The presence of putrid odor of menstrual blood is usually not a sign of cancer. After the endometrium undergoes cyclic exfoliation, blood and endometrial debris mix and are discharged from the vagina, which itself will have a bloody odor. If the amount of menstrual blood is small and stays in the vagina for too long, it may have a putrid odor. However, if the putrid odor is very strong and persistent, it may be caused by gynecological inflammation, such as bacterial vaginitis or trichomoniasis, or by lack of hygiene during menstruation, which may lead to bacterial breeding infection. If there is gynecological cancer, such as endometrial cancer, there will be purulent with blood body secretion from the vagina with foul odor, which is abnormal bleeding instead of menstrual blood, manifested as irregular vaginal bleeding, abnormal fluid discharge, pain, and lump. During menstruation, women’s immunity decreases and they are easily infected with various germs, so it is important to change tampons and underwear and wash the vulva regularly. Patients whose symptoms do not improve significantly may consult a gynecologist for examination.