2Oh JS, Wright G, Coulam CB, et al. C, estational sac diameter in very early pregnancy as a predictor of fetal outcome[J]. Ultrasound Ohstet Gyneeol, 2002,20(3) :267-269. 被引量：1
3Duguff L, Persutte WH, Schultz LK, et al. Crown-rump length to yolk sac diameter ratio :A new method to predict fetal aneuploidy[J] .Am J Obatet Gynecol, 1998,178(1s) : 143s. 被引量：1
4Brizot ML,Carvalno MH, Liao AW, et al. First-trimester screening for chronmsomal abnormalities by fetal nuchal translucency in Bfizilian population[J]. Ultrasound Obstet Gynecol,2001,18(6) :652-655. 被引量：1
5Cicero S,Curcio P, Papageorghiou A, et al. Absence of nasal bone in fetuses with trisomy 21 at 11-14 weeks of gestation : an observation study[J]. Lancert,2001,358(9294) : 1665-1667. 被引量：1
6Otano L, Aiello H, Igarzabal L, et al. Association between first trimester absence of fetal nasal bone on ultrasound and Down's syndrome[J].Prenat Diagn,2002,22(10) :930-932. 被引量：1
7Orlandi F,Bilardo CM, Campogrande M, et al. Measurement of nasal bone length at 11-14 weeks of pregnancy and its potential role in Down's syndrome risk asssesment[J]. Ultrasound Obetet Gynecol, 2003,23.(6) :496-500. 被引量：1
8Zoppi MA, Ibba RM, Axinan C, et al. Absence of fetal nasal bone and aneuploidies at first trimester nuchal translucency screening in 5425 unselected pregnancies[J]. Prenat Diagn, 2003,22 ( 1 ) : 36-39. 被引量：1
9Ginsberg NA, Storm C, Vedinsky Y. Croton-rump lengths in missed miscarriages and trisomy 21 [J]. Ultrasound Obstet Gyneeol, 2001,18(5) : 488-490. 被引量：1
10Haddow JE, Palomaki GE, Knight GJ, et al. Screening of maternal serum for fetal Down's syndrome in the first trimester[J] .N Engl J Med,1998,338 (14) : 955-961. 被引量：1
二级参考文献19
1Kubas C. Noninvasive means of identifying fetuses with possible Down syndrome: a review. J Perinat Neonatal Nurs, 1999,13:27-46. 被引量：1
2Locatelli A, Piccoli MG, Vergani P, et al. Critical appraisal of the use of nuchal fold thickness measurements for the prediction of Down syndrome. Am J Obstet Gynecol, 2000,182:192-197. 被引量：1
3Hafner E, Schuchter K, Liebhart E, et al. Results of routine fetal nuchal translucency measurement at weeks 10-13 in 4233 unselected pregnant women. Prenat Diagn, 1998,18:29-34. 被引量：1
4Thilaganathan B, Olawaiye A, Sairam S, et al. Isolated fetal echogenic intracardiac foci or golf balls: is karyotyping for Down's syndrome indicated? Br J Obstet Gynecol, 1999,106:1294-1297. 被引量：1
5Simpson J. The cardiac echogenic focus. Prenat Diagn,1999,19:972-975. 被引量：1
6Farina A, Sekizawa A, Ralston SJ, et al. Latent class analysis applied to patterns of fetal sonographic abnormalities: definition of phenotypes associated with aneuploidy. Prenat Diagn, 1999, 19:840-845. 被引量：1
7Roberts D, Walkinshaw SA, McCormack MJ, et al. Prenatal detection of trisomy 21: combined experience of two British hospitals. Prenat Diagn, 2000,20:17-22. 被引量：1
8Grandjean H, Larroque D, Levi S, et al. Detection of chromosomal abnormalities, an outcome of ultrasound screening. The Eurofetus team. Ann NY Acad Sci, 1998,847:136-140. 被引量：1
9Feuchtbaum LB, Currier RJ, Lorey FW, et al. Prenatal ultrasound findings in affected and unaffected pregnancies that are screen-positive for trisomy 18: the california experience. Prenat Diagn, 2000,20:293-299. 被引量：1
10Shields LE, Carpenter LA, Smith KM, et al. Ultrasonographic diagnosis of trisomy 18: is it practical in the early second trimester? J Ultrasound Med,1998,17:327-331. 被引量：1
