The first trimester ultrasound is performed between the eleventh and thirteenth weeks of amenorrhea. It can precisely date the beginning of pregnancy
and predicts the date of delivery. It is thus primarily a dating ultrasound. Due to its precision, this ultrasound is also morphological. It can verify the proper implantation of the egg in the uterine cavity, measure the size of the embryo and verify its proper development. The first trimester ultrasound helps to detect a multiple pregnancy and to discover possible anomalies.