The need to hold urine for routine color Doppler ultrasound examinations depends on the area to be examined, some areas need to hold urine and some do not. For example, ultrasound of the liver, gallbladder, spleen, pancreas, thyroid, breast, and heart, which are often performed in hospitals, do not need to hold urine. However, in the case of pelvic ultrasound, such as bladder ultrasound, prostate ultrasound and seminal vesicle ultrasound in urology, these organs are located in the pelvic cavity, and it is necessary to hold urine in this case. Ultrasound of the uterus and adnexa in gynecology are also ultrasound of the pelvic organs, which also requires holding urine because the bladder is filled with urine and liquid, which can be used as a sign and also enables the next organs to be seen more clearly. If the bladder is completely empty without holding urine, all the organs in the pelvic cavity are gathered together and it is not easy to distinguish the tissue characteristics, so it is necessary to prepare for holding urine when performing pelvic ultrasound routinely.