Primary amenorrhoea

This is the failure to start menstruating. If this occurs in a 16 year old (or in a 14 year old who has growth failure or absence of secondary sexual characteristics) then this requires investigation. For menstruation to occur there must be a functioning hypothalmic-pituitary axis and no structural abnormalities that may prevent menstruation e.g. uterine agenesis, imperforate hymen.