Prenatal Genetic Testing-Should You Consider the Triple Screen?

It has been many years since I was an expectant mother. My son is now 6 years old and my daughter is 4 years old. During my pregnancy, I was not presented with the triple screen as an option. My blood was drawn with my consent but I was unclear of the reason until several weeks later when my results came back abnormal. My son had 1:6 odds of having Down Syndrome.

The triple screen is a test performed by taking the mother's blood during her 16^th-18^th week of pregnancy. Levels of the hormones HCG, AFP, and Estriol present in the mother's blood are taken and compared to what they should be in a healthy pregnancy for a woman of her age, ethnicity, and other factors. This level of the hormones is combined with those other factors to assign a number to the likelihood the child will have a genetic problem such as Trisomy 21, Spinal Bifida, Trisomy 18, and some other conditions. The number you receive should be similar to what is normal for your age group.

The triple screen is a screening test-not diagnostic. Because it is often misinterpreted as being diagnostic, the triple screen causes stress to those who receive bad odds and who believe it is diagnostic. My son's odds of Trisomy 21 were 1:6-meaning that if six babies were sitting the room with him only one of those six would actually have the condition. Because the odds were so extreme "the same was what would be expected with a 55 year old woman" (I was 26) the paper stated, I assumed he had the condition. I did not opt for an amniocentesis or any further testing other than an ultrasound that revealed a bright spot on his heart.

Three days before Christmas my son was born looking healthy. He did not have Down Syndrome and we were ecstatic. He did have another condition that I recently learned may have thrown the results of the screen.

The problem with this screening test is several conditions or circumstances can skew the odds. If the test is not performed during the 16^th-18^th week hormone levels may be different than what they should be. During the five months I spent waiting to learn if my son would have Down Syndrome, I found that bleeding can affect the test results. Many issues exist that can affect this prenatal screen that doctors are not always aware of.

At the time I had my triple screen test performed with my son (we avoided it with my daughter because I knew the test brought a lot of false positives and did not want to go through it again), we did not realize I have a condition that causes me to form benign and sometimes malignant growths. The geneticist of my children told me last week the fact that I had known benign tumors and possible breast cancer without question affected the test result. Also, my son had Cowden Syndrome as well since it is something beginning at conception and it may have skewed the odds.

The irony is I could have opted for an amniocentesis to calm my mind about my son having Down Syndrome. The result would have come back negative. I would have rejoiced at him being genetically normal only to learn he has Cowden Syndrome six years later.

I do not write this to encourage you not to be screened-the choice is yours and it is very personal. Be aware a positive or negative test may mean absolutely nothing. Do what decision you feel is right for you. Before opting for the test, ask yourself what you would do with the results? Would you terminate the pregnancy? Then an amniocentesis is warranted. If you would not terminate the pregnancy or opt for an amniocentesis due to the very small risk of rupture then it would be best to second guess having the initial screening done. The five months of wondering if my son had Down Syndrome were excruciating.