Why does intercourse cause bleeding before and after menstruation?

Generally, bleeding after intercourse around the time of menstruation may be caused by hymenal injury, endocrine dysfunction, ovulation bleeding, vaginitis, cervical polyps, or other reasons. Specific analyses are as follows:

1. Hymenal Injury

The most common cause is rupture of the hymen during first-time intercourse. This may be accompanied by pain and bleeding, though the amount of blood is usually minimal. This is a normal phenomenon. It is recommended that patients rest adequately and no special treatment is required.

2. Endocrine Dysfunction

Endocrine dysfunction can lead to menstrual irregularities. For example, insufficient luteal function may cause slight shedding of the endometrium and result in light bleeding. This is considered normal. Patients are advised to maintain a light diet, drink plenty of water, and the condition typically resolves gradually after menstruation ends.

3. Ovulation Bleeding

Bleeding during ovulation may be related to hormonal fluctuations before and after ovulation. A temporary drop in estrogen levels causes part of the endometrium to shed due to lack of hormonal support, resulting in regular vaginal bleeding. This is a normal phenomenon. Patients should maintain good hygiene and gently clean the external genital area as needed.

4. Vaginitis

If patients do not maintain proper sexual hygiene, bacteria may invade the vagina and cause vaginitis. Inflammation can lead to congestion and edema of the vaginal mucosa, resulting in post-coital (contact) bleeding, abnormal vaginal discharge, and itching of the external genitalia. Patients may take medications such as metronidazole tablets or tinidazole tablets under medical supervision. Additionally, maintaining sexual hygiene and frequently changing and washing underwear is important.

5. Cervical Polyps

If a patient has pre-existing cervical polyps, intercourse may cause the polyp to rupture, leading to post-coital bleeding, increased vaginal discharge, and abdominal pain. Treatment may involve surgical removal of the cervical polyp. Patients should also get adequate rest and avoid excessive fatigue.

In addition, post-coital bleeding may also be associated with conditions such as cervical cancer or submucosal uterine fibroids. If any discomfort occurs, patients should seek medical attention at a正规 hospital to determine the underlying cause and receive timely treatment under a doctor's guidance.