The blood is coffee-colored, and the menstrual period is long. What is the reason?

Patient's question:

Menstrual period is long, the color is coffee-colored

Doctor's answer:

Hello, there are many reasons that can cause excessive menstrual bleeding. It may be due to endocrine disorders, or it may be caused by systemic and local factors. Common causes include uterine fibroids, especially submucosal uterine fibroids. Even small-sized fibroids can cause excessive menstrual bleeding. The next are adenomyosis and pelvic endometriosis. Due to factors such as the growth of the endometrium into the uterine muscle wall and the enlargement of the uterus, the amount of menstrual blood is often relatively large.