Atrophic Vaginitis: This condition is the most common cause of postmenopausal bleeding, resulting from the thinning and drying of the vaginal walls due to decreased estrogen levels. It is characterized by symptoms such as vaginal dryness, itching, and pain, in addition to bleeding.

Endometrial Hyperplasia: This condition involves the thickening of the lining of the uterus (endometrium) and can be caused by an imbalance of estrogen and progesterone. It is a common cause of postmenopausal bleeding and can be a precursor to endometrial cancer.
Endometrial Polyps: These are growths in the lining of the uterus that can cause bleeding. They are more common in postmenopausal women and can be benign or, less commonly, cancerous.
Hormone Replacement Therapy (HRT): Women on HRT may experience postmenopausal bleeding due to the hormonal effects on the endometrium.

Endometrial Cancer: Although less common than other causes, endometrial cancer is a critical diagnosis not to miss due to its potential for serious morbidity and mortality. Risk factors include obesity, diabetes, and unopposed estrogen exposure.
Cervical Cancer: While less common than endometrial cancer, cervical cancer can also present with postmenopausal bleeding and must be ruled out, especially in women with a history of abnormal Pap smears or those not up to date with cervical cancer screening.

Uterine Sarcoma: A rare type of cancer that originates in the muscle and supporting tissues of the uterine walls. It can cause postmenopausal bleeding among other symptoms.
Ovarian Cancer: Although primarily presenting with abdominal symptoms, ovarian cancer can occasionally cause postmenopausal bleeding, especially if it involves the uterus or vagina.
Vaginal Cancer: A rare type of cancer that can cause bleeding, especially if it involves the upper part of the vagina.