If you find that your underwear is brown in color the day after intercourse, this is because there was bleeding at the time of intercourse. The bleeding is not discharged from the vagina in time, and it accumulates in the vagina and turns brown when it is discharged from the vagina. Contact bleeding is commonly associated with cervical inflammation, vaginal inflammation, cervical cancer, and submucosal fibroids that have a tip, which can also cause bleeding during intercourse. Therefore, it is recommended to have a gynecological examination to understand the local condition of the vulva, vagina and cervix. If there are superfluous organisms, it is recommended to remove them for pathological examination, and it is also recommended to do cervical cancer screening to understand whether there are cancerous or precancerous lesions in the cervix, which need to be treated promptly in clinical practice. In case of submucosal fibroids, hysteroscopy is recommended to remove the submucosal fibroids.