Should I go for amniocentesis to check for abnormalities in the fetus?

Q: I am 32 years old and 18 weeks pregnant. I received my ultrasound results and the doctor informed me that they had detected ecogenic intracardial foci (EIF) in my baby's left ventricle, which is a marker for Down's Syndrome/Trisomy 18. My doctor suggested that I schedule for an amniocentesis as soon as possible, even without waiting for the triple test results. I have scheduled my amnio next week, which is when I get my triple screen test results. I read about the EIF and found that this marker was commonly seen in Asians (30%) and was a soft marker but it did not pose a high-risk (about 1 in 236, I think) in women aged 32 or younger, but the risk increases at 33. But both my husband and I have been quite nervous and worried since then. It appears that the statistics are in our favour, but we may not be at peace until we go ahead with the amnio. But amnio itself has risks of miscarriage. Is the amnio justified in my case?

A:I am happy that you have read as much about soft markers and the associated risks of Down's syndrome, as you obviously have. This is the need of the hour and all pregnant women need to educate themselves as much as you have, especially since pregnancy is often over-medicalised these days. You need this self education to understand all aspects of prenatal diagnosis before you make an informed decision and be able to participate fully and responsibly in deciding the course of your pregnancy. Unfortunately, when your own pregnancy is involved it is impossible to be completely objective, since fear of having an abnormal child is the dominant emotion with you and your husband right now. Over and above what you already know about the Down's syndrome risk, I want to warn you that the diagnosis on ultrasound may not be perfect. Besides causing a lot of anxiety, the problem of these soft markers are that they are being over-diagnosed, meaning that they are reported when they do not really exist. So observer error is a distinct possibility. Ultrasound reports are never absolute. They generally deal with possibilities rather than a diagnosis in black and white of normal/abnormal. This is partially because the technology itself has inherent limitations and it may sometimes be because of an overenthusiastic effort at making a diagnosis. The Ultrasonologists do not want the disgrace of missing a marker or being labelled not as good at picking up abnormalities as the other guy. There seems to an ongoing race amongst ultrasound specialists to be the best in the market. The other problem is the ultrasonologist should not prescribe interventions like amniocentesis. While it is his/her job to pick up abnormalities and markers, the interpretations or the need for interventions like an amniocentesis should be left to a fetal medicine specialist. Since there are few fetal medicine specialists and the general obstetricians may not be very well versed with interpretations of these findings, such confusions occur. The problem at hand is whether to get an amniocentesis done or not. Well this is tough and you have to take a decision yourself based on your outlook in life. Your query is quite simple, is the risk of having a Down's baby greater or the possibility of aborting a perfectly normal fetus. Both the risks are real and you need to take a decision now based on the best available evidence.At this stage as you know EIF in a woman of Asian origin is considered of unknown significance. With the current state of medical knowledge, we do not know whether there is a significant increase in the risk of Down's (or Trisomy 18) or not. In fact most people would not even mention a finding like that to the patient if they were sure that this is the only abnormality, especially if it is in the left ventricle (it is mostly in the left side and the association with Down's syndrome is more if it is in the right ventricle or in both ventricles).What is more important at this stage is what we call risk perception of the couple involve (in this case, you and your husband). Whenever you talk to a genetic counsellor, they are going to give you a statistical figure like 1:200, 300 or 400 etc. Statistics do not matter if you get a normal baby and also not to the mother of the one who happens to be that one in 200 or 400. Now that the alarm has been raised, it all boils down to what you think is an unacceptable risk? If you can take a 1% risk of an abortion of a possibly normal baby you need to get the amniocentesis done. The advantage is that you will get a definite answer whether the fetus is normal or not. I want you to understand that an amniocentesis will rule out chromosomal abnormalities only and not all possible abnormalities that can be present in a fetus. There is also a lab failure meaning that you may not get a complete report and the tissue cultures may fail. All this depends on the labs and their success rates. Please ensure that whoever does an amniocentesis is a fetal medicine consultant and the lab, the fluid is sent to, is good. On the other hand, if you want to wait for the triple test report and other tests, like a repeat detailed scan at 22 weeks to decide, in which case there is no way you will get a definite yes/no answer and you will have to leave things to God at least in that one in 300/400 or whatever may be the case. This may or may not be acceptable to you. Please consider all this and make your decision. Either way there is no hurry and please do not take a hasty decision which you may regret later. We make decisions in anticipation and analyse them in retrospect when everyone is wiser and can turn around and say look you should have done this or that. I cannot help you more than this, as you will have to take your own decision.