The Triple Screen
While most babies enter the world without complications, 3-4% of infants are born with birth defects. In some cases, couples have no reason to suspect a problem exists. The Triple Screen identifies increased risk of certain types of birth defects, providing vital information for important decisions regarding the management of pregnancy.
The Triple Screen isolates three substances:
- alpha-fetoprotein (AFP)
-
estriol (uE3)
-
human chorionic gonadotropin (hCG)
These substances (normally made by the developing fetus), are transported through the placenta into the mother's blood where they can be measured.
Results of these levels are reviewed in conjunction with the woman's age, weight and race, and age of the fetus, to calculate the risk of giving birth to a baby at higher risk for certain birth defects, such as:
- neural tube defects (abnormal opening of the skull or spine)
-
abdominal wall defects
-
Down's Syndrome or other chromosomal problems
The screen should be performed 15 -20 weeks past the first day of the woman's last menstrual period, with results compared to amounts normally present during pregnancy.* If risk is determined to be significant, additional testing may include detailed ultrasound, amniocentesis, and genetic counseling to provide more information about the baby. In most cases, the screen will be negative with no further testing required. Although this is reassuring, the initial negative screen does not rule out all birth defects. As the pregnancy progresses, the doctor will continue to gather additional information to monitor the normal progression of the pregnancy.
* Triple Screen interpretations are based upon results of assays performed by the University of Nebraska Clinical Laboratories in the Center for Human Genetics.
Date last updated: January 27, 2003
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