An ultrasound examination, also called sonography or sonogram, is an imaging method that uses high-frequency sound waves to produce images of organs and structures within your body. The images produced during this exam often provide information that is valuable in diagnosing and treating a variety of diseases and conditions.
Most ultrasound examinations are performed using a transducer or probe on the skin surface, but sometimes an ultrasound examination requires the use of an internal transducer or probe.
Even though ultrasound examinations provide valuable information, ultrasound can not provide images of all areas of your body, but there are several other imaging alternatives which can provide that information.
Why Ultrasound Is Performed
Your physician may order an ultrasound for a variety of reasons. Ultrasound may be used, among other things, to evaluate the following:
- Thyroid gland
- Scrotum and contents
- Female reproductive organs (e.g. cervix, uterus, ovaries, etc.)
- Pyloric stenosis
- Pediatric heads
- Blood vessels (e.g. aorta, IVC, renal arteries, portal system, arteries of arms and legs, neck, Allen’s test, etc.)
- DVT (veins in legs & arms)
- Muscle and tendons
- Soft tissue
In addition, ultrasound can also be used for guidance in the following interventional procedures to help determine types of cancers, diseases and infections:
- Biopsy (e.g. liver, thyroid, breast, kidney, lymph nodes, etc.)
- Aspirations (e.g. thyroid nodules or cysts, lymph nodes, breast cysts, etc.)
- Thoracentesis (drainage of pleural fluid from chest cavity)
- Paracentesis (drainage of abdominal fluid from abdominal cavity)
- Vascular access (e.g. PICC lines, central lines, etc.)
- Drainages (i.e. abscesses, fluid collections, etc.)
Risks of Ultrasound
Diagnostic ultrasound is a safe procedure that uses low-power sound waves. There are no direct risks from a diagnostic ultrasound exam; however, sometimes higher power sound waves can be used for treatment purposes to heat and even destroy some types of tissue or tumors.
Although ultrasound is a valuable tool, it does have its limitations. Sound does not travel well through air or bone, so ultrasound is not effective at imaging parts of the body that have gas in them or that are obscured by bone. Rather than using ultrasound to view these areas, your physician may instead order other imaging tests, such as CT, MRI or X-Ray.
How to Prepare for Your Exam
How you prepare for an ultrasound exam depends on which area of your body needs evaluation. Some exams require no preparation, some require no food or fluids for up to 8 hours before the exam, while others require a full bladder. When scheduling your ultrasound exam, ask your physician for specific instructions for your particular exam.
What to Expect
During an ultrasound exam, you usually lie on an examination table and gel is applied to your skin. The gel helps eliminate the formation of air pockets between the ultrasound probe and your body. During the exam, a trained technician (sonographer) presses a small handheld device (transducer) against your skin over the area of your body being examined, moving from one area to another as necessary.
Based on the same principles as sonar, a technology used to detect underwater objects, the transducer generates and receives high-frequency sound waves that can not be heard by the human ear.
As the sonographer places the transducer on your skin, crystals inside the transducer emit pulses of sound waves that travel into your body. Your tissues, bones and body fluids reflect the sound waves and bounce them back to the transducer. The transducer then sends this information to a computer, which composes detailed images based on the patterns created by the sound waves.
Though the majority of ultrasound exams are performed with a transducer on your skin, some ultrasounds are done inside your body (invasive ultrasounds). For these exams, the probe is inserted into a natural opening in your body.
Transvaginal Ultrasound: A small, specialized transducer is inserted into a woman’s vaginal canal to view uterus and ovaries, as well as for early pregnancies.
Ultrasound is usually a painless procedure; however, you may experience some mild discomfort as the Sonographer guides the transducer over your body, especially if you’re required to have a full bladder. A typical ultrasound exam usually takes from 30 minutes to an hour.
When your exam is complete, the radiologist analyzes the images and sends a report of the findings to your physician. If your ultrasound exam is for an urgent medical condition, your physician should receive your results immediately. Otherwise, you should have your results within a few days.