51 years old menstruation stopped for 1 year and came back if it is caused by menopausal syndrome, it is normal, if it is caused by endometrial polyps, ovarian cancer, as well as other diseases such as cervical cancer, it is not normal. 1. Menopause syndrome: 51-year-old women enter menopause after ovarian function will gradually fail, the patient’s body sex hormones will decline significantly. Patients will have menstrual disorders, hot flashes, excessive sweating, pain during sexual intercourse and other manifestations, so the 51-year-old woman appeared to menstruation stopped for a year and then came back due to menopausal syndrome, is a normal phenomenon. 2. Endometrial polyps: the cause of endometrial polyps is not yet clear, mostly considered to be caused by high estrogen levels and foreign bodies in the uterine cavity. Patients will manifest as postmenopausal vaginal bleeding, bleeding between menstrual periods, heavy menstrual flow, vaginal discharge of foul-smelling bloody secretions. Therefore, it is not a normal phenomenon that a 51-year-old woman with endometrial polyp will have the symptom of menstruation coming back after 1 year of menopause. 3. Ovarian cancer: the cause of ovarian cancer is not yet obvious, and it is mostly considered to be related to endometriosis, hormonal changes in the body and other factors. Patients may manifest postmenopausal bleeding, irregular vaginal bleeding and lower abdominal pain. If the 51-year-old woman’s appearance of menstruation stopping for 1 year and coming back is caused by ovarian cancer, it is not a normal manifestation. 4. Other: 51-year-old women whose menstruation has stopped for 1 year and come back again is caused by cervical cancer, cervical polyp, endometrial cancer, etc., which is mostly not a normal phenomenon. Therefore, 51-year-old women appear menstruation stopped for 1 year and come back to menstruation is caused by menopause, mostly considered a normal performance. If it is caused by ovarian cancer or cervical cancer, it is not a normal phenomenon.