The color of menstruation is often dark red, thin and moderate, not coagulated, no odor, the normal monthly menstrual volume is 20-60ml, when the menstrual volume is less than 20ml, dark red, considered as low menstrual volume, suggesting polycystic ovary syndrome, hyperandrogenemia and other diseases, through ultrasound and blood tests and other tests, to clarify the cause, the treatment of the cause. 1, polycystic ovary syndrome: clinical manifestations of menstrual disorders, mostly manifested as Menstrual scarcity or amenorrhea, i.e. symptoms of dark red menstruation with low volume. For obese type patients, diet should be controlled and exercise should be increased to reduce weight and waist circumference. Contraceptive pills can be taken under the guidance of a doctor, as well as the application of ovulation-promoting drugs, etc. If necessary, surgical treatment, i.e. laparoscopic ovarian perforation, can be taken. 2. Hyperandrogenemia: The more common clinical manifestations are menstrual changes such as scanty menstruation, amenorrhea or dysfunctional uterine bleeding, with dark red menstruation with low volume, which may also be accompanied by non-ovulation and infertility. 3. Hyperprolactinemia: The manifestations are menstrual disorders, secondary amenorrhea, which may be accompanied by dark red menstruation The symptoms of low volume, serious cases may have reduced libido, genital atrophy, osteoporosis. The symptoms may include reduced libido, genital atrophy and osteoporosis. Drug treatment can be given, and surgery is required in severe cases; 4. Tuberculous endometritis: the clinical manifestations are normal menstrual cycle and increased menstrual volume in the early stage, gradually prolonged menstrual cycle and reduced menstrual volume in the later stage, and eventually very little brown menstrual volume and even amenorrhea. It can be treated with oral anti-tuberculosis drugs under the guidance of a doctor; 5. Other: gynecological examination, low gonadal function, etc. can lead to low menstrual flow, and it is recommended to go to the hospital in time for a clear diagnosis and treatment.