Editing Down syndrome (section)

==== Ultrasound ====
[[Prenatal ultrasound]] can be used to screen for Down syndrome. Findings that indicate increased chances when seen at 14 to 24 weeks of [[gestation]] include a small or no nasal bone, [[ventriculomegaly|large ventricles]], [[nuchal fold thickness]], and an abnormal right [[subclavian artery]], among others.<ref name=Aga2013>{{cite journal | vauthors = Agathokleous M, Chaveeva P, Poon LC, Kosinski P, Nicolaides KH | title = Meta-analysis of second-trimester markers for trisomy 21 | journal = Ultrasound in Obstetrics & Gynecology | volume = 41 | issue = 3 | pages = 247–261 | date = March 2013 | pmid = 23208748 | doi = 10.1002/uog.12364 | doi-access = free }}</ref> The presence or absence of many markers is more accurate.<ref name=Aga2013/> Increased fetal [[nuchal translucency]] (NT) indicates an increased possibility of Down syndrome picking up 75–80% of cases and being falsely positive in 6%.<ref>{{cite journal | vauthors = Malone FD, D'Alton ME | title = First-trimester sonographic screening for Down syndrome | journal = Obstetrics and Gynecology | volume = 102 | issue = 5 Pt 1 | pages = 1066–1079 | date = November 2003 | pmid = 14672489 | doi = 10.1016/j.obstetgynecol.2003.08.004 | s2cid = 24592539 }}</ref>

<gallery mode="packed" heights="200px">
T21.JPG|Ultrasound of fetus with Down syndrome showing a [[megacystis|large bladder]]
Nuchal edema in Down Syndrome Dr. W. Moroder.jpg|Enlarged NT and absent nasal bone in a fetus at 11 weeks with Down syndrome
</gallery>