The brown discharge on the fourth day of intercourse could be contact bleeding after intercourse, abnormal uterine bleeding due to endocrine imbalance, or ovulatory bleeding, the specific cause of which should be analyzed on a case-by-case basis. Most of the contact bleeding after intercourse occurs one or two days after intercourse, and the patient can be found to have cervical erosion or cervical polyps during gynecological examination. Abnormal uterine bleeding caused by endocrine disorders depends on when the bleeding occurs, whether it occurs during the proliferative phase of menstruation or the luteal phase, and this treatment is also different. Ovulatory bleeding is closely related to the ovulation period. Generally speaking, the amount of ovulatory bleeding is small and short-lived, disappearing in three or four days. The above three cases of ovulatory bleeding are a normal physiological phenomenon and do not need to be dealt with, while the other two cases should be seen by a hospital for the next step of treatment.