It is not possible to do colonoscopy during menstruation.1. Due to the stimulation of the endoscope on the intestine when doing colonoscopy causes contraction of the pelvic muscle, resulting in the flow of menstrual blood from the uterus. Since the anus and genitals of women are close to each other, they may contaminate the endoscope and perineal area. Since the operation of colonoscopy is a bacterial operation, the immunity of female reproductive organs is weak at this time, which may easily lead to gynecological inflammation, such as cervicitis, endometritis, etc. 2. Since menstrual blood contaminates the endoscope, it is easily confused with bleeding in the intestine and bleeding from anal diseases, which may be misdiagnosed. 3. Since the uterus is close to the rectum and colon, the endoscope can stimulate the uterus and cervix through the endoscope when doing colonoscopy This can lead to an increase in menstrual flow. Therefore, when doing colonoscopy, try to avoid the menstrual period, should be carried out 3-5 days after menstruation.