1.Intramural fibroids can cause excessive menstruation and prolonged bleeding due to increased deformation of the uterine cavity and increased endometrial area; 2.Fibroids obstruct uterine contraction or affect blood flow causing chronic pelvic congestion, resulting in excessive bleeding; 3.Fibroids combined with endometrial hyperplasia or polyp formation due to ovarian anovulation; 4.Submucosal fibroids can cause excessive menstruation due to increased mucosal area and surface ulceration and infection. The combination of chronic pelvic inflammatory disease may lead to congestion and increased menstruation; 6. Generally speaking, uterine fibroids cause bleeding mainly by increased menstruation, intermenstrual bleeding is uncommon in simple fibroids, if it occurs, it often indicates the presence of comorbidities such as malignant changes, polyps, submucosal fibroids, endothelial hyperplasia and so on. Therefore, when intermenstrual bleeding is seen, further investigations should be performed to rule out malignant changes. Uterine fibroids not only cause irregular bleeding, but may also cause some other serious complications, which must be treated promptly in a regular hospital by an expert.