One day, when I was out of the specialist clinic, I saw a few special patients. One little patient, just 5 years old, was lively and cute, but her father, who brought her here, had gray hair and looked anxious. It turns out that the father, a year ago, took the little girl back home to Jiangxi to play for a summer. After returning, the mother found that the little girl’s underwear repeatedly had yellow discharge, the city, the provincial hospital, including children’s hospitals ran a number of external washing, internal anti-inflammatory drugs used a lot, but also ineffective. The girl’s mother was very angry and worried, and kept complaining to her husband that he should not have taken the child back to the countryside where the hygiene conditions were not good, so that the child had an unknown disease. The child’s father, because of self-blame and anxiety, took the child to seek medical treatment, and in less than a year, his hair turned gray. Another patient, a 20-year-old unmarried woman, began to have menstrual periods for more than 10 days six months ago, and the ultrasound repeatedly showed no abnormalities. It was not until she came to the clinic that her period lasted for 20 days. The third patient, a young woman, had been married for more than 3 years, but she was still unable to have children after seeking medical help. I listened patiently to their stories, went through their past medical records, and performed the necessary tests for them, and concluded that they should all undergo hysteroscopy, which is similar to gastroscopy and colonoscopy and is the best means of diagnosing diseases of the vagina, uterus and other natural cavities of the body. Currently, the slimmest hysteroscope is only 2.1 mm in diameter, which is equivalent to the thickness of a cotton swab. Under anesthesia, it is gently inserted into the vagina and uterus of a woman and the lesions can be seen very clearly. Young girls and women who have not had sex can also have the cause of the lesion clarified quickly without damaging the hymen. All three patients, who agreed to the doctor’s recommendation, underwent hysteroscopy. The doctors found an 8mm diameter plastic button in the girl’s vagina through the hysteroscope. The vaginal mucosa around the button was already congested and inflamed, so the doctors carefully removed the button and thoroughly flushed the girl’s vagina with disinfectant. The girl was in no pain and was discharged the next day with her relieved father. As for the unmarried girl, the doctor found a peanut-sized polyp in her uterine cavity with a hysteroscope in the outpatient clinic and removed it at the same time. She went home the same day. After the operation, her menstruation was very normal every month. The third infertile woman, the doctor performed a hysteroscopy and unblocking of her fallopian tubes in the clinic the day after her menstruation. Endometritis was the cause of her long-term infertility. After two months of anti-inflammatory treatment, she got pregnant naturally. Now, her daughter is 3 years old. Hysteroscopy has now become another minimally invasive technology for gynecological diagnosis and treatment after hysterosalpingography, ultrasound and other means of examination. It has been developed for more than 100 years and has been introduced to China for more than 30 years. It has become quite mature. If ultrasound and other methods are used to look through the abdominal wall and uterine wall to determine the condition, hysteroscopy is used to look at the lesion through the natural cavity of the body without any incision. It is said that hysteroscopy is like a doctor’s third eye, which extends the doctor’s line of sight and makes diagnosis more intuitive and accurate. Postmenopausal vaginal bleeding, infertility, sterility, recurrent spontaneous abortion, abnormal vaginal bleeding at any age (including young and old women), unexplained increase in vaginal discharge; excessive menstruation, hypomenorrhea, secondary amenorrhea, malformation of uterine development, postpartum placenta residue, failure to clear the uterus after incomplete abortion, difficulty in removing the birth control ring, etc., can be diagnosed and treated by hysteroscopy. Moreover, hysteroscopic treatment of uterine septum, uterine adhesions, submucosal fibroids and endometrial polyps is currently recognized as the most minimally invasive and irreplaceable method in the academic gynecological field.