Why do color Doppler ultrasound have to hold urine

Ultrasound, as a common means of examination, is easy to operate, safe to use and widely used. It is the preferred method for screening and follow-up of many diseases. Whether it is necessary to hold urine depends on the part to be examined. If blood vessel color Doppler ultrasound, cardiac color Doppler ultrasound, hepatobiliary, pancreatic, spleen and kidney color Doppler ultrasound, thyroid color Doppler ultrasound, etc. are performed, these color Doppler ultrasound do not need to hold urine. If bladder color Doppler ultrasound is performed, it is necessary to hold urine. This is because the bladder is empty when there is no urine. It is impossible to observe whether there are stones, tumors and other space-occupying lesions in the bladder. only after holding urine and the bladder is in a filling state can the lesions in the bladder be observed. In addition, if men do prostate and women do ultrasound of uterine appendages, they also need to hold urine, because the uterus and prostate are deep in the pelvis. If the bladder is not filled up, the images of these organs will be unclear, which may cause misdiagnosis and missed diagnosis. Therefore, it is necessary to hold urine when doing these examinations. Therefore, whether it is necessary to hold urine for color Doppler ultrasound needs to be determined according to the items examined and the requirements of the doctor.