title: Comparison of nuchal and detailed morphology ultrasound examinations in early pregnancy for fetal structural abnormality screening: a randomized controlled trial.
abstract: OBJECTIVE
  To compare the effectiveness of a nuchal scan at 10 to 14 + 6 weeks and a detailed morphology scan at 12 to 14 + 6 weeks in screening for fetal structural abnormalities.
  
  
  METHODS
  From March 2001 to November 2004, 8811 pregnant women were randomized into either the control group (10 to 14 + 6-week nuchal scan followed by routine 16-23-week scan) or the study group (10 to 14 + 6-week nuchal scan and 12 to 14 + 6-week detailed scan followed by routine 16-23-week scan).
  
  
  RESULTS
  We analyzed 7642 cases of singleton pregnancies with viable fetuses at first-trimester ultrasound examination and with known pregnancy outcome. In the control group, the detection rate of structural abnormalities in the first trimester was 32.8% (21/64; 95% CI, 21.6-45.7%) and the overall detection rate was 64.1% (41/64; 95% CI, 51.1-75.7%). In the study group, the detection rate in the first trimester was 47.6% (30/63; 95% CI, 34.9-60.6) and the overall detection rate was 66.7% (42/63; 95% CI, 53.7-78.0%). The overall detection rate in the control group did not differ significantly from that in the study group (P > 0.05).
  
  
  CONCLUSIONS
  When the nuchal scan is offered, a basic anatomical survey can be done in conjunction with nuchal translucency thickness measurement. A detailed ultrasound examination at this early gestational age may not be superior to the nuchal scan in screening for fetal abnormalities in the low-risk population. Though a wide range of abnormalities can be detected at 10 to 14 + 6 weeks, the routine 16-23-week scan cannot be abandoned.
authors.affiliation: Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China. drchenmin2003@yahoo.com.hk
authors.forename: M
authors.initials: M
authors.lastname: Chen
authors.forename: C P
authors.initials: CP
authors.lastname: Lee
authors.forename: Y H
authors.initials: YH
authors.lastname: Lam
authors.forename: R Y K
authors.initials: RY
authors.lastname: Tang
authors.forename: B C P
authors.initials: BC
authors.lastname: Chan
authors.forename: S F
authors.initials: SF
authors.lastname: Wong
authors.forename: L H Y
authors.initials: LH
authors.lastname: Tse
authors.forename: M H Y
authors.initials: MH
authors.lastname: Tang
mesh_terms: D000328:Adult; D004314:Down Syndrome / Q000000981:diagnostic imaging; D005260:Female; D005333:Fetus / Q000002:abnormalities*; D006801:Humans; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D016216:Ultrasonography, Prenatal