Uterine fibroids: Noncancerous growths in the uterus that can cause heavy bleeding. Endometrial polyps: Growths in the lining of the uterus that can lead to prolonged bleeding. Adenomyosis: A condition where the inner lining of the uterus breaks through the muscle wall of the uterus. Pelvic inflammatory disease (PID): Infections in the reproductive organs can cause irregular bleeding. Bleeding disorders: Conditions such as von Willebrand disease can result in extended menstrual bleeding.
