The diseases involved in hysteroscopy are as follows: 1. irregular vaginal bleeding: if the uneven thickness of the endometrium is detected by ultrasound and the vaginal bleeding is not improved after a period of medication, the first choice is hysteroscopy to clarify the morphology and structure of the uterine cavity and the presence of endometrial lesions; 2. tumors in the vagina and fibroids found during gynecological examination, hysteroscopy is needed to clarify whether there is an occupancy in the uterine cavity and whether the occupancy is benign or malignant to avoid delaying the disease; 3. hysteroscopy is needed for patients with uterine polyps and infertility; 4. menstruation does not occur after curettage or abortion, hysteroscopy is needed to clarify whether the uterine cavity is adhered.