Atrophy of the Vagina or Endometrium: This condition is common in postmenopausal women due to decreased estrogen levels, leading to thinning and drying of the vaginal and endometrial tissues. It can cause intermittent bleeding, pain, and discomfort, especially during sexual activity.

Endometrial Polyps: These are growths in the lining of the uterus that can cause irregular bleeding, including postmenopausal bleeding. They are more common in postmenopausal women and can be associated with hormonal influences.
Uterine Fibroids: Although more common in premenopausal women, fibroids can still cause symptoms in postmenopausal women, especially if they are large or if there is a change in their size. They can lead to bleeding, pelvic pressure, and pain.
Hormone Replacement Therapy (HRT) Side Effects: If the patient is on HRT, it could be contributing to the bleeding, especially if there's an imbalance or inappropriate type of hormone therapy for her specific needs.

Endometrial Cancer: This is a critical diagnosis not to miss, as it can present with postmenopausal bleeding. Risk factors include obesity, hypertension, and unopposed estrogen exposure. Prompt investigation is necessary due to the potential for serious outcomes if left untreated.
Ovarian Cancer: Although less directly linked to postmenopausal bleeding, ovarian cancer can cause abdominal and pelvic symptoms, including pain and pressure. It's essential to consider in the differential due to its severity and the importance of early detection.

Sarcomas of the Uterus: These are rare malignant tumors of the uterus that can cause bleeding and pelvic pain. They are less common than other uterine cancers but should be considered in the differential diagnosis due to their aggressive nature.
Metastatic Cancer to the Uterus or Ovaries: In rare cases, cancers from other parts of the body can metastasize to the female reproductive organs, causing a variety of symptoms including bleeding and pain. This would be more likely in a patient with a known history of cancer.