Dysfunctional Uterine Bleeding (DUB): This is the most common cause of prolonged vaginal bleeding, especially in women of reproductive age. It is often related to hormonal imbalances, particularly anovulatory cycles, leading to irregular and prolonged bleeding.

Uterine Fibroids: These are common benign tumors that can cause prolonged and heavy vaginal bleeding due to their location and effect on the uterine lining.
Endometrial Hyperplasia: A condition where the lining of the uterus grows too thick, which can lead to prolonged and irregular bleeding. It's more common in perimenopausal women.
Intrauterine Device (IUD) Complications: Certain types of IUDs, especially those that are non-hormonal, can cause prolonged vaginal bleeding as a side effect.
Thyroid Disorders: Both hypothyroidism and hyperthyroidism can affect menstrual regularity and lead to prolonged bleeding.

Endometrial Cancer: Although less common, endometrial cancer can present with prolonged vaginal bleeding and must be ruled out, especially in postmenopausal women or those with risk factors.
Cervical Cancer: Can also present with abnormal vaginal bleeding, including prolonged bleeding, and is critical to diagnose early.
Pregnancy-Related Complications: Ectopic pregnancy or a molar pregnancy can cause abnormal and prolonged vaginal bleeding.
Coagulopathy: Bleeding disorders such as von Willebrand disease can lead to prolonged vaginal bleeding and must not be overlooked.

Uterine Arteriovenous Malformation (AVM): A rare condition that can cause significant and prolonged vaginal bleeding due to abnormal blood vessel formation in the uterus.
Uterine Sarcoma: A rare type of cancer that can present with abnormal uterine bleeding.
Genetic Bleeding Disorders: Other than von Willebrand disease, conditions like factor XI deficiency can also lead to prolonged bleeding, though they are less common.