Cervicitis: This is often the most common cause of post-coital bleeding, especially if it's related to an infectious etiology such as chlamydia or gonorrhea. The physical trauma from intercourse can cause bleeding from an already inflamed cervix.

Cervical Ectropion: A condition where the glandular cells lining the inside of the cervical canal are everted to the outside of the cervix, which can cause bleeding after intercourse due to the fragility of these cells.
Cervical Polyps: These are growths on the cervical canal that can bleed easily, especially after sexual intercourse.
Vaginal Dryness or Atrophy: Common in postmenopausal women, the lack of estrogen can lead to thinning and drying of the vaginal walls, making them more susceptible to bleeding during intercourse.

Cervical Cancer: Although less common, it's crucial to rule out cervical cancer as a cause of post-coital bleeding. Any abnormal vaginal bleeding, especially in women over 35 or those with a history of abnormal Pap smears, warrants further investigation.
Endometrial Cancer: Though more typically associated with postmenopausal bleeding, endometrial cancer can occasionally present with bleeding after intercourse, especially if there's associated endometrial hyperplasia.

Vaginal Cancer: A rare type of cancer that can cause bleeding, including after sexual intercourse.
Trauma: Physical trauma to the vagina or cervix, which could be accidental or non-accidental, and presents with bleeding after intercourse.
Blood Clotting Disorders: Underlying coagulopathies can increase the risk of bleeding from minor trauma, such as that occurring during sexual intercourse.
Invasive Mole or Choriocarcinoma: In pregnant women, these rare conditions can cause abnormal bleeding, including after intercourse, though they are more commonly associated with other symptoms like a missed period or abnormal ultrasound findings.