Editing Down syndrome (section)

====Combinations====
{| class="wikitable"
|+ First- and second-trimester screening<ref name=ACOG2007>{{cite journal | title = ACOG Practice Bulletin No. 77: screening for fetal chromosomal abnormalities | journal = Obstetrics and Gynecology | volume = 109 | issue = 1 | pages = 217–227 | date = January 2007 | pmid = 17197615 | doi = 10.1097/00006250-200701000-00054 | author1 = ACOG Committee on Practice Bulletins }}</ref>
|-
!Screen
![[Gestational age (obstetrics)|Week of pregnancy]] when performed
!Detection rate
!False positive
!Description
|-
|Combined test
| 10–13.5&nbsp;wks
| 82–87%
| 5%
|Uses [[ultrasound]] to measure [[nuchal translucency]] in addition to blood tests for free or total beta-hCG and [[pregnancy-associated plasma protein A|PAPP-A]]
|-
|[[Quad screen]]
|15–20&nbsp;wks
|81%
| 5%
|Measures the maternal serum alpha-fetoprotein, unconjugated estriol, hCG, and [[inhibin]]-A
|-
|Integrated test
|15–20&nbsp;wks
|94–96%
|5%
|Is a combination of the quad screen, PAPP-A, and NT
|-
|[[Cell-free fetal DNA]]
|From 10&nbsp;wks<ref name=oxhp>{{cite web|title=Noninvasive prenatal diagnosis of fetal aneuploidy using cell-free fetal nucleic acids in maternal blood|url=https://www.oxhp.com/secure/policy/noninvasive_prenatal_diagnosis_fetal_aneuploidy.pdf|publisher=United Healthcare Oxford|access-date=25 March 2014|url-status=live|archive-url=https://web.archive.org/web/20140307093626/https://www.oxhp.com/secure/policy/noninvasive_prenatal_diagnosis_fetal_aneuploidy.pdf|archive-date=7 March 2014}}</ref>
|96–100%<ref name="Mersy 318–29">{{cite journal | vauthors = Mersy E, Smits LJ, van Winden LA, de Die-Smulders CE, Paulussen AD, Macville MV, Coumans AB, Frints SG | display-authors = 6 | title = Noninvasive detection of fetal trisomy 21: systematic review and report of quality and outcomes of diagnostic accuracy studies performed between 1997 and 2012 | journal = Human Reproduction Update | volume = 19 | issue = 4 | pages = 318–329 | date = Jul–Aug 2013 | pmid = 23396607 | doi = 10.1093/humupd/dmt001 | doi-access = free }}</ref>
|0.3%<ref>{{cite journal | vauthors = Bianchi DW, Parker RL, Wentworth J, Madankumar R, Saffer C, Das AF, Craig JA, Chudova DI, Devers PL, Jones KW, Oliver K, Rava RP, Sehnert AJ | display-authors = 6 | title = DNA sequencing versus standard prenatal aneuploidy screening | journal = The New England Journal of Medicine | volume = 370 | issue = 9 | pages = 799–808 | date = February 2014 | pmid = 24571752 | doi = 10.1056/nejmoa1311037 | doi-access = free }}</ref>
|A blood sample is taken from the mother by [[venipuncture]] and is sent for DNA analysis.
|}