✔ 最佳答案
Dr will spend around 20-30min to check carefully every organ of the bb if it's normal or
not.
this test can be taken at around 20 wk (before 24wk)
and cost is around $1000-$1500 in private dr.
It is not a must, and some abnormal can also be found in routine check-up u/s. but still, it's more detailed.
but if you have your routine check-up in public system.. and only 1-2 u/s during the whole 40wks, then this scan can give you more information that missed during routine checkup.