How does an ultrasound work? What can it see?
An ultrasound machine uses high-frequency sound waves to create an image of the baby in the womb. The machine sends sound waves through the abdomen and into the uterus. The waves bounce off the baby and are reflected back to the machine. A computer creates a picture of the baby from these reflections. Ultrasounds can usually see everything except the baby's bones, which appear as black shadows on the screen.
