Comparison of nuchal and detailed morphology ultrasound examinations in early pregnancy for fetal structural abnormality screening: a randomized controlled trial.
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.
Chen
M
M
Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China. drchenmin2003@yahoo.com.hk
Lee
C P
CP
Lam
Y H
YH
Tang
R Y K
RY
Chan
B C P
BC
Wong
S F
SF
Tse
L H Y
LH
Tang
M H Y
MH
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