Editing Prenatal testing (section)

{{Short description|Testing for diseases or conditions in a fetus}}
{{Use mdy dates|date=January 2025}}
{{Infobox diagnostic
| name = Prenatal testing
| image =Prenatal Down syndrome screening algorithm.png
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| caption =An example of an algorithm for prenatal testing for chromosomal abnormalities.<ref>Diagram by Mikael Häggström, MD, using following source: {{cite web|url=https://www.uptodate.com/contents/should-i-have-a-screening-test-for-down-syndrome-during-pregnancy-beyond-the-basics/print|title=Patient education: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)|website=UpToDate|author=Jacquelyn V Halliday |author2=Geralyn M Messerlian |author3=Glenn E Palomaki }} This topic last updated: February 16, 2023.</ref>
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| purpose = To monitor maternal and fetal health and progression, as well as, detect fetal abnormalities during pregnancy.
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| synonyms = Prenatal screening, prenatal diagnosis, genetic testing
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'''Prenatal testing''' is a tool that can be used to detect some [[birth defects]] at various stages prior to birth. Prenatal testing consists of '''prenatal screening''' and '''prenatal diagnosis''', which are aspects of [[prenatal care]] that focus on detecting problems with the pregnancy as early as possible.<ref>{{Cite web|url=https://medlineplus.gov/prenataltesting.html|title=Prenatal Testing |website=MedlinePlus}}</ref> These may be [[anatomy|anatomic]] and [[physiology|physiologic]] problems with the health of the [[zygote]], [[embryo]], or [[fetus]], either before [[gestation]] even starts (as in [[preimplantation genetic diagnosis]]) or as early in gestation as practicable. Screening can detect problems such as [[neural tube defect]]s, [[chromosome]] abnormalities, and gene [[mutation]]s that would lead to [[genetic disorder]]s and birth defects such as [[spina bifida]], [[cleft palate]], [[Down syndrome]], [[trisomy 18]], [[Tay–Sachs disease]], [[sickle cell anemia]], [[thalassemia]], [[cystic fibrosis]], [[muscular dystrophy]], and [[fragile X syndrome]]. Some tests are designed to discover problems which primarily affect the health of the mother, such as [[Pregnancy-associated plasma protein A|PAPP-A]] to detect [[pre-eclampsia]] or [[glucose tolerance test]]s to diagnose [[gestational diabetes]]. Screening can also detect anatomical defects such as [[hydrocephalus]], [[anencephaly]], [[Congenital heart defect|heart defects]], and [[Amniotic band constriction|amniotic band syndrome]].

Prenatal [[screening (medicine)|screening]] focuses on finding problems among a large population with affordable and noninvasive methods. Prenatal diagnosis focuses on pursuing additional detailed information once a particular problem has been found, and can sometimes be more invasive. The most common screening procedures are routine [[medical ultrasonography|ultrasounds]], blood tests, and blood pressure measurement. Common diagnosis procedures include [[amniocentesis]] and [[chorionic villus sampling]]. In some cases, the tests are administered to determine if the fetus will be aborted, though physicians and patients also find it useful to diagnose high-risk pregnancies early so that delivery can be scheduled in a [[health care#Tertiary care|tertiary care]] hospital where the baby can receive appropriate care.

Prenatal testing in recent years has been moving towards non-invasive methods to determine the fetal risk for genetic disorders. The rapid advancement of modern high-performance molecular technologies along with the discovery of [[cell-free fetal DNA]] (cffDNA) in maternal plasma has led to new methods for the determination of fetal chromosomal [[aneuploidies]]. This type of testing is referred to as [[Non invasive prenatal testing|non-invasive prenatal testing]] (NIPT) or as non-invasive prenatal screening. Invasive procedures remain important, though, especially for their diagnostic value in confirming positive non-invasive findings and detecting genetic disorders.<ref>{{Cite journal|last1=Pös|first1=Ondrej|last2=Budiš|first2=Jaroslav|last3=Szemes|first3=Tomáš|date=2019|title=Recent trends in prenatal genetic screening and testing|journal=F1000Research|volume=8|page=764|doi=10.12688/f1000research.16837.1|issn=2046-1402|pmc=6545823|pmid=31214330 |doi-access=free }}</ref> Birth defects have an occurrence between 1 and 6%.<ref>{{Citation |last1=Outcomes |first1=Institute of Medicine (US) Committee on Improving Birth |title=Impact and Patterns of Occurrence |date=2003 |url=https://www.ncbi.nlm.nih.gov/books/NBK222082/ |work=Reducing Birth Defects: Meeting the Challenge in the Developing World |access-date=2023-10-01 |publisher=National Academies Press (US) |language=en |last2=Bale |first2=Judith R. |last3=Stoll |first3=Barbara J. |last4=Lucas |first4=Adetokunbo O.}}</ref>

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