An endometrium of 15mm may be a normal physiological condition or there may be a problem of endometrial thickening that may be harmful. Sometimes there are underlying diseases, such as endometrial polyps, endometrial hyperplasia, or even endometrial cancer. If the test is in the luteal phase of the second half of the menstrual cycle, before the onset of menstruation, or in the early stages of pregnancy, it is normal and usually not harmful. In addition, if the endometrium is 15mm, there are clinical cases where pregnancy is detected by examination. However, because of the short period of pregnancy, no gestational sac can be seen through ultrasound examination. This is also normal and it is recommended to review ultrasound examination at intervals to determine whether it is intrauterine pregnancy. If it is in the first half of the follicular phase of the menstrual cycle, i.e. after menstruation, it is endometrial thickening. If it is after menopause, an endometrial thickness of 15 mm is also considered endometrial thickening, which is dangerous and hazardous. If endometrial thickening is clearly diagnosed, generally choose hysteroscopy plus treatment. Common causes and hazards are as follows: 1. Endometrial polyp: It can cause abnormal vaginal bleeding, abnormal leucorrhea and other symptoms, and some patients may also have infection, glandular hyperplasia and malignancy. To perform endometrial polyp removal, send pathology testing to clarify the diagnosis, because in rare cases endometrial polyps do have the possibility of malignant transformation. In addition to the examination of endometrial polyps, a thorough curettage is usually performed before the end of the hysteroscopy, and the uterine cavity is scraped out and sent for pathological testing to clarify whether there is an endometrial lesion and to determine the next step based on the pathological test results. If the pathology test is normal there is no need for any treatment, just follow up and observe. 2. Endometrial hyperplasia: It can lead to irregular vaginal bleeding from the uterus, often accompanied by weakness, palpitations, dizziness, etc., heavy bleeding, and even shock and anemia. If the pathology test suggests a simple hyperplasia, progestin therapy in the second half of the menstrual cycle is usually the treatment of choice. If the pathology results suggest complex hyperplasia, progestin therapy is usually given for the full menstrual cycle. If the pathology suggests atypical hyperplasia, total hysterectomy is indicated in most cases. If you insist on preserving the reproductive function, you can also try high-dose progestin therapy first, and then perform hysterectomy after completing the reproductive function. 3. Endometrial cancer: Patients will have symptoms such as irregular vaginal bleeding, vaginal discharge, abdominal pain, abdominal mass, etc. Advanced patients may have anemia, emaciation, and cachexia, and those with distant metastasis will have symptoms in the corresponding area. If the pathological test results suggest that it is already endometrial cancer, the standard treatment for endometrial cancer should be given. It usually includes total hysterectomy, double adnexal resection, plus lymph node dissection, and the decision of whether to supplement radiotherapy or chemotherapy after surgery should be based on whether there are high-risk recurrence factors.