What defines primary amenorrhea?

Primary amenorrhea is defined as the absence of menstruation by a certain age, specifically when it comes to secondary sexual characteristics. The correct definition indicates that if a girl has not experienced her first menstrual period (menarche) by age 15, but has developed secondary sexual characteristics, this condition is termed primary amenorrhea. It highlights the significance of assessing both the onset of menses and the presence of secondary sexual development to categorize the clinical situation correctly.

In contrast, the other choices do not accurately depict the criteria for primary amenorrhea. The absence of menses by age 13 with no secondary sexual development indicates a different clinical concern that might suggest a delay in sexual maturation. Additionally, the menstrual cycle absence for a certain number of cycles, such as three or six months, pertains to secondary amenorrhea, where a woman who has had prior menstrual cycles fails to continue menstruating. Thus, understanding the context around the age and associated characteristics is crucial in recognizing primary amenorrhea accurately.