A genetic ultrasound can be performed at 16-18 weeks.
Although not as detailed as the 20 week ultrasound, it can help in early identification of major birth defects.
A genetic ultrasound is usually performed if a birth defect is suspected at the first trimester ultrasound, or if there is a specific indication such as a history of a prior birth affected by a birth defect or if any of the genetic screening tests are abnormal.
