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1.The nuchal thickness is measured on an axial section through the head and the level of the thalami, cavum septi pellucidum and cerebellar hemispheres (i.e in the same plane that is used to assess posterior fossa structures). One caliper should be placed at the skin, and the other against the outer edge of the bone of the occiput.
2.An abnormal value is one that is more than 6 mm in thickness.
3.A thick nuchal fold is often considered the most sensitive and most specific (best) 2nd trimester marker for Down syndrome with false positive rates as low as 1%.
4.But one thing you have to remember that
ultrasound is operator dependent - so possibilities of technical error can be there.
5.So please wait or a doctor to scan after a week or as soon as you can get appointment. Hope the best. Good luck.
Hope i have answered your query.
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