An ultrasound test is a radiology technique, which uses high- frequency sound waves to produce images of the organs and structures of the body. The sound waves are sent through body tissues with a device called a transducer. The transducer is placed directly on top of the skin, which has a gel applied to the surface. The sound waves that are sent by the transducer through the body are then reflected by internal structures as “echoes.” These echoes return to the transducer and are transmitted electrically onto a viewing monitor. The echo images are then recorded on a plane film and can also be recorded on videotape. After the ultrasound, the gel is easily wiped off.
The technical term for ultrasound testing and recording is “sonography.” Ultrasound testing is painless and harmless. Ultrasound tests involve no radiation and studies have not revealed any adverse effects.
For what purposes are ultrasounds performed?
Ultrasound examinations can be used in various areas of the body for a variety of purposes. These purposes include examination of the chest, abdomen, blood vessels (such as to detect blood clots in leg veins) and the evaluation of pregnancy. In the chest, ultrasound can be used to obtain detailed images of the size and function of the heart. Ultrasound can detect abnormalities of the heart valves, such as mitral valve prolapse, aortic stenosis, and infection (endocarditis). Ultrasound is commonly used to guide fluid withdrawal (aspiration) from the chest, lungs, or around the heart. Ultrasound is also commonly used to examine internal structures of the abdomen. Gallstones in the gallbladder are easily detected, as are kidney stones. The size and structure of the kidneys, the ureters, liver, spleen, pancreas, and aorta within the abdomen can be examined. Ultrasound can detect fluid, cysts, tumors or abscess in the abdomen or liver. Impaired blood flow from clots or arteriosclerosis in the legs can be detected by ultrasound. Aneurysms of the aorta can also be seen. Ultrasound is also commonly used to evaluate the structure of the thyroid gland in the neck.
During pregnancy, an ultrasound can be used to evaluate the size, gender, movement, and position of the growing baby. The baby’s heart is usually visible early, and as the baby ages, body motion becomes more apparent. The baby can often be visualized by the mother during the ultrasound, and the gender of the baby is sometimes detectable.
How do patients prepare for an ultrasound?
Preparation for ultrasound is minimal. Generally, if internal organs such as the gallbladder are to be examined, patients are requested to avoid eating and drinking with the exception of water for six to eight hours prior to the examination. This is because food causes gallbladder contraction, minimizing the size, which would be visible during the ultrasound. In preparation for examination of the baby and womb during pregnancy, it is recommended that mothers drink at least four to six glasses of water approximately one to two hours prior to the examination for the purpose of filling the bladder. The extra fluid in the bladder moves air-filled bowel loops away from the womb so that the baby and womb are more visible during the ultrasound test.
How are results transmitted to the patient and doctor?
The ultrasound is generally performed by a technician. The technician will notice preliminary structures and may point out several of these structures during the examination. The official reading of the ultrasound is given by a radiologist, a physician who is an expert at interpreting ultrasound images. The radiologist records the interpretation and transmits it to the practitioner requesting the test. Occasionally, during the ultrasound test the radiologist will ask questions of the patient and/or perform an examination in order to further define the purpose for which the test is ordered or to clarify preliminary findings. Plain x-rays might be ordered to further evaluate early findings. A summary of results of all of the above is reported to the practitioner who requested the ultrasound. They then are discussed with the patient in the context of overall health status.