The light color of menstrual blood is often clinically caused by the following reasons: 1. inflammation of the endometrium, when the endometrium has inflammation will lead to increased local exudation, so it will make the blood dilute, it will be manifested as the light color of menstrual blood, and in daily life there will also be repeated lower abdominal pain, usually vaginal discharge will be more, yellow color, after ultrasound examination of the endometrium will appear echogenic uneven. 2. The color of menstrual blood will also become lighter because of the reduction of red blood cells in the blood due to severe anemia. Therefore, clinically, if the menstrual blood becomes lighter, ultrasound and blood tests are recommended.