In presence of secondary sexual characters cause screening for primary amenorrhea is done at

Primary amenorrhoea is defined as the absence of secondary sexual characters by 14 yrs of age or absence of menarche in the presence of secondary sexual characters till 16 yrs of age, In the sequence of pubeal development the changes are as follows thelarche, increased growth spu, pubarche, menarche. As menarche is the last stage ,in case secondary sexual characters have developed to account for constitutional delay investigation is begun at 16 years.