Before going to the ultrasound the patient is expected to fast for at least 8-12 hours, as the undigested food in the stomach obstructs the sound waves and forms difficulty in acquiring the precise images from the procedure.  However, there is an exemption to fasting if the patient is having an ultrasound of their liver, gallbladder, pancreas, and spleen.

The whole procedure of ultrasound is done within 30 minutes. Prior to the ultrasound, the patient is said to change into a hospital gown and remove any kind of accessories that can impede the images of the scan. The different kinds of ultrasound scans are performed in a different ways. In external ultrasound, the probe is moved over the skin of the patient after applying a lubricating gel to remove any air pockets between the instrument and the skin. In an internal ultrasound scan, the probe is inserted inside the body of the patient with a sterile cover, which is not much broader than a finger is then gently passed into the vagina or rectum, thus this kind of ultrasound is also called a transvaginal ultrasound. In an endoscopic ultrasound scan, the probe is attached to a long, thin, flexible tube and passed farther into the body.