Abstract
Objective
To assess the efficacy of prenasal thickness (PNT) and nasal bone (NB) for prediction
of Down syndrome (DS) fetuses in the second trimester ultrasound examination.
Study design
PNT was measured from stored two-dimensional fetal profile images taken at 15–23 weeks
in 242 fetuses with normal karyotype (Group 1) and 24 fetuses with DS (Group 2). It
was measured as the shortest distance from the anterior edge of the lowest part of
the frontal bone to the skin. The efficacy of PNT, NB, PNT/NB and biparietal diameter
(BPD)/NB was evaluated for prediction of DS.
Results
PNT values increased with gestational age in normal fetuses. PNT measurement was ≥95th
percentile in 54.2% (13/24) of the DS cases and 2.9% of the normal cases. Receiver
operator curve analysis showed that PNT/NB ratio had the best area under the curve
with a detection rate of 80% for a false positive rate of 5% at a cut-off value of
0.76.
Conclusions
PNT is increased in fetuses with DS as compared to normal fetuses. PNT/NB ≥0.76 in
the second trimester is a better predictor of DS than the use of PNT or NB alone.
Keywords
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Article info
Publication history
Published online: September 09, 2013
Accepted:
August 23,
2013
Received in revised form:
July 31,
2013
Received:
April 24,
2013
Identification
Copyright
© 2013 Elsevier Ireland Ltd. Published by Elsevier Inc. All rights reserved.
