What is AFP and the Triple Screen?
Screening tests are designed to identify a person who may have the possibility of a disease. If positive, the person requires further testing for diagnosis which is more sensitive and specific. Alpha-fetoprotein (AFP) is a screening test for conditions known as neural tube defects such as spina bifida (spinal cord development disorder) and anencephaly. This test also screens for Down’s syndrome. AFP is part of a group of blood tests known as maternal serum triple or quadruple screening which is usually done during the second trimester between 15 and 20 weeks. The triple screen checks levels of AFP and the hormones, hCG (human gonadotropin), and estriol (estrogen). The quad screen is more specific and includes inhibin A hormonal levels plus the three. The results of these tests are calculated by the blood level of each and adjusted to the women’s age, gestational age, pregnancy weight, race, diabetic status, and if there are multiples..
Reasons to consider the AFP screen
•The AFP is a noninvasive screening test that give information regarding possible birth defects.
•The quad screen helps in identifying pregnancies at risk for Down’s Syndrome, and has a lower false positive rate.
Risks of AFP
•AFP is not a specific test and further diagnostic testing, such as amniocentesis, is recommended for diagnosis if there are positive results.
•Cause of anxiety and worry with false positive results.
•Many women over age 35 have received false-positive results because the test factors in a women’s age. Ultimately, many of these women gave birth to healthy babies. .
Although this test is a simple blood test, it carries a risk of false positive results leading to high anxiety. I would only recommend this test for women who could consider having further testing such as amniocentesis or in depth ultrasound for definitive diagnosis.
Copyright © 2008 Dr. Feder - All Rights Reserved