What is the most likely diagnosis for a 17-year-old female who has never had her menses?

The diagnosis of primary amenorrhea is appropriate in this case because it refers specifically to the condition where a person has not begun menstruating by the age of 15 or within five years of breast development. In this scenario, the 17-year-old female has never experienced her menses, which falls under the definition of primary amenorrhea.

This diagnosis is significant as it prompts further investigation into possible underlying causes, such as hormonal imbalances, anatomical abnormalities, or genetic conditions. The age of the individual is crucial, as it helps to categorize the type of amenorrhea, and since this young woman has not had her period by 17, primary amenorrhea is the most fitting diagnosis.

In contrast, conditions like secondary amenorrhea would apply if the individual had previously menstruated but then stopped for a period of time. Menorrhagia refers to heavy menstrual bleeding and is not applicable here, as the patient has not experienced menstruation at all. Polycystic ovary syndrome may cause irregular menstrual cycles but would not be diagnosed without previous menstruation.