As menstrual blood may be leaked in the urine given during menstrual period, culture and direct microscopic analyses are affected. It isn't possible to distinguish where the erythrocytes to be seen in microscopic analysis stem from. As the microorganisms, which are normally available in the menstrual blood and vagina, may contaminate with the urine, which is expected to be sterile, causing misleading results. Therefore, urine analysis and culture are not performed in menstrual period.