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Screening for trisomy 18 by fetal nuchal translucency and maternal serum free beta -hCG and PAPP-A at 10-14 weeks of gestation.
Tul N, Spencer K, Noble P, Chan C, Nicolaides K.
Prenat Diagn 1999;19:1035-42. -
Assessment of umbilical arterial and venous flow using color Doppler.
Lees C, Albaiges G, Deane C, Parra M, Nicolaides KH.
Ultrasound Obstet Gynecol 1999;14:250-5.