Ultrasound can examine the liver, gallbladder, spleen, pancreas, kidneys, bladder, heart, uterus, ovaries and other organs. The accuracy of ultrasound without holding urine depends on the method of ultrasound. If ultrasound of the urinary system is performed via the abdomen or ultrasound of gynecology is performed, a filled bladder is needed to understand the bladder, ureter, uterus, ovaries, etc. Only by holding urine will the examination be accurate. If ultrasound is performed via the natural cavity, such as through the vagina or through the rectum, the bladder usually needs to be emptied in order to clearly see the uterus and ovaries, and there is no need to hold urine. I. Gynecologic ultrasound: 1. Gynecologic abdominal ultrasound: Gynecologic abdominal ultrasound usually examines the uterus and ovaries. If abdominal ultrasound is performed without holding urine the uterus and ovaries cannot be seen accurately. Under normal circumstances, the uterus and ovaries are located deep in the pelvis and both are solid organs that cannot be seen in the abdomen without the support of the bladder. The uterus and ovaries can only be understood after the bladder is held up and the urine is compared with the uterus and ovaries after the bladder is full. If you do not hold urine or do not have enough urine, you cannot see the uterus and ovaries accurately through abdominal ultrasound. 2. Ultrasound through the natural cavity: vaginal ultrasound as well as rectal ultrasound can directly observe the uterus and ovaries, which removes the disadvantage of having to hold urine to do abdominal ultrasound, and patients who choose this test can do so without holding urine. Other: For ultrasound examination of the bladder and ureter, the bladder should be kept full in order to fully observe any lesions in the bladder and ureter, so it is necessary to hold urine.