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(A-Z listing includes diseases, conditions, tests and procedures)


What is an ultrasound?

An ultrasound is a noninvasive diagnostic procedure that produces images, which are used to assess soft tissue structures, including muscles, blood vessels, the heart and various organs.

Ultrasound uses a transducer that sends out an ultrasound wave at a frequency too high to be heard. The ultrasound transducer is placed on the skin, and the ultrasound waves move through the body to the organs and structures within. The sound waves bounce off the organs like an echo and return to the transducer. The transducer processes the reflected waves, which are then converted by a computer into an image of the organs or tissues being examined. 

The sound waves travel at different speeds depending on the type of tissue encountered — fastest through bone tissue and slowest through air. The speed at which the sound waves are returned to the transducer, as well as how much of the sound wave returns, is translated by the transducer as different types of Tissue.

An ultrasound gel is placed on the transducer and the skin to allow for smooth movement of the transducer over the skin and to eliminate air between the skin and the transducer for the best sound conduction.

Another type of ultrasound is Doppler ultrasound, sometimes called a duplex study, used to evaluate the speed and direction of blood flow in arteries and veins, and blood flow to an organ. Unlike a standard ultrasound, some sound waves during the Doppler exam are audible.

Illustration of a  transabdominal ultrasound procedure
Click Image to Enlarge

Ultrasound procedures are used to examine many different parts of the body, including the liver, kidneys, gall bladder, pancreas, breasts, female pelvis, prostate, scrotum, thyroid, heart and the vascular system. During pregnancy, ultrasounds are performed to evaluate the development and growth of the fetus.

Ultrasound is also used to guide various types of biopsies and invasive procedures, including thyroid biopsies, liver biopsies, prostate biopsies, kidney transplants and amniocentesis.

Technological advancements in the field of ultrasound now include images that can be made in a three-dimensional view (3-D) and/or four-dimensional (4-D) view. A 4-D is a 3-D view that also shows movement.

What are the different types of ultrasound procedures?

Examples of some of the more common types of ultrasound examinations:

  • Doppler or vascular ultrasound: used to evaluate blood flow in a vessel. Doppler ultrasound can determine if there are any blood clots or blockages in the arteries or veins.

  • Echocardiogram: used to see the heart and its valves to evaluate the effectiveness of the heart's pumping ability and to check whether the valves are leaking

  • Abdominal ultrasound: used to detect any abnormalities of the abdominal organs (i.e., kidneys, liver, pancreas, gallbladder), such as gallstones or tumors

  • Renal ultrasound: used to examine the kidneys and urinary tractObstetrical ultrasound. Used to monitor the development of the fetus

  • Obstetrical ultrasound: used to monitor the development of a fetus

  • Pelvic ultrasound: used to find the cause of pelvic pain or evaluate masses felt on a pelvic exam

  • Breast ultrasound: used to examine a mass in the breast tissue

  • Thyroid ultrasound: used to detect any abnormalities or nodules felt in the thyroid or neck

  • Scrotal ultrasound: used to further investigate pain in the testicles or masses or swelling detected on a physical exam

  • Prostate ultrasound: used to examine any nodules felt during a physical examination and to guide for a prostate biopsy

  • Musculoskeletal ultrasound: used to examine joints or muscles to evaluate for causes of pain, such as a tear
  • Endoscopic ultrasound: performed in conjunction with an endoscopic procedure and used to evaluate masses of the esophagus, stomach and pancreas

  • Intraoperative ultrasound: used to help the surgeon during a minimally invasive operation or biopsy

  • Interventional ultrasound: used by an interventional radiologist to guide a minimally invasive procedure

  • Intravascular ultrasound: used to provide direct visualization and measurement of the inside of blood vessels

How are ultrasounds performed?

An ultrasound procedure may be done as an outpatient basis or as part of inpatient care. Although each facility may have different protocols in place, generally an ultrasound procedure follows this process:

  1. Ultrasound gel is placed on the area of the body that will undergo the ultrasound examination.

  2. Using a transducer, a device that sends out the ultrasound waves, the ultrasound wave will be sent through the patient's body.

  3. The sound will be reflected off structures inside the body, and the ultrasound machine will analyze the information from the sound waves.

  4. The ultrasound machine will create an image of these structures on a monitor. These images will be stored digitally.

  5. There are no confirmed adverse biological effects on patients or instrument operators caused by exposures to ultrasound at the intensity levels used in diagnostic ultrasound.

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