Coffee-colored discharge after menstruation is mainly considered to be ovulation bleeding, which is mainly caused by a transient decrease in estrogen during ovulation. Because there is a necessary condition for the patient to have ovulation, which is that the estrogen should reach 200pg/ml and maintain it for 48 hours. After ovulation, estrogen levels will drop briefly, so the endometrium loses the support of high hormone levels and a small amount of exfoliative bleeding occurs, which usually lasts for about 3-4 days. After ovulation, the corpus luteum continues to secrete estrogen and progesterone, so estrogen and progesterone will rise again for a short period of time, and in the process of rising, the endometrium will be repaired and transformed, so that the patient’s bleeding will stop soon, and the amount of bleeding is also very small.