At What Point in a Pregnancy Can You Tell if the Baby Has Downs Syndrome

March 11, 2022 Post a Comment

Wellness care providers tin check for Down syndrome during pregnancy or after a child is born. At that place are 2 types of tests for Down syndrome during pregnancy:

A prenatal screening examination. This examination tin can show an increased likelihood that a fetus has Down's syndrome, simply it cannot determine Down syndrome is definitely present. If a screening test shows an increased likelihood, a diagnostic test can be ordered.
A prenatal diagnostic test. This test can determine with certainty that Down's syndrome is present. Diagnostic tests carry a slightly greater risk to the fetus than do screening tests.

The American Congress of Obstetricians and Gynecologists (ACOG) recommends that all meaning women exist offered a Down's syndrome screening exam.¹

Prenatal Screening for Down's syndrome

There are several options for Down syndrome prenatal screening. These include:

A blood test and an ultrasound test during the kickoff trimester of pregnancy. This is the virtually accepted approach for screening during the kickoff trimester. A blood test enables a health care provider to cheque for "markers," such equally certain proteins, in the mother'south blood that propose an increased likelihood of Downwardly syndrome.² Then the health intendance provider does an ultrasound test, which uses high-frequency sound waves to create images. An ultrasound can notice fluid at the back of a fetus'due south neck, which sometimes indicates Down's syndrome. The ultrasound test is called measurement of nuchal translucency. During the first trimester, this combined method results in more constructive or comparable detection rates than methods used during the 2nd trimester.^three
A blood test during the 2d trimester of pregnancy. Equally in the first trimester, a claret exam enables a wellness care provider to cheque for markers in the mother's blood. A triple screen looks for levels of three different markers; a quadruple screen looks for levels of 4 unlike markers.^iii,4
A combined exam (sometimes called an integrated test). This approach uses both a blood test and an ultrasound during the first trimester as well as a second-trimester blood test. Health care providers then combine all these results to produce 1 Down's syndrome risk rating.²

If a woman is pregnant with twins or triplets, a blood test will not be equally reliable considering the substances from a Down's syndrome fetus may be harder to detect.^2,three

Prenatal Diagnostic Testing for Down Syndrome

If a screening exam suggests the likelihood of Down syndrome, a diagnostic test can be performed. ACOG recommends that pregnant women of all ages exist given the pick of skipping the screening test and getting a diagnostic examination first. Until recently, merely women over age 35 and other at-take a chance women were offered this choice considering diagnostic tests carry a slight hazard of miscarriage.ⁱ Before having diagnostic testing, a pregnant woman and her family may desire to see with a genetic counselor to discuss their family history and the risks and benefits of testing in their specific situation.

Diagnostic testing for Down syndrome involves removing a sample of genetic cloth. After it is removed, the sample is checked for extra textile from chromosome 21, which may indicate that a fetus has Down syndrome. Parents normally get the results of the exam a week or two later. The following procedures are used to extract samples.

Amniocentesis (pronounced am-nee-oh-sen-TEE-sister). A wellness care provider takes a sample of amniotic (pronounced am-nee-OT-ik) fluid, which is then tested for the extra chromosome. This test cannot exist done until week 14 to 18 of the pregnancy.
Chorionic villus (pronounced KOHR-ee-on-ik VIL-uhs) sampling (CVS). A wellness care provider takes a sample of cells from a role of the placenta (pronounced pluh-SEN-tuh), which is the organ that connects a woman and her fetus, and then tests the sample for the extra chromosome. This test is done between weeks ix and 11 of pregnancy.
Percutaneous (pronounced pur-kyoo-TEY-nee-uhs) umbilical blood sampling (PUBS). A wellness care provider takes a sample of fetal blood in the umbilical string through the uterus. The blood is then tested for the actress chromosome. PUBS is the most authentic diagnostic method and can confirm the results of CVS or amniocentesis. Still, PUBS cannot be performed until later in the pregnancy, during the 18th to 22nd week.⁵

Prenatal diagnostic testing does involve some chance to the mother and fetus, including a slight risk of miscarriage.^6,vii,8,9 If you and your family are because prenatal diagnostic testing for Down syndrome, discuss all the risks and benefits with your health care provider.

Chromosomal Testing of Maternal Blood

A significant adult female who is at chance for having an infant with Down syndrome also can accept a chromosomal test using her claret. A mother'southward blood carries DNA from the fetus, which may testify extra chromosome 21 cloth.^three A more than invasive exam then would unremarkably confirm the blood exam.

Testing and In Vitro Fertilization

Some other approach to diagnosis is used in conjunction with in vitro fertilization. Preimplantation genetic diagnosis (PGD) allows clinicians to observe chromosome imbalances or other genetic weather condition in a fertilized egg before it is implanted into the uterus.

This technique is useful mostly for couples who are at take a chance of passing on a multifariousness of genetic conditions, including X-linked disorders, likewise equally couples who take suffered repeated spontaneous pregnancy losses, sub-fertile couples, or those at risk for single-gene disorders.

Those interested in PGD should have genetic counseling and should consider shut monitoring and additional testing during their pregnancies, given some increased hazard of chromosomal abnormalities arising secondary to the in vitro fertilization process.¹⁰

Diagnosis of Down Syndrome After Nascence

A diagnosis of Down syndrome after birth is often based initially on concrete signs of the syndrome.

Simply because individuals with Down syndrome may not take these symptoms, and because many of these symptoms are mutual in the general population, the wellness intendance provider will take a sample of the baby's blood to ostend the diagnosis. The blood sample is analyzed to determine the number of the baby's chromosomes.^xi

Citations

Close Citations

American Congress of Obstetricians and Gynecologists (ACOG). (2007, May seven). ACOG's screening guidelines on chromosomal abnormalities [News release]. Retrieved June 11, 2012.
Driscoll, D. A., & Gross, S. (2009). Prenatal screening for aneuploidy. New England Periodical of Medicine, 360, 2556–2562.
Ehrich, M., Deciu, C., Zwiefelhofer, C., Tynan, J. A., Cagasan, L., Tim, R., Lu, V., et al. (2011). Noninvasive detection of fetal trisomy 21 by sequencing of Dna in maternal blood: A study in a clinical setting. American Periodical of Obstetrics & Gynecology, 204, 201–211.
ACOG. (2011). Routine tests in pregnancy. Retrieved June 11, 2012, from http://www.acog.org/~/media/For%20Patients/faq133.pdf?dmc=1&ts=20120611T1510306056 (PDF - 218.20 KB)
American Association for Clinical Chemistry. (2012). 2nd trimester: Cordocentesis (percutaneous umbilical blood cord sampling, PUBS). Retrieved June 11, 2012, from https://labtestsonline.org/atmospheric condition/pregnancy-2d-trimester-thirteen-27-weeks
Caughey, A. B., Hopkins, L. M., & Norton, Chiliad. E. (2006). Chorionic villus sampling compared with amniocentesis and the difference in the charge per unit of pregnancy loss. Obstetrics and Gynecology, 108, 612–616.
Evans, M. I., & Wapner, R. J. (2005). Invasive prenatal diagnostic procedures 2005. Seminars in Perinatology, 29, 215–218.
Daniilidis, A., Karydas, H., Zournatzi, V., Tantanasis, T., Giannoulis, C., & Tzafettas, J. (2008). A four-twelvemonth retrospective study of amniocentesis: One eye experience. Hippokratia, 12, 113–115.
ACOG. (2007). ACOG Exercise message: Invasive prenatal testing for aneuploidy. Retrieved June eleven, 2012, from https://www.ncbi.nlm.nih.gov/pubmed/18055749 (PDF - 160 KB)
Hanna, K. East. (2006). Reproductive genetic testing. Retrieved June 11, 2012, from the National Homo Genome Research Institute website: http://world wide web.genome.gov/10004766
National Human Genome Inquiry Constitute. (2010). Learning nigh Down's syndrome . Retrieved June 11, 2012, from http://www.genome.gov/19517824#3