5Trunca L. The chromosome syndromes [J]. Brunner/mazel, 1980,11:188.
6Weisz B,Pandya PP,David AL,et al.Ultrasound findings after screening for down syndrome using the integrated test.Obstet Gynecol,2007,109(5):1046-1052.
7Karen F,Brian JK.Ultrasound and fetal diagnosis.Curr Opi Obs & Gyn,2005,17(2):1855.
8Van den H of MC,Wilson RD.Diagnostic Imaging Committee,Society of Obstetricians and Gynaecologists of Canada,et al.Fetal soft markers in obstetric ultrasound.J Obstet Gynaecol Can,2005,27(6):592-636.
9Bethune M.Literature review and suggested protocol for managing ultrasound soft markers for Down syndrome:thickened nuchal fold,echogenic bowel,shortened femur,shortened humerus,pyelectasis and absent or hypoplastic nasal bone.Australas Radiol,2007,51(3):218-225.
10Benacerruf BR.The role of the second trimester genetic sonogram in screening for fetal Down syndrome.Semin Perinatol,2005,29(6):386-394.