Doppler is an ultrasound examination based on black and white ultrasound plus color Doppler, which can not only provide two-dimensional ultrasound structural images of organs, but also provide hemodynamic information, and is widely used in the examination of vascular diseases, abdominal diseases and gynecological diseases. 1. Vascular diseases: It can be used for the examination of heart diseases, such as congenital heart disease, rheumatic heart disease, coronary atherosclerotic heart disease, etc., which can assess the structure of the heart, blood vessels and valve function; it can also be used for the examination of blood vessels of the limbs, such as arterial phlebitis and arterial embolism of the lower limbs, etc.; it can be used for cerebral vascular examination, which can assess the blood supply to the brain and vascular obstruction to the important cerebral vessels, through the examination of cerebral hemodynamics and parameters of the blood flow. Through the examination of cerebral hemodynamics and blood flow parameters, it can assess the blood supply to the brain and the effect of vascular obstruction on the blood flow of important vessels in the brain. 2. Abdominal conditions: It can identify the benign or malignant nature of occupying lesions in the abdomen, such as liver, spleen, pancreas, gallbladder, kidney, ureter, bladder, etc. It has a good preliminary diagnosis of cirrhosis of the liver, hepatic cysts, hepatic hemangiomas, hepatocellular carcinoma, renal stones, hydronephrosis, and prostate enlargement, etc. It can also be used for the examination of gynecological diseases. 3. Gynecological diseases: It has good diagnostic effect on common gynecological diseases such as uterine fibroids, uterine cysts, endometrial polyps, ectopic pregnancy, etc. In addition, it can also be used for screening of the fetal system, which greatly improves the detection rate of malformed fetuses. It should be noted that the Doppler abdominal examination should be performed on an empty stomach, and urinary and gynecological examinations should be performed on a urine-holding basis, as prescribed by the doctor. There is no need to panic when the test results are abnormal, and it is important not to self-diagnose on the basis of a single test, which should be analyzed according to the specific situation under the guidance of the doctor.