Sherya any diagnostic centre will do but I suggest you to go for the best one. They will measure the fluid retention behind the baby's neck and the measurement will be perfect if good sonologist do it. Can suggest you if you are in Navi mumbai where I saw.

hi... NT scan is a normal scanning which is done in fist trimester to find out the probability of having abnormalities n down syndrome in baby.... u cn visit any diagnostic centre like del or suburban fr d test... thus test has two parts fist is scan n other is double mrker test... combining the results of both these, d doctor will tell u ur probablity... don worry... i too had it yesterday only n blood test reports r still awaited...