Cryptomenorrhea is a condition where menstruation occurs but is not visible due to an obstruction of the outflow tract. Specifically the endometrium is shed, but an congenital obstruction in the vagina or on part of the hymen retains the menstrual flow. A patient with cryptomenorrrhea will appear to have amenorrhea but will experience cyclic menstrual pain. Surgical correction will be indicated. The menstrual cycle is the periodic change in a womans body that occurs every month between puberty and menopause and that relates to reproduction. ... The endometrium is the uterine membrane in mammals which is thickened in preparation for fertilization, and into which a fertilized egg is implanted upon its arrival into the uterus. ... Human female internal reproductive anatomy The vagina (from the Latin for sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female mammals, or to the cloaca in female birds and some reptiles. ... The hymen (or maidenhead) is a membrane which completely or partially occludes the vaginal opening in human females. ... Amenorrhoea (BE) or amenorrhea (AmE) is the absence of a menstrual period in a woman of reproductive age. ...