Hi !! Usually scans are performed at 8 weeks,10-14 weeks ,18 to 24 weeks,32-33 weeks.if you want the tiffa scan it's already late.anywsys late tiffa can be done.if you want growth scan you need to wait for 4 more weeks. Normal scan is enough for growth and amniotic fluid assessment. Only if there is a specific reason colour doppler is recommended.

USG growth scan + Doppler (since it catches early iugr) Dr Dyuti Navadia MBBS DNB (obstetrics and Gynaecology)