The question: Help! I had an AFP test which came back positive. I had an amnio yesterday and have to wait 8-12 days for the results. I'm really worried. - Marie
The expert answers: The Alpha Feta Protein test is a blood test done at about 16 weeks of pregnancy which gives us an idea of the risk of the fetus having a neural tube defect such as spina bifida. There is also another testing being used called the Triple Screen. This takes the alpha feta protein and combines it with other factors and gives you a result that also tells you if you might be at risk for other problems such as Down Syndrome or the other trisomies. You mention a "positive" result. What this tells us is not whether or not there is a problem with the fetus but whether or not you are at increased risk for a problem.
Age is a very big factor in these results, and they can be affected by other maternal influences also. One thing to be considered is what the actual numbers are. Is the result extremely high or just a little elevated? There is also the possibility of a false positive result. After a positive result, the next step is amnio, or at the very least, an anomaly screening ultrasound.
There is another consideration here which gets into the realm of ethics and I am not going to dwell on it. Whether or not you go on with further testing is entirely up to you. If your beliefs would stop you from terminating a pregnancy because a child would be deficient in some way, then you might want to consider whether or not you need to do any further testing. This is a very personal decision and should be left to the patient and her personal support structure with the appropriate input from the caregiver.
Amniocentesis will give you the most answers but it does not come without slight risks itself. Anytime, a procedure is "invasive" there is risk of bleeding, infection and injury but the risk is very slight. You would know the sex of the baby if you choose and whether or not there are any neural tube defects, trisomies or other genetically related problems. This can be wonderful knowledge to have as you proceed with your pregnancy and can be most reassuring. Physical deformities would not show on an amniocentesis but can usually be seen on the accompanying ultrasound.
An anomaly screening ultrasound is a detailed ultrasound which is done usually at the office of a perinatologist. They look for very specific physical things on the fetus which could indicate a problem. For instance, a fetus with Down Syndrome usually has thickened pad of fat at the back of the neck and certain features of the hands. A baby with spina bifida would have an opening in the spinal cord that would be seen on the ultrasound. The heart can be looked at and each of the chambers viewed. Kidneys and ureters can be checked. A lot can be seen on these ultrasounds, but while they are not as conclusive as the amniocentesis, they do give us a lot of information.
Good luck on a continuing healthy pregnancy!