Fetal ultrasound is a test used during pregnancy that creates an image of the fetus in the mother’s uterus, or womb. During a fetal ultrasound, various parts of the baby, such as the heart, head, and spine, are identified and measured. The testing may be performed either through the mother’s abdomen (transabdominal) or vaginal canal (transvaginal). Fetal ultrasound provides a safe way to evaluate the health of an unborn baby.

There are several types of fetal ultrasound, each with specific advantages in certain situations. A Doppler ultrasound, for example, helps to study the movement of blood through the umbilical cord between the fetus and placenta. Three-dimensional ultrasound provides a life-like image of an unborn baby. The standard, 2-dimensional ultrasound is the primary focus of this discussion, but the basic concepts for standard fetal ultrasound also apply to the other types.