Ultrasound is like radar that uses sound waves to look inside the body. It does not hurt and warm gel is used on the skin to help the transducer move more smoothly and make better contact.
Most ultrasound studies do not need any preparation. There are a few exceptions:
When the test is scheduled, you will be told for how long the child cannot eat before the study or will be told how much to drink beforehand. The amount will depend on the child's age.
Preparing for an ultrasound