Atrophic Vaginitis: This condition is the most common cause of vaginal bleeding in postmenopausal women. The decrease in estrogen levels leads to thinning and drying of the vaginal walls, making them more susceptible to bleeding.

Endometrial Hyperplasia or Cancer: These conditions are more common in postmenopausal women and can cause irregular vaginal bleeding. Risk factors include unopposed estrogen therapy, obesity, and family history of endometrial cancer.
Uterine Fibroids: Although more common in premenopausal women, fibroids can still cause bleeding in the elderly, especially if they are large or undergo degeneration.
Cervical Polyps or Cancer: Cervical lesions can cause postmenopausal bleeding and should be considered in the differential diagnosis.

Endometrial Cancer: Although listed as an "other likely diagnosis," it's crucial to emphasize that missing a diagnosis of endometrial cancer can have severe consequences. It's essential to investigate any postmenopausal bleeding thoroughly.
Uterine Sarcoma: A rare but aggressive tumor that can cause vaginal bleeding. Early detection is critical for treatment.
Ovarian Cancer: Although less directly related to vaginal bleeding, ovarian cancer can cause irregular bleeding in some cases, especially if there is metastasis to the uterus or vagina.

Vaginal Cancer: A rare type of cancer that can cause bleeding, especially if the tumor is large or ulcerated.
Metastatic Cancer to the Vagina or Uterus: Cancers from other primary sites (e.g., colon, breast) can metastasize to the female genital tract, causing bleeding.
Arteriovenous Malformations: Rare vascular anomalies that can cause vaginal bleeding, often requiring specialized imaging for diagnosis.