Primary amenorrhea is defined as the absence of menses at age 15 years in the presence of normal growth and secondary sexual characteristics. The identification of primary amenorrhea should always prompt a thorough evaluation to identify a cause . At age 13 years, if no menses have occurred and there is a complete absence of secondary sexual characteristics such as breast development, evaluation for primary amenorrhea should begin. In addition, some girls with secondary sexual characteristics may present before age 15 years with amenorrhea and cyclic pelvic pain. These girls should be evaluated for possible outflow tract obstruction.
Amenorrhea (absence of menses) can be a transient, intermittent, or permanent condition resulting from dysfunction of the hypothalamus, pituitary, ovaries, uterus, or vagina. It is often classified as either primary (absence of menarche by age 15 years) or secondary (absence of menses for more than three months in girls or women who previously had regular menstrual cycles or six months in girls or women who had irregular menses). Missing a single menstrual period may not be important to assess, but amenorrhea lasting three months or more and oligomenorrhea (fewer than nine menstrual cycles per year or cycle length greater than 35 days) require investigation. An intermenstrual interval greater than 45 days is considered abnormal in adolescent girls who are ≥2 years postmenarche. The etiologic and diagnostic considerations for oligomenorrhea are the same as for secondary amenorrhea.The epidemiology and causes of secondary amenorrhea are reviewed here. The evaluation and management of secondary amenorrhea and the causes, evaluation, and management of primary amenorrhea are discussed separately.