Is a routine blood test accurate during menstruation?

　　It is generally quite accurate to perform a routine blood test during menstruation, as it does not significantly affect the test results.

　　A complete blood count (CBC) primarily measures the white blood cell count, the percentage of neutrophils and lymphocytes, as well as the levels of hemoglobin and platelets, helping to identify whether there are conditions such as infection, anemia, or thrombocytopenia. Although some variations in CBC results may occur during menstruation, these deviations are usually within the normal range.

　　If the situation is not an emergency, it is recommended that patients wait until three days after menstruation has ended before undergoing the test. This is because blood loss during menstruation can be significant, potentially leading to anemia, and drawing blood might cause physical discomfort.