-
Prospective validation of first-trimester combined screening for trisomy 21.
Kagan KO, Etchegaray A, Zhou Y, Wright D, Nicolaides KH.
Ultrasound Obstet Gynecol 2009;34:14-8. -
Screening for trisomy 21 by fetal tricuspid regurgitation, nuchal translucency and maternal serum free beta-hCG and PAPP-A at 11 + 0 to 13 + 6 weeks.
Falcon O, Auer M, Gerovassili A, Spencer K, Nicolaides KH.
Ultrasound Obstet Gynecol 2006;27:151-5.