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Fetal nasal bone and trisomy 21 in the second trimester
Author(s) -
Viora E.,
Errante G.,
Sciarrone A.,
Bastonero S.,
Masturzo B.,
Martiny G.,
Campogrande M.
Publication year - 2005
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/pd.848
Subject(s) - trisomy , nasal bone , medicine , fetus , obstetrics , aneuploidy , second trimester , gynecology , pregnancy , biology , anatomy , genetics , chromosome , gene
Objectives To assess the feasibility of measuring nasal bone length in the second trimester of pregnancy and to confirm if fetal nasal bone absence or hypoplasia is a marker for Down syndrome. Methods Fetal nasal bone assessment was performed in 439 consecutive singleton pregnancies at high risk of Down syndrome between 15 and 21 weeks. All ultrasound examinations were performed transabdominally by five skilled sonographers. If the nasal bone was present, its length was measured. The biparietal diameter: nasal bone length ratio (BPD/NBL) was also calculated. Results Nasal bone assessment was successfully achieved in all fetuses. The nasal bone was absent in 2(0.47%) of the 417 unaffected fetuses and in 10(55.5%) of the 18 fetuses with trisomy 21. Of the 8 Down syndrome cases with a nasal bone present, 4 had nasal bone hypoplasia and 4 had a normal nasal bone. BPD/NBL was 9 or greater in 7 of the 8 fetuses affected by trisomy 21 with nasal bone present and in 86 (20.6%) of the 417 normal fetuses; it was 10 or greater in 5 of the 8 (62.5%) fetuses affected by trisomy 21 and in 41 of the 417 (9.8%) euploid fetuses. Conclusions Nasal bone absence is a marker for Down syndrome in the second trimester of pregnancy. Inclusion of nasal bone length into the second‐trimester screening protocol could potentially obviate the false‐negative cases from other screening tests. The measurement of nasal bone length in the second trimester seems to provide additional benefits beyond the assessment of the presence or absence of the nasal bone. Copyright © 2005 John Wiley & Sons, Ltd.