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First Trimester Screening |
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What is first trimester screening?
First trimester screening is performed during the first 9-13 weeks during pregnancy. It is a non-invasive test to measure if a baby is at an increased risk for certain chromosomal disorders, such as Down syndrome, trisomy 18 or trisomy 13. The screening results allow patients to make an informed decision whether to undergo more evaluation and tests.
Accuracy
First trimester screening has been extensively studied and proven to detect 91% of Down syndrome pregnancies, and 95% to trisomy 18/13 pregnancies.
In the majority of cases, no increased risk is found and patients can be reassured that it is unlikely that their baby has Down syndrome or trisomy 18/13.
The decision to have a first trimester screening test is your personal decision. If these tests show an increased risk, it does not necessarily mean that your baby has a problem, only that further evaluation of your pregnancy is indicated.
However, a normal test does not eliminate the possibility that your baby may have Down syndrome, trisomy 18/13 or other chromosomal abnormalities, nor does the test eliminate the possibilities of birth defects, developmental delays and other disorders not detectable by first trimester screening. In addition, women carrying babies with other chromosomal disorders or birth defects may have a positive test.
How is it performed?
The screening consists of a blood test and ultrasound exam, both performed at Suburban Imaging. The blood test is taken between the gestational age of 9 weeks to 13 weeks 6 days. The ultrasound exam is scheduled between 11 weeks to 13 weeks 6 days.
During the blood test, a finger stick is performed to obtain a blood sample. The sample is applied to a special card and sent to a lab for analysis of two chemicals: free Beta human chorionic gonadotropin (free Beta), and pregnancy associated plasma protein-A (PAPP-A) which are normally found in the blood of all pregnant women.
Ultrasound uses sound waves to create pictures of the fetus and does not use x-rays for radiation. The ultrasound exam records a fetal heartbeat and determines gestational age. The amount of fluid accumulation behind the neck of the baby, called nuchal translucency (NT) is also measured.
To capture the images, a specially certified technologist will be moving a wand called a transducer over your abdomen. For good contact, a small amount of warm gel is spread on your skin. When the exam is over, the gel will be wiped off.
The data from the ultrasound exam will also be sent to the lab. The lab will combine the ultrasound data and the blood test data to estimate a specific risk for Down syndrome and trisomy 18/13. Your healthcare provider will contact you to discuss the results of the first trimester screening.
What is Down syndrome?
Down syndrome is a chromosomal disorder that causes physical and developmental delays and birth defects that may involve the heart and/or digestive tract. The degree of physical and mental delays for individuals affected by Down syndrome varies greatly. For some it is minimal, for others it is substantial.
Down syndrome affects approximately one in every 800 babies. Women age 35 and over and those with a previous child with Down syndrome are more likely to have a baby affected with Down syndrome. However, most cases of Down syndrome occur in women under age 35 because they have more babies overall.
What is trisomy 18 and trisomy 13?
Trisomy 18 and trisomy 13 are severe chromosomal disorders that cause profound developmental delays and multiple birth defects. Few trisomy 18 or trisomy 13 babies live longer than one year, though some of these babies do survive into childhood. Like Down syndrome, the chance to have a pregnancy with trisomy 18 or trisomy 13 increases with advanced maternal age.
First trimester screening is available at: Coon Rapids and Southdale |
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