds b/c I see a specialist due to a previous miscarriage. I believe they are level 2 b/c I didn’t have to have a full bladder and could see the fetus clearly on 2 different screens in the room. Everything has been okay with development so far, and I am calculating right on schedule with time of conception and growth of fetus only b/c I know when I conceived. I thought this might help you understand my situation better. Please reply with any adivce.

[eureka254]

The sequential blood test is only a screening tool, and will not give you a definite diagnosis either way.  (The "90%" sensitivity means that 9 out of 10 women who are carrying a baby with Trisomy 18 will have an "increased risk" test result.  It does NOT mean that 9 out of 10 women with "increased risk" will have a baby with trisomy 18.) Keep in mind that if your risk is assessed as 1 in 44, the chances are still in your favor that your baby does not have trisomy 18.  Think of it as a greater than 97% chance that your baby does NOT have trisomy 18 (and, conversely, only a 2-3% chance that baby is affected).  

Whether or not to pursue amnio is a very personal decision, but it is the most reliable diagnostic test for detection of trisomy in pregnancy available today.  Technically, amniocentesis can be performed at any point during the pregnancy, but it is recommended most at 16-18 weeks for diagnostic/management purposes.  Like the blood test, ultrasound can provide additional information but will not determine the presence or absence of trisomy.  Depending on the experience of the physician, the risk of miscarriage due to amniocentesis is somewhere between 1 in 200 to 1 in 400 in most centers.  There is no evidence to suggest additional risks beyond the risk of infection/miscarriage associated with amniocentesis.

Has your OB referred you to a Genetic specialist? A consultation with a medical geneticist and/or genetic counselor may help you in your decision-making.  

Wishing you the best.
~eureka

[nicomommy2005]

No, I am seeing a high risk specialist so I am unsure if I'll need to see a gen. coun. also? I spoke to him last night and he said I could have the amnio done tomorrow or Friday, but I said I would wait until I have an u's and then deicde. So, Monday I go for an u/s. I guess we'll see what happens and go from there. THANKS so much for the reply!!

[eureka254]

Some High Risk OBs are very knowledgeable about genetics -- some not -- if your doctor inspires your confidence and is able to answer all your questions, you may not need to consult further.  

I hope your ultrasound goes well on Monday -- the sonographers should do a thorough job, especially in looking at fetal movement -- especially hand movements (some trisomy 18 babies have what is known as "clenched fists") -- and they should be looking closely at the cerebral (head/brain) area.

If you decide to do amniocentesis, you might want to ask your doctor about availability of a "preliminary" test called "FISH" (flourescence in-situ hybridization), which might give you some information within 24-72 hours, since sometimes amniocentesis results can take as long as 2 weeks or more.

I hope you get good news from this point forward!  

[nicomommy2005]

I went to the doc on Tuesday and the u/s showed nothing wrong with the baby. No markers were seen, and it looks like I'm having a boy (unless it was the cord). The tech and doc both agreed that baby looked great and everything was normal... 4 chambers in heart, no cysts, etc. We decided not to do the amnio and doc said he felt comfortable with that. He will see me back in 2 weeks to check again and we'll go from there.