There are two types of ultrasound commonly used in obstetrics and gynecology: the first, transabdominal ultrasound. It is not necessary to remove pants, but only need to expose the abdomen, in the state of full bladder, that is, in the state of holding urine after the movement of the abdominal probe, and find the uterus fallopian tube ovary whether there is a lesion, morphologically normal or not. The second type, transvaginal ultrasound. You do not need to hold your urine, you need to empty your bladder before you can operate. But you need to take off your pants, expose the vulva, and put the probe into the vagina to perform the ultrasound, which is called a vaginal ultrasound. It is necessary for the diagnosis of early pregnancy, the exclusion of ectopic pregnancy, and the examination of obese women.