Hormonal Imbalance: This is often the most common cause of abnormal uterine bleeding, particularly in women of reproductive age. Hormonal fluctuations can lead to irregular ovulation, affecting the normal menstrual cycle and resulting in abnormal bleeding patterns.

Uterine Fibroids: These are common benign tumors that can cause heavy or irregular menstrual bleeding due to their location and size affecting uterine lining shedding.
Endometrial Hyperplasia: This condition involves the thickening of the uterine lining, which can lead to abnormal uterine bleeding. It's often associated with hormonal imbalance, particularly excess estrogen.
Polycystic Ovary Syndrome (PCOS): A hormonal disorder causing enlarged ovaries with small cysts on the outer edges, PCOS can lead to irregular periods and abnormal uterine bleeding due to ovulation problems and hormonal imbalance.
Intrauterine Devices (IUDs): Certain types of IUDs, especially those that release hormones, can cause changes in menstrual bleeding patterns, leading to abnormal uterine bleeding.

Endometrial Cancer: Although less common, endometrial cancer is a critical diagnosis not to miss. It can present with abnormal uterine bleeding, especially in postmenopausal women. Early detection is crucial for effective treatment.
Cervical Cancer: Abnormal vaginal bleeding can be a symptom of cervical cancer. Regular screening is essential for early detection.
Pregnancy-Related Complications: Ectopic pregnancy or a miscarriage can cause abnormal uterine bleeding. These conditions require immediate medical attention.
Bleeding Disorders: Conditions like von Willebrand disease can lead to heavy menstrual bleeding and should be considered, especially in young women with significant menstrual bleeding.

Adenomyosis: A condition where tissue similar to the lining inside the uterus grows into the muscular walls of the uterus, leading to heavy or painful periods.
Uterine Arteriovenous Malformations: Rare vascular lesions that can cause abnormal uterine bleeding due to the abnormal connection between arteries and veins.
Thyroid Disorders: Both hyperthyroidism and hypothyroidism can affect menstrual regularity and lead to abnormal uterine bleeding.
Pituitary Tumors: Although rare, tumors of the pituitary gland can disrupt normal hormonal balance, leading to various menstrual irregularities, including abnormal uterine bleeding.