If the ultrasound examination needs to fill the bladder, you can generally drink 500ml of water before the examination to hold urine, the specific amount of water can be based on the degree of bloating that the individual can tolerate. Bladder capacity is generally around 400ml, due to the time limit of the examination, if you want to quickly accumulate water to the bladder, you can drink 500ml of plain water on top of the appropriate amount of tea or coffee, because drinks containing caffeine have a diuretic effect on the organism, you can also choose watermelon juice, orange juice and other fruit drinks, all of which can help to quickly produce urine. In the process of drinking the above drinks need to pay attention to small sips to facilitate rapid absorption into the circulation of the body. In addition, it is generally necessary to drink about 30 minutes before the examination to avoid improper timing and inability to complete urine holding during the examination time. When the bladder is in a full state and there is no excessive gas in the bladder, the examination is better and a clear diagnosis can also be made. If there is no urine in the bladder, some organs in front of the uterus will block the ultrasound window of the ultrasound probe and affect the examination results, which is not conducive to a clear diagnosis. It should be noted that drinking water should not be too much, so as not to exceed the bladder tolerable range, resulting in failure to hold urine. Patients should be aware that there are some clinical tests that do not require urine holding, such as vaginal ultrasound, where no water is required before the test and urine evacuation is required.