Transrectal ultrasound is not usually associated with pain, but with perianal discomfort, which is mostly mild. Transrectal ultrasound involves placing a probe into the rectum, and the test should ideally be performed after a bowel movement. If the patient has not yet defecated, an enema is needed to remove the stool from the intestines. First, it can check the rectum or perianal diseases, such as rectal polyps, rectal tumor size and level of invasion. It can also check the location and size of perianal abscesses, as well as the internal opening of anal fistulae and the alignment of sinus tracts, etc. Secondly, it can be used to examine gynecological diseases, such as pelvis, uterus and adnexa, bladder, ureter, and prostate of men.