Vaginal bleeding is one of the most common symptoms in gynecology. Except for normal menstruation, bleeding may occur in any part of women’s reproductive tract, including the uterine body, cervix, vagina and hymen, all of which are called vaginal bleeding. The common causes are as follows: 1. Ovarian endocrine dysfunction can cause uterine bleeding, such as anovulatory dysfunctional uterine bleeding and ovulatory menstrual disorders are caused by ovarian endocrine dysfunction, which is usually referred to as “menstrual irregularities”. In addition, follicle rupture during the intermenstrual period and a brief drop in estrogen level can also cause uterine bleeding.2. Common causes of pregnancy-related uterine bleeding include miscarriage, ectopic pregnancy, gestational trophoblastic disease, etc. mostly manifested as vaginal bleeding after menopause, in addition to partial residual placenta after delivery, placental polyps and poor uterine regeneration can lead to postpartum vaginal bleeding. 3.Inflammatory diseases of genitalia such as vulvar ulcer, vaginitis, cervicitis, cervical polyp, endometrial polyp, endometritis and pelvic inflammatory disease, etc. Other genital tumors that cause vaginal bleeding are mostly malignant, such as vulvar cancer, vaginal cancer, cervical cancer, endometrial cancer, uterine sarcoma, choriocarcinoma, etc. Injuries, foreign bodies and exogenous hormones can cause bleeding due to genital tract trauma such as vulvar or vaginal injuries, hymenal or vaginal injuries caused by sexual intercourse; placement of intrauterine device often causes abnormal uterine bleeding; in addition, improper use of exogenous hormones such as estrogen or progestin can also cause irregular uterine bleeding. 6. Vaginal bleeding related to systemic diseases such as thrombocytopenic purpura, aplastic anemia, leukemia, liver function damage, etc. can lead to uterine bleeding. The specific clinical manifestations are as follows: 1. Increased menstrual flow: manifested as more menstrual flow or prolonged menstrual period, but the cycle is basically normal, which is a typical symptom of uterine fibroids. Other symptoms such as adenomyosis, ovulatory disorders, and IUD placement may have increased menstrual flow. 2. Irregular vaginal bleeding in the cycle: mostly anovulatory dysfunctional uterine bleeding, but it can also be caused by early endometrial cancer. 3.Long-term persistent vaginal bleeding without any identifiable cycle: It is usually caused by malignant tumor of reproductive tract, and the possibility of cervical cancer or endometrial cancer should be considered first. 4.Vaginal bleeding after menopause: In women of childbearing age, pregnancy-related diseases such as miscarriage, ectopic pregnancy and gravidity should be considered first; in perimenopausal women, it is mostly due to anovulatory dysfunctional uterine bleeding, but it may also be caused by malignant tumors of the reproductive tract. 5.Vaginal bleeding with increased leucorrhea: generally, advanced cervical cancer, endometrial cancer or submucosal fibroid with infection should be considered. 6.Bleeding after sexual intercourse: if fresh blood appears immediately after sexual intercourse, the possibility of early cervical cancer, cervical polyp or submucosal fibroid should be considered. 7.Intermenstrual bleeding: If it occurs 14~15 days before the next menstrual period, lasting for 3~4 days, and the blood volume is very small, it is mostly ovulatory bleeding. 8. Pre- or post-menstrual spotting bleeding: A small amount of vaginal bleeding or a very small amount of maroon vaginal discharge for several days before and after menstruation can be seen as ovulatory menstrual disorders or as a side effect of intrauterine device placement. In addition, similar conditions may occur in endometriosis. 9.Vaginal bleeding years after menopause: If the bleeding is very small and lasts for 2-3 days, it is mostly caused by the shedding of endometrium after menopause or senile vaginitis; if the bleeding is large, persistent or repeated, the possibility of endometrial cancer should be considered. 10.Intermittent vaginal discharge of blood: Fallopian tube cancer may lead to this condition. 11.Vaginal bleeding after trauma: It mostly occurs after riding span injury, and the bleeding volume may be more or less. In addition, age is an important reference for the diagnosis of vaginal bleeding. Small amount of vaginal bleeding in newborn baby girls a few days after birth: it is caused by the sudden drop of estrogen after leaving the mother’s body and the endometrial lining is shed. Vaginal bleeding in young girls should be considered as a possibility of precocious puberty or malignant tumor of the genital tract. Vaginal bleeding in adolescent girls is mostly due to anovulatory dysfunctional uterine bleeding. Vaginal bleeding in women of childbearing age should be considered for pregnancy-related disorders. Vaginal bleeding during the transition to menopause is most often anovulatory dysfunctional uterine bleeding, but malignancy of the reproductive tract should be ruled out first.