During menstruation, blood can be drawn for routine blood tests and there will be no significant abnormalities. During menstruation, the uterine opening is slightly dilated and the endometrium and menstrual blood are discharged, so gynecological examination and sexual intercourse should not be performed during menstruation, otherwise retrograde infection may result, leading to endometritis and even pelvic inflammatory disease, etc. Intercourse during menstruation may cause menstrual blood to flow backwards, leading to endometriosis. Some women are afraid that a routine blood test during menstruation will lead to anemia, but this is actually incorrect. A menstrual bleeding of about 20-60 ml, more than 80 ml is called excessive menstruation, so the hemoglobin results during menstruation are basically the same as usual. However, during menstruation, the prolongation of clotting time will lead to prolonged bleeding time at the blood draw point, but this has no major impact, we can stop the bleeding by pressing for a while more.