ultrasonography(redirected from A-mode ultrasonography)
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The basic principle of ultrasonography is the same as that of depth-sounding in oceanographic studies of the ocean floor. The ultrasonic waves are confined to a narrow beam that may be transmitted through or refracted, absorbed, or reflected by the medium toward which they are directed, depending on the nature of the surface they strike.
In diagnostic ultrasonography the ultrasonic waves are produced by electrically stimulating a crystal called a transducer. As the beam strikes an interface or boundary between tissues of varying density (e.g., muscle and blood) some of the sound waves are reflected back to the transducer as echoes. The echoes are then converted into electrical impulses that are displayed on an oscilloscope, presenting a “picture” of the tissues under examination.
Ultrasonography can be utilized in examination of the heart (echocardiography), in location of aneurysms of the aorta and other abnormalities of the major blood vessels, and in identifying size and structural changes in organs in the abdominopelvic cavity. It is, therefore, of value in identifying and distinguishing cancers and benign cysts. The technique also may be used to evaluate tumors and foreign bodies of the eye, and to demonstrate retinal detachment. Ultrasonography is not, however, of much value in examination of the lungs because ultrasound waves do not pass through structures that contain air.
A particularly important use of ultrasonography is in the field of obstetrics and gynecology, where ionizing radiation is to be avoided whenever possible. The technique can evaluate fetal size and maturity and fetal and placental position. It is a fast, relatively safe, and reliable technique for diagnosing multiple pregnancies. Uterine tumors and other pelvic masses, including abscesses, can be identified by ultrasonography.
See also: ultrasound.
ultrasonographyUltrasound Imaging The generation of diagnostic images–sonograms–based on differences in the acoustic impedance of tissues. See Aortic ultrasonography–US, Breast US, Carotid US, Doppler US, Duplex Doppler US, Endoscopic US, Hydrocolonic US, HIFU, Ocular US, Pancreatic US, Pelvic US, Prostate US, Transcranial US Obstetrics A noninvasive technique for visualizing the gestational sac or fetus in utero.
See also: ultrasound
Synonym(s): echography, sonography.
ultrasonography(ul?tra-so-nog'ra-fe) [ ultra- + sonography]
arterial duplex ultrasonography
endobronchial ultrasonographyAbbreviation: EBUS
pelvic ultrasonographyTransvaginal ultrasonography.
three-dimensional ultrasonography, three-dimensional ultrasound, 3D ultrasonography, 3D ultrasound
transrectal ultrasonography of the prostate
It may be used to diagnose ectopic pregnancy, determine multiple pregnancies, locate the placenta, identify ovarian cysts and pelvic cancers, and visualize tubo-ovarian abscesses. The patient prepares for the ultrasound by removing her clothing from the waist down and dressing in a clean gown. She is helped into a supine position on an examination table, and her knees are placed in approx. 90° of flexion with her feet supported in stirrups. The ultrasound transducer is covered with a condom or sterile glove coated with a lubricant gel. The patient is told that the probe will be inserted into her vagina, and that the gel may feel cold and slippery. The probe is then directed toward the internal organs, from which sound wave (echo) images are obtained, usually painlessly and without ionizing radiation exposure.
ultrasonographyThe use of ultrasonic waves to image body structures for diagnostic purposes. See ULTRASOUND SCANNING.
Synonym(s): echography, sonography.
Patient discussion about ultrasonography
Q. Do doctors normally do ultrasounds to prove you have mis carried?? 2 weeks ago i found out i was pregnant, i started spottion so we went to the hospital where they toldl me i miscarried, but they did not do any alternative tests to prove it not even check my Hcg levels. Im wandering if i should get a second opinion to make sure.
Q. what does it mean when an ultrasound shows an empty amniotic sac and no baby?
Her doctor said it is very common for a woman to have more than one egg fertilize but that in most cases the pregnancy continues as a singleton only. She told my friend that the empty sacs would just disappear through time (which they did) and that they posed no danger to her baby.
Q. what kind of uses the medicine do with computers related to ultra sound? how does the computer helps the doctors in the ultra sound? what do the compuers use for?
for pregnancy purposes, it really helps patient in antenatal screening to find some abnormalities (if there's any) and to monitor the fetus' development along the 9-months pregnancy.
yesterday I wrote a short article about ultrasound update : http://doctoradhi.com/blog/?p=388