A little redness after three days of menstruation is considered to be related to the fact that menstruation has not been completely cleaned up, and cancer screening should be avoided at this time, which may cause errors in the results. Generally speaking, women should pay more attention to their own health, and can go to the hospital regularly for cancer screening, especially cervical cancer screening, to prevent cervical cancer. However, if a woman has a reddish color after three days of menstruation, it is considered to be related to the fact that her menstrual flow is not complete and not thoroughly cleared. If a woman undergoes cancer screening when her menstrual period is not yet clean, it may affect the results of the test because during cervical cancer screening, cell tissues in the vagina will be extracted to determine whether there is any possibility of cancer. If menstruation is not clean, it can cause contamination of the specimen and error in the results. Therefore, women should go to the hospital for cancer screening after their menstruation is completely clean, and avoid using medicines to clean the vagina before the test, so as not to affect the test results.