Ultrasound, sometimes referred to as a sonogram can be performed at any time during pregnancy. First trimester ultrasounds are often used to confirm the due date. An ultrasound done between 11 and 13 weeks gestation can be used to screen for early markers associated with chromosomes abnormalities, whereas later ultrasounds can be used to evaluate fetal anatomy. It is important to note that some fetal anomalies can be detected by ultrasound but many cannot. In some cases, serial ultrasounds may be recommended to evaluate interval growth and recheck anatomy.