Ultrasonography is the full name of ultrasonic imaging examination, which mainly clarifies whether the structure and function of the examined area are normal or not. Usually, ultrasonography can be categorized into four major types according to the location: cardiac ultrasound, abdominal ultrasound, vascular ultrasound and superficial ultrasound.1. Cardiac ultrasound: it can clarify whether the structure and function of the heart are normal. Usually, it can observe whether the size of each atrial chamber of the heart, valves are normal, whether there is valve regurgitation, valve stenosis, abnormal systolic and diastolic function of the heart, etc., or whether there are abnormal manifestations in the atria and chambers of the heart, such as abnormal pathways or abnormal thrombus, etc.; 2. Abdominal ultrasound: it can be used for the examination of the liver, gallbladder, pancreas, spleen, kidneys and other substantial organs, and to clarify the existence of pathological conditions. At the same time, the ureter, bladder and other cavity organs are also examined synchronously, and ascites, pelvic fluid and changes in abdominal blood vessels can be monitored. It can also be used for obstetrics and gynecology examination, such as uterine ultrasound, adnexal ultrasound, vaginal ultrasound, etc., to clarify whether there is any abnormality in the uterus, adnexa and other organs, and also to clarify whether there is any pregnancy and the specific situation of the fetus in the uterus. 3. Vascular ultrasound can also be used to detect the presence of thrombus or plaque formation; 4. Ultrasound of other parts: some small organs can also be subjected to ultrasound, such as the eyes, which can be used to observe the presence of vitreous dislocation. Thyroid ultrasound can be used to observe whether there are nodules in the thyroid gland. Breast ultrasound can clearly show all layers of soft tissues of the breast and the morphology of the masses therein, the internal structure and the changes of adjacent tissues.