An ultrasound is a diagnostic tool that uses high-frequency sound waves to construct images of the inside of the body, according to MedlinePlus. The sound waves bounce off of the internal organs and structures. A computer uses those reflected sound waves to create the picture.
Ultrasounds are most often associated with pregnancy, but they are also useful for diagnosing medical conditions and guiding physicians during medical procedures, states WebMD. An example is using the ultrasound to guide the needle during a biopsy.
The patient lies down for the ultrasound while the ultrasound technician uses a handheld transducer to perform the ultrasound, explains MedlinePlus. The transducer emits the sound waves which create the images. The technician uses a clear gel product to transmit the waves and allow the transducer to move across the skin to capture different angles.
In some cases, the technician can't get a clear ultrasound picture from outside the body. Special transducers allow the technician to go inside the body for a closer look, according to WebMD. Transvaginal ultrasounds get a closer look at the uterus and ovaries, while a transrectal ultrasound gets closer to the prostate. Another variation is the transesophageal echocardiogram, where the transducer goes into the esophagus for a closer look at the heart.
Ultrasounds have the advantage of being painless and generally non-invasive, without the radiation associated with X-rays and CT scans. They also work better on soft tissues than other imaging methods such as X-rays.