Irregular vaginal bleeding refers to vaginal bleeding that is not related to menstruation, and depending on the cause, age and lifestyle are risk factors. Normally, vaginal bleeding occurs only during menstruation. Any vaginal bleeding outside of the menstrual period is abnormal. The common causes of vaginal bleeding are in all of the following areas: 1. Endocrine disorders It is usually important to rule out organic lesions first. Women of childbearing age with vaginal bleeding should first exclude whether they have a history of improper use of contraceptives and other lesions of the reproductive organs. Relevant endocrine examinations, such as vaginal cytology smear or pathological examination of the endometrium, can be performed. In addition to the possibility of malignant tumor, menopausal bleeding is also partly due to endocrine disorders, although the ovarian secretion of estrogen is reduced, the adrenal glands can replace the secretion; sometimes it can also be due to exogenous use of drugs. 2. Tumors Both benign and malignant tumors of reproductive organs can cause irregular vaginal bleeding. Submucosal fibroids often have irregular bleeding, while intermural fibroids cause excessive menstruation. Various malignant tumors of the vagina, cervix and body of the uterus can have a small amount of bleeding or manifest as postmenopausal bleeding. Ultrasound examination will be helpful for diagnosis. 3. Genital inflammation Generally inflammatory bleeding is not too much and is often accompanied by abnormal leucorrhea. Inflammation of the vulva, ulcers, and urethral meatus can have a small amount of bleeding. Vaginal inflammatory conditions commonly include trichomonas vaginalis, mycotic vaginitis and senile vaginitis. The first two are characterized by their abnormal leucorrhea, while senile vaginitis often manifests as postmenopausal bleeding. Cervicitis may have contact bleeding, especially when there are cervical polyps, etc.; cervical ulcers cannot exclude tuberculosis or syphilitic lesions in addition to the possibility of cervical cancer; endometritis often occurs after abortion or full-term delivery with increased bloody leukorrhea; pelvic inflammatory disease is occasionally combined with irregular bleeding or excessive menstruation. Women of childbearing age should pay attention to the presence of abnormal tissues in menstrual blood, and it is advisable to bring the “meatus” mixed with blood to the hospital for pathological examination to clarify whether it is a miscarriage or ectopic pregnancy or gravidity. 5. Trauma Injuries to the vulva and vagina and foreign bodies in the vagina can cause bleeding. For those who bleed after sexual intercourse, the first consideration is cervical cancer, but this is also seen in cervicitis and senile vaginitis. In some postmenopausal women, the vaginal mucosa becomes fragile due to the decrease of estrogen level in the body, and it is easy to damage and bleed. 6.Vaginal bleeding related to contraception Irregular oral contraceptive pills and displacement of intrauterine contraceptive ring can cause irregular bleeding. 7. Systemic diseases Leukemia, aplastic anemia, thrombocytopenic purple scar or hepatic sclerosis, nephritis, etc. can cause excessive menstrual flow or uterine bleeding. For regular intermenstrual bleeding consider it as ovulatory bleeding, increased menstrual flow is commonly seen in uterine fibroids, followed by intrauterine device placement or adenomyosis, etc. Pre- or postmenstrual spotting bleeding is often a side effect of intrauterine device placement, and similar symptoms can occur in endometriosis. Irregularly cycled vaginal bleeding is mostly anovulatory, but care should be taken to exclude endometrial cancer. Prolonged vaginal bleeding without any discernible cycle is usually due to malignant tumors of the reproductive tract, with cervical cancer or endometrial cancer being the first consideration. Therefore, it is important to pay attention to this symptom and treat it promptly to avoid delaying the condition and causing adverse consequences.