If the blood is bright red during menstruation, it means that there is an increase in arterial blood in menstrual blood. The increase in arterial blood may be caused by functional uterine bleeding, or submucosal fibroids, or large fibroids between the muscle walls. Therefore, it is an abnormality because normally 3/4 of menstrual blood is venous blood, so menstrual blood is not bright red, but dark red. It is recommended to go to the hospital for a timely examination to find out if there is a pathological change in the reproductive system that causes this condition, and then give the appropriate treatment according to the examination results. In addition, women’s menstruation is a sign of their health, so it is important to actively observe the volume, color and timing of menstruation in daily life, and to provide timely treatment if abnormalities occur.