At the age of fifty-one, menstruation stopped for a year and came back again, considering that it is related to ovarian hypoplasia, endometrial polyps, uterine fibroids, cervical lesions, and malignant lesions of the endometrium, and so on. 1. Ovarian hypoplasia: As women age, ovarian function gradually decreases, and the level of estrogen and progesterone in the body decreases, which in turn causes women to experience irregular vaginal bleeding. 2. Endometrial polyps: For patients with endometrial polyps, it is mostly due to the lack of progesterone in the body that causes the endometrium to continue to be affected by the action of estrogen and hyperplasia of benign lesions, and the patients mostly take irregular vaginal bleeding as the main manifestation. 3. Uterine fibroids: for patients with uterine fibroids, due to the increase in uterine volume and surface area of the endometrium, it may lead to the reappearance of vaginal bleeding after menopause. 4. Cervical lesions: if the cervical tissue is combined with human papillomavirus infection, it will develop into pre-cancerous cervical lesions and cervical cancer, and the patients mostly take contact bleeding as the main manifestation. 5. Endometrial malignant lesions: for patients with endometrial cancer, due to the rapid growth of cancer cells, persistent vaginal bleeding and weight loss may occur after invading local blood vessels. For women who are 51 years old and their menstruation has stopped for a year and come back again, it is recommended that they go to the gynecology department of regular hospitals to improve ultrasound, cervical cancer screening and other related examinations, and then take active treatment under the guidance of doctors after the cause of the disease is clarified.