Ultrasound examination has become one of the preferred clinical examination methods.
1.Is ultrasound examination harmful to human body?
A: Ultrasound is a high frequency sound wave, it is not radioactive, safe and harmless to human body, widely used in the whole body organs and systems as well as prenatal examination of the fetus, it is also very safe for pregnant women. Ultrasound examination has become one of the preferred clinical examination methods.
2.Do all ultrasound examinations require fasting?
A: Not all ultrasound examinations require fasting. Fasting is only required for abdominal organs, such as liver, gallbladder, pancreas, spleen, kidney, abdominal vessels, lymph nodes, etc. and gastrointestinal ultrasound examinations for more than 8 hours to reduce the interference of celiac disease and gas in the gastrointestinal tract and to improve the imaging quality.
For patients with frequent abdominal distension, it is recommended to take a light diet and appropriate amount of digestive drugs the night before the examination before performing ultrasound examination. In addition, the contraction of the gallbladder becomes smaller after eating, which makes it difficult to distinguish whether the gallbladder is physiological or pathological, and also affects the display of lesions in the gallbladder cavity.
3.Why should I fast when performing abdominal ultrasound examination?
This is because, unlike other imaging imaging, gas interference is the primary natural enemy of ultrasound. The inherent acoustic properties of ultrasound lead to an increase in gas in the gastrointestinal tract, which will increase the reflection of ultrasound and obviously affect the image quality, which is especially obvious in abdominal ultrasound examination.
Since diagnostic ultrasonography has high resolution for tissue structures, ultrasound is difficult to penetrate and almost totally reflected at interfaces with high contrast such as solid-gas or liquid-gas. If after eating, some gas can be swallowed with food, which increases intestinal gas, and some other foods, such as soy products themselves, can easily produce gas.
If the gastrointestinal contents increase, the above organs will be pushed to different degrees, and the edges of certain organs are not easily displayed will have information missed.
and the gastrointestinal contents block the penetration of most of the ultrasound, so that the organs behind them are poorly displayed or partially not displayed.
Gas interference will make the retroperitoneal vessels and both renal arteries more difficult to display, especially the gas with intestinal peristalsis and movement will also produce color artifacts, making it difficult to clearly display the blood flow signal.
Many patients often delay the examination due to inadequate preparation before the examination.
Usually, the upper abdominal organs that need to be examined on an empty stomach include the liver, gallbladder, bile ducts, pancreas, adrenal glands, renal arteries, left renal vein, abdominal vessels, retroperitoneum and upper abdominal masses.
Because the gallbladder is full when fasting, the ultrasound image is easy to display and can truly reflect the maximum volume and shape of the gallbladder of the person being examined. If the test is still unclear at this time, it is necessary to perform another low-fat vegetarian diet for three days and then come back on an empty stomach for comparison and judgment. In addition, some people should not do ultrasound immediately after barium X-ray of the gastrointestinal tract because the barium can prevent the penetration of ultrasound.
Properly prepare for fasting examination, should do, the night before the examination, the subject should eat a light diet, avoid fatty foods, it is advisable to eat a light diet, can eat less meat, eggs, beans and other gas-producing foods the day before the examination, appropriate to eat some green vegetables or food with laxative and exhausting effect (such as green radish), ensure sufficient sleep, and empty the bowels, early in the morning fasting waiting for the examination, so that a more satisfactory image can be obtained.
4.Why do some ultrasound examinations require holding urine first? To what extent is it appropriate to hold it?
A: Before performing urinary system examinations such as bladder, ureter, prostate, etc., as well as gynecological ultrasound examinations for unmarried women, patients with more vaginal bleeding and those in the first trimester of pregnancy, it is necessary to hold urine to fill the bladder moderately in order to reduce intestinal gas interference and provide a good transmission window. In addition, pregnant women in their third trimester or less should have a properly filled bladder.
Doing gynecologic ultrasound requires a bladder volume of 300-400 ml of urine. As far as experience is concerned, drinking 500 ml-800 ml of water before the examination usually requires holding urine for 2 hours, and drinking 800 ml-1000 ml of water requires holding urine for about 1 hour. The sign of a well-filled bladder is a shallow arc of lower abdominal bulge when lying down, and the ability to press down and hold it when adding pressure.
5.What is the fluid applied to the examination area during the examination? Is it harmful to human body?
A: The liquid is coupling agent, the purpose is to make good contact between the probe and the skin, conducive to the transmission of sound waves and improve the quality of imaging.
Coupling agent is a water-soluble liquid, non-toxic, harmless to humans, wipe clean or wash with warm water after the examination.