(HealthDay News) -- An obstetric ultrasound is a scan that uses high-frequency sound waves to show an image of a fetus inside the uterus.

It is often requested by obstetricians at intervals throughout a pregnancy to check on the fetus's health.

According to the Radiological Society of North America, an ultrasound may be used to confirm:

• The presence and age of an embryo/fetus.
• Any congenital abnormalities.
• The location and position of the fetus and placenta.
• Multiple pregnancies.
• The amount of amniotic fluid that surrounds the fetus.
• Any abnormalities in the cervix or womb.