If the endometrium is 23mm, it is not certain that it is cancer. Further examination is needed, which can be done by hysteroscopy to see if there is endometrial hyperplasia or endometrial polyps, or small submucosal fibroids, which cause the endometrium to be 23mm.If you want to determine whether it is benign or malignant, the gold standard is to do pathology, which can be done by scraping the uterus to get the pathology, or by taking the pathology under the hysteroscopy, which is more accurate, and the diagnosis based on the pathology can be the initial judgment of whether it is a Benign or malignant lesions. It is not possible to tell whether the endometrium is cancerous or not simply from the 23mm endometrium, but it is necessary to further examine and take biopsies for pathology, so as to make a clear diagnosis.