After diagnostic scraping surgery, after taking medication, large chunks of blood are discharged for about 20 days, which may be caused by the influence of medication, endometrial cancer and uterine fibroids. 1. The influence of drugs: diagnostic scraping, i.e. diagnostic scraping, is a common method to diagnose uterine cavity diseases, which should be operated by professional physicians and the scraped tissues should be sent to pathological examination. When a lot of vaginal bleeding occurs about 20 days after diagnostic scraping and drug treatment as prescribed by doctor, it may be due to drug withdrawal bleeding after stopping the drug, which will usually recover gradually. 2. Endometrial cancer: it can also cause profuse vaginal bleeding about 20 days after diagnostic scraping, accompanied by bleeding or plasma discharge from the vagina, which can be diagnosed with the help of history, clinical manifestations, ultrasonography and pathological findings of diagnostic scraping. 3. Uterine fibroids: they can also cause increased menstrual flow, and can also lead to prolonged menstrual period, which can be diagnosed with the assistance of gynecological examination and ultrasonography. After diagnostic scraping surgery, when there are large clots of blood discharged, it is necessary to go to the hospital in time to find out the cause and actively deal with it.