Here menstruation going back 20 years means 20 years of menopause. After 20 years of menopause, vaginal blood today may be caused by endometrial cancer, cervical cancer, senile vaginitis, ovarian functional tumor and other reasons. 1. Endometrial cancer: it may cause vaginal bleeding again after menopause, usually in small amount, accompanied by foul-smelling vaginal bleeding or plasma discharge, lower abdominal pain, etc. The combination of clinical manifestations, ultrasonography, diagnostic curettage and hysteroscopy may assist in the diagnosis. 2. Cervical cancer: it may cause vaginal bleeding after 20 years of menopause, accompanied by vaginal discharge with fishy odor, which can be diagnosed by cervical cytology, colposcopy and cervical biopsy. 3. Geriatric vaginitis: After menopause, the vulva and vaginal mucosa lose the support of estrogen, resulting in thinning of the mucosa and a decrease in resistance, which leads to vaginal bleeding symptoms when pathogens invade. Under the guidance of the doctor, topical estrogen ointment can be used for treatment, and antibiotic treatment, such as levofloxacin and metronidazole, can be given at the same time. 4. Functional ovarian tumors: such as granulosa cell tumor, can cause irregular vaginal bleeding that reappears after menopause, gynecological examination can touch bilateral solid or cystic solid mass, poor mobility, and accompanied by peritoneal fluid, combined with the history, gynecological examination and ultrasonography, serum sex hormone level can assist in the diagnosis. After 20 years of menopause, when there is blood in the vagina today, you need to go to the hospital in order to find out the cause and treat it promptly.