Anal ultrasound is performed with the lubricant above the probe inserted into the anus, which can help determine perianal lesions. In addition, patients need to keep their intestines clean before having an anal ultrasound. The body in the anus B ultrasound examination, need to use a condom in the probe above, and then in the probe on top of the lubricant inserted into the anus, and then from the outside to the inside rotating probe, this time the monitor can be observed to the rectum, which can help to diagnose whether there is a perianal lesion, such as fissure, fistula, anal polyps, hemorrhoids, anal papillomas and so on. It is recommended that patients need to use soapy water enema before anal ultrasound examination, or drink sodium phosphate oral solution, 33% magnesium sulfate solution to clean the intestines under the guidance of the doctor. It is recommended that patients can go to regular hospitals for anal ultrasound; in addition, patients need to eat light and easy to digest food, such as rice porridge, noodles, etc., before anal ultrasound examination, follow the doctor’s instructions to do intestinal preparation, etc., the specific precautions related to the specific can also consult the doctor.