A menstrual cup is a feminine hygiene device that is inserted into the vagina during menstruation. Its purpose is to collect menstrual fluid (blood from uterine lining) and prevent its leaking onto clothes. Menstrual cups are usually made of flexible medical grade silicone and shaped like a bell with a stem. The stem is used for insertion and removal. The bell-shaped cup seals against the vaginal wall just below the cervix.