Objective To update the likelihood ratio for trisomy 21 in fetuses with absent nasal bone at the 11-14-week scan. Methods

Objective To examine the association between absence of the nasal bone at the 11-14-week ultrasound scan and chromosomal defects. NT < 2.5 mm, for NT ≥ 4.5 mm. In the chromosomally abnormal group the nasal bone was absent in 161/242 (66.9%) with trisomy 21, in 48/84 (57.1%) with trisomy 18, in 7/22 (31.8%) Methods

Objective To determine the value of measuring maxillary length at 11-14 weeks of gestation in screening for trisomy 21. Methods