There are numerous cause leading to heavy periods before menopause. It could be due to Fibroids or extra growth of muscles of the uterus (adenomyosis) or due to chocolate cyst ovary where blood accumulates in ovaries. At times the inner lining of the uterus becomes thick leading to heavy bleeding. Need not worry. They can all be treated by micro surgery or laparoscopic surgery now a days. Only 1-2 days hospital stay.