1·Nuchal scan is performed between 11 and 14 weeks of gestation, because the accuracy is best in this period.
颈背扫描完成11至14周的妊娠，因为最好的准确性是在这个时期。
2·A nuchal scan is a sonographic prenatal screening scan (ultrasound) to help identify higher risks of Down syndrome in a fetus, particularly for older women who have higher risks of such pregnancies.
阿颈背扫描是扫描超声产前筛查(超声波)，以帮助确定风险较高的唐氏综合征胎儿中，特别是对老年妇女有较高的风险，谁这样怀孕。