Menstruation coming back 15 days after removing the IUD may be due to menopausal menstrual disorders, luteal insufficiency, ovulation bleeding, uterine fibroids or endometrial polyps, and so on. 1. Menopausal menstrual disorders: If women in menopause experience this situation, it is considered to be menopausal menstrual disorders. Hormonal fluctuations in the body will change during menopause, which will cause menstrual disorders, but it should be consulted in time to rule out abnormalities. 2. Luteal insufficiency: If the level of estrogen or progesterone in the body is insufficient, it will lead to premature luteal phase decline, poor endometrial secretion response and shortening of the luteal phase, which can also be manifested as frequent menstruation. 3. Ovulation bleeding: IUD removal is usually carried out after the end of menstruation, and when it takes about 15 days after IUD removal, it is mostly in the ovulation period. During the ovulation period, due to the one-off decline of hormone level in the body, which is unable to support the uterine lining, a small amount of endometrial lining will fall off, and some people may think that it is the menstruation coming again. 4. Uterine fibroids or endometrial polyps: Uterine fibroids and endometrial polyps may cause abnormal bleeding from the uterus and may also be the cause of bleeding during menstruation. There may be other reasons why your period came back 15 days after removing the IUD, so we recommend that you go to the hospital for a detailed examination to rule out any abnormalities, and then treat the cause of the problem.