An ultrasound is a procedure that uses high frequency sound waves, called ultrasonic waves, to produce images of internal organs and the interior of the body. This form of imaging works largely in the same way as sonar. Ultrasound images are often used in obstetrics but have non-obstetric uses including biopsies and echocardiographs. They can be used to produce either a still or moving image.
Sound waves traveling through different objects is integral to producing an ultrasound image. An ultrasonic sensor called the transducer targets the organ or area of the body being scanned, emitting ultrasonic waves. An echo is produced when the sound waves hit different tissue. The transducer detects the echo and feeds the data into a computer. The computer will then transform the sound into images.
In order for the transducer to easily move over the skin, a gel is applied. This gel also helps to allow the transducer as close to the skin as possible. A slight pressure may be felt if the area is tender due to inflammation. The transducer may also be inserted into the body for an exam. Mild anesthesia is often used for internal exams.
There are no limitations to activity after the ultrasound. The image produced from an ultrasound is interpreted by a trained professional or radiologist who may then give the patient his or her results. Often, results are passed along to the patient's general practitioner.
Ultrasounds do not have any side effects, as radiation is not used. It is a relatively easy and low cost procedure. These also produce real time images and can be used to help guide invasive procedures. The main concern with ultrasound is that it does not easily distinguish between air and bone and not good for imaging bones or the lungs.
An ultrasound is commonly used to produce a sonogram or picture of a baby in the uterus. The image may be used to determine the size of the baby, reveal multiple babies, identify some abnormalities and diseases, and is necessary for amniocentesis. Other conditions that can be detected using an ultrasound include early fetal death, an impending miscarriage, and placenta position. This procedure is used after a woman is 16 weeks pregnant.
Other non-obstetric uses of ultrasounds are used to examine internal organs. Tumors, swelling and cysts can all be examined using these high frequency waves. An echocardiograph is a special type of ultrasound used to investigate the heart. This is a diagnostic procedure that looks at structural abnormalities and blood flow through valves.
Most ultrasound examinations are painless, fast and easy.
After you are positioned on the examination table, the radiologist or sonographer will apply some warm water-based gel on your skin and then place the transducer firmly against your body, moving it back and forth over the area of interest until the desired images are captured. There is usually no discomfort from pressure as the transducer is pressed against the area being examined.
If scanning is performed over an area of tenderness, you may feel pressure or minor pain from the transducer.
Ultrasound exams in which the transducer is inserted into an opening of the body may produce minimal discomfort.
If a Doppler ultrasound study is performed, you may actually hear pulse-like sounds that change in pitch as the blood flow is monitored and measured.
Once the imaging is complete, the gel will be wiped off your skin.
After an ultrasound examination, you should be able to resume your normal activities immediately.
A radiologist, a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a signed report to your primary care physician or the physician who referred you for the exam, who will share the results with you. In some cases the radiologist may discuss results with you at the conclusion of your examination.
Follow-up examinations are often necessary, and your doctor will explain the exact reason why another exam is requested. Sometimes a follow-up exam is done because a suspicious or questionable finding needs clarification with additional views or a special imaging technique. A follow-up examination may be necessary so that any change in a known abnormality can be detected over time. Follow-up examinations are sometimes the best way to see if treatment is working or if an abnormality is stable over time.
Most ultrasound scanning is noninvasive (no needles or injections) and is usually painless.
Ultrasound is widely available, easy-to-use and less expensive than other imaging methods.
Ultrasound imaging does not use any ionizing radiation.
Ultrasound scanning gives a clear picture of soft tissues that do not show up well on x-ray images.
Ultrasound is the preferred imaging modality for the diagnosis and monitoring of pregnant women and their unborn babies.
Ultrasound provides real-time imaging, making it a good tool for guiding minimally invasive procedures such as needle biopsies and needle aspiration.
For standard diagnostic ultrasound there are no known harmful effects on humans.
Ultrasound waves are disrupted by air or gas; therefore ultrasound is not an ideal imaging technique for air-filled bowel or organs obscured by the bowel. In most cases, barium exams, CT scanning, and MRI are the methods of choice in this setting.
Large patients are more difficult to image by ultrasound because greater amounts of tissue attenuates (weakens) the sound waves as they pass deeper into the body.
Ultrasound has difficulty penetrating bone and, therefore, can only see the outer surface of bony structures and not what lies within (except in infants). For visualizing internal structure of bones or certain joints, other imaging modalities such as MRI are typically used.