Ultrasound must hold urine when examining some abdominal and pelvic tissues and organs. However, not all ultrasounds require urine holding. Especially when the route of ultrasound is through the abdomen, there are some organs that must be held in urine. For example, color ultrasound in the renal pelvis, renal calyces and ureteral stones or tumors, it is necessary to drink water in advance, so that the bladder is moderately full, especially some stones or tumors show unclear and the patient’s subcutaneous fat layer is thicker; bladder disease through the abdominal examination is also necessary to hold urine, because only after the bladder is completely filled in order to identify the bladder wall and the bladder cavity there is no abnormality, especially some of the inflammation of the bladder and bladder cavity, but not all the organs need to hold urine. Especially some bladder inflammation and bladder tumors; and in the transabdominal examination of the uterine adnexa is also required to hold urine one hour in advance. This is mainly to avoid the influence of gas in the intestines, and in addition, the bladder can be used as a translucent window to show the uterus and its adnexal area more clearly, and when there is an abnormality, it can also be shown more clearly. Of course, when there are prostate and seminal vesicle gland examinations, the bladder also needs to be moderately filled. Therefore, in the transabdominal ultrasound examination of the above organs, it is generally necessary to drink 500 to 1000ml of water one hour before the examination to hold urine after the examination.