Ultrasound scanning is a safe and painless procedure used to look at the organs inside the body. It uses high-frequency sound waves and their echoes to create video pictures of the organs. It is especially useful for soft tissue, such as the kidneys, liver, and uterus. Soft tissue does not show up well on regular X-ray images.
Ultrasound is used to diagnose diseases or conditions. For example, it may be used to look for kidney stones. During pregnancy it can be used to examine an unborn baby, the placenta, the fluid around the baby, and the uterus. For example, it may be used to check the growth of the baby or help confirm the baby’s due date. Ultrasound is also useful for looking at the heart while it works because it can show the opening and closing of the valves. In addition it can show how well the heart is pumping.
In general, you do not need to do anything special to prepare for the scan. Some specific tests, such as an ultrasound of the uterus, require a full bladder. If preparations are necessary, your healthcare provider will give you instructions.
High-frequency sound waves pass through the body from a small device called a transducer placed on your body. A gel or oil is usually put on the skin to improve the contact between your body and the transducer. The transducer is connected to a computer with a display screen. As the sound waves pass through the body, they are reflected by body organs and create echoes. The computer converts these echoes into images of the body organs.
Some ultrasound exams are done with a probe put into the rectum or a woman's vagina. For these scans, the transducer is shaped like a narrow tube and covered with a lubricated condomlike sheath. The probe is inserted gently into the rectum or vagina.
A special ultrasound, called Doppler ultrasound, is used to check movement in organs, for example, blood flowing through blood vessels.
Generally an ultrasound scan takes 15 to 30 minutes to complete.
Usually you can go home and go back to your normal activities as soon as the scan is done. You may be able to have the results within a few minutes to a few days later.
There are no known risks associated with ultrasound scanning because the sound waves used are not dangerous. However, if it is necessary to use anesthesia or to insert a medical instrument into the body to conduct the ultrasound, there may be a slight risk associated with the procedure.
Call your healthcare provider during office hours if: