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How Do Ultrasound Examinations Work?

Jan. 26, 2024



Ultrasound, that is, ultrasonic wave, is a mechanical wave. The frequency of sound waves that our human ears can hear is 20~20000Hz. When the vibration frequency of sound waves is greater than 20,000Hz or less than 20Hz, our ears cannot hear these sounds. Therefore, we call sound waves with frequencies higher than 20,000 Hz ultrasonic waves.

Ultrasound has the characteristics of good directionality, strong penetrating ability, easy to obtain relatively concentrated sound energy, and long propagation distance in water. It can be used for ranging, speed measurement, cleaning, welding, gravel, etc., in medicine, military, industry, agriculture, etc. has a wide range of applications.

The frequency of ultrasound usually used in medical diagnosis is 2~20MHz, which can propagate in the human body and reflect part of it back after hitting different tissues. Based on this physical property, scientists have developed various ultrasound instruments. Ultrasound waves are generated and emitted by the probe. After entering the human body, part of the ultrasonic waves are reflected back according to the differences in the acoustic properties of the organs and tissues. They are then received by the probe and processed by the computer to be displayed and traced in the form of waveforms, curves, and images. The diagnostic method used by ultrasound doctors to judge physiological and pathological conditions based on the characteristics of images is ultrasound examination.


Types of diagnostic ultrasound

There are many types of ultrasound diagnosis, which can generally be divided into type A, type B, type D, type M, etc. At present, the ultrasound diagnosis we commonly use is generally a combination of multiple types, which is what everyone often calls "B-ultrasound".


D-type ultrasound is also called Doppler type. The Doppler frequency-shifted signals of blood flow and organ activity are processed by autocorrelation technology and then color-coded and superimposed on the two-dimensional image of B-mode ultrasound. This is the general meaning. Color Doppler ultrasound. Many people think that color ultrasound is just like a TV, and all the images they see should be full-screen color. In fact, color ultrasound is not full-screen color. Only when observing blood flow signals, it will partially display red or blue. Therefore, color ultrasound can provide both morphological information of two-dimensional images and hemodynamic information, and is the mainstream of ultrasound diagnosis today.


Let’s take a look at the four-dimensional color Doppler ultrasound, which has become very popular in recent years and is very popular among pregnant mothers. Four-dimensional color ultrasound is based on three-dimensional color ultrasound imaging and adds the time dimension, so it can display dynamic three-dimensional images, breaking through the limitations of traditional ultrasound, providing rich imaging information for clinical diagnosis, and reducing missed diagnosis of diseases. Especially in fetal ultrasound examination, it can dynamically display the fetal facial features, limbs and organ development, and enable early diagnosis of fetal congenital developmental abnormalities. In addition, four-dimensional color Doppler ultrasound is becoming more and more widely used in contrast-enhanced ultrasound technology, and the technology is becoming increasingly mature.


Ultrasound medicine is increasingly used in clinical applications and its role is becoming more and more important. With the adoption and improvement of new ultrasound technologies, it is continuously integrated and developed with clinical practice and is inseparable. It plays a great role in the diagnosis and treatment of diseases. It plays an increasingly important role in the medical service system.


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Trolley Color Doppler Ultrasound


Trolley B/W Ultrasound


Portable Color Doppler Ultrasound 


Portable B/W Ultrasound


Portable Veterinary Ultrasound


Wireless Ultrasound



Technical Characteristics of Ultrasound Diagnosis


There is no pain, no trauma, and no radiation for the subject. The method is simple, the examination is rapid and effective, the image is clear, real-time dynamics, the diagnostic accuracy is gradually improved, it is widely used, and the examination charges are low, etc., making ultrasonic diagnosis widely used in hospitals of all levels and hospitals. It has been widely used in individual clinics.


Ultrasound diagnosis, X-ray CT, nuclear magnetic resonance, and isotope examination technologies go hand in hand and develop very rapidly. Each has its own advantages in clinical diagnosis and is irreplaceable and complementary to each other. It not only greatly improves the level of clinical medical diagnosis and treatment, but also solves the diagnosis problems of various difficult diseases and makes great contributions to human health.


Application scope of ultrasound diagnosis


(1)Routine ultrasound examinations of the upper abdomen (liver, gallbladder, pancreas, spleen), urinary system (kidneys, ureters, bladder, prostate), gynecology (uterus, appendages), etc.;


(2)Ultrasound examination of various superficial organs and body surface masses (eyes, thyroid, parotid gland, submandibular gland, breast, scrotum, etc.);


(3)Adult and infant fetal heart ultrasound examination;


(4)Vascular ultrasound examination (arterial and venous blood vessels in the neck, arterial and venous blood vessels in the upper and lower limbs, abdominal blood vessels and some superficial blood vessels, etc.);


(5)Ultrasound examination of various joints and muscles and bones;


(6)Various puncture, positioning, fluid extraction, catheterization and treatment procedures under ultrasound guidance;


(7) Various health examination items.


Precautions for ultrasound diagnosis


(1)The upper abdomen (liver, gallbladder, and pancreas) needs to be examined on an empty stomach in order to reduce the interference of gastrointestinal contents and gas. If there is a barium meal, gastroscopy, or colonoscopy on the same day, an ultrasound examination should generally be arranged first;


(2)For women to check the uterus and appendages, and for men to check the bladder, prostate and seminal vesicles, it is necessary to fill the bladder appropriately before doing the examination;


(3)For transvaginal ultrasound examination, the bladder needs to be emptied before the examination. However, those with excessive menstrual period and vaginal bleeding and unmarried women should not undergo vaginal ultrasound examination.


(4)Pregnant women within 3 months of pregnancy need to hold their urine moderately for examination. After 3 months of pregnancy, there is generally no need to hold urine. When placenta previa is suspected, it is necessary to hold urine to further understand the situation of the placenta and the internal cervical os. No other special preparations are required, just fully expose the area being inspected during the inspection.


(5)Revisiters should bring past medical records or other examination reports so that doctors can make systematic and comprehensive comparisons and diagnoses.


(6)During the examination, please wait in line in order and keep quiet. Special patients such as the elderly, the weak, the disabled, the young, and those with severe emergencies can be examined first after discussing with others. Please obey the arrangement.


(7)Depending on the conditions of each hospital, appointments for fetal system ultrasound, four-dimensional ultrasound, fetal heart ultrasound and interventional ultrasound generally need to be made in advance.


(8)Any examination has certain limitations. The examination results are mainly systematically identified and diagnosed by clinicians. Ultrasonic diagnosis cannot replace clinical diagnosis.

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