Human chorionic gonadotropin hCG , a hormone made by the placenta when a woman becomes pregnant. Estriol uE3 , a form of estrogen that increases during pregnancy.
It is produced in large amounts by the placenta. Hormone inhibin A , a protein produced by the baby and the placenta. How is it done? A simple blood test is all that's needed for these tests. The health professional taking a sample of your blood will: Wrap an elastic band around your upper arm.
This makes the veins below the band larger so it is easier to put a needle into the vein. Clean the needle site with alcohol. Put the needle into the vein. Attach a tube to the needle to fill it with blood. Remove the band from your arm when enough blood is collected.
Put a gauze pad or cotton ball over the needle site as the needle is removed. Put pressure on the site and then put on a bandage. How accurate is it? The triple and quad tests correctly find neural tube defects, such as spina bifida, in 80 out of fetuses who have it and find anencephaly in about 90 out of fetuses. The triple test correctly finds Down syndrome in 69 out of fetuses who have it. It misses the condition in 31 out of fetuses.
It misses Down syndrome in 19 out of fetuses. What do the results mean? What do you do with the results? If you have a negative result, you may choose not to have another test. Learn how we keep our content accurate and up-to-date by reading our medical review and editorial policy. The educational health content on What To Expect is reviewed by our medical review board and team of experts to be up-to-date and in line with the latest evidence-based medical information and accepted health guidelines, including the medically reviewed What to Expect books by Heidi Murkoff.
This educational content is not medical or diagnostic advice. Use of this site is subject to our terms of use and privacy policy. Registry Builder New. The Quad Screen. Medically Reviewed by Jennifer Wu, M. Medical Review Policy All What to Expect content that addresses health or safety is medically reviewed by a team of vetted health professionals.
The quad screen tests four factors in your blood to help you make a decision about further genetic testing. Back to Top. In The Article. A false-positive result can cause stress and lead to unnecessary testing such as an amniocentesis. Many women who have a positive screening test result are actually carrying a healthy baby.
Sometimes negative test results can be wrong too. They may show that the baby is fine when he or she does have a birth defect. This is a false-negative test result. Your doctor will use your age and your baby's age to interpret the test results. If your test results are abnormal, your doctor may use a fetal ultrasound to make sure of your baby's age. A "positive" result means that there is a higher-than-average chance your baby has a birth defect.
If the result is "negative," or normal, it means that your baby probably doesn't have a birth defect. But it doesn't guarantee that you will have a normal pregnancy or baby. Your doctor may tell you the result of your test as a set of numbers. Doctors often use a certain number as a cutoff for a positive result.
For example, your doctor may say the cutoff is 1 out of This means that if your result is 1 out of or 1 out of a number less than such as 1 out of , you have a positive result and your baby has a higher chance of a birth defect. If your result is 1 out of , this means that you have a negative result and your baby has a lower chance of a birth defect.
If you have a positive test result, your doctor may want you to have the diagnostic test amniocentesis to find out for sure if there is a problem. But it's your choice whether to have another test. If you have a negative result, you may choose not to have another test. Deciding whether to have a test for birth defects is a personal decision. And it can be a hard choice. You need to think about what the results of a test would mean to you and how they might affect your choices about your pregnancy.
If you choose to have a test, you may want to talk with a genetic counsellor. The counsellor can talk with you about the reasons to have or not have the test.
He or she can also help you find other resources for support and decision-making. The quad screen — also known as the quadruple marker test, the second trimester screen or simply the quad test — is a prenatal test that measures levels of four substances in pregnant women's blood:. Ideally, the quad screen is done between weeks 15 and 18 of pregnancy — during the second trimester.
However, the procedure can be done up to week The quad screen is used to evaluate whether your pregnancy has an increased chance of being affected with certain conditions, such as Down syndrome or neural tube defects.
If your risk is low, the quad screen can offer reassurance that there is a decreased chance for Down syndrome, trisomy 18, neural tube defects and abdominal wall defects. If the quad screen indicates an increased chance of one of these conditions, you might consider additional screening or testing. The quad screen evaluates your chance of carrying a baby who has any of the following conditions:.
The quad screen has traditionally been one of the most commonly used screenings in the second trimester. It was generally used if prenatal care began during the second trimester or if first trimester screening, which involves a blood test and an ultrasound exam, wasn't available. Your health care provider might combine the results of first trimester screening with the quad screen to improve the detection rate of Down syndrome. Prenatal cell-free DNA screening is another screening method that your health care provider might recommend in place of quad screening.
Talk to your health care provider about your screening options. A negative quad screen doesn't guarantee that the baby won't have a chromosomal abnormality, single-gene disorder or certain birth defects.
If your screening test is positive, your doctor will recommend additional testing to make a diagnosis. Before the screening, think about what the results mean to you. Consider whether the screening will be worth any anxiety it might cause, or whether you'll handle your pregnancy differently depending on the results.
0コメント