Amenorrhea can be sub grouped as primary or secondary. Primary amenorrhea is either the absence of periods by the age of 14 in the absence of growth or development of secondary sexual characteristics (presence of axillary or pubic hair, breast development or growth). Or, absence of periods by the age of 16 regardless of growth or development of secondary sexual characteristics. Secondary amenorrhea is defined as absence of periods for 6 months in a woman previously menstruating regularly.
Primary Amenorrhea: Clinicians find it useful to classify the causes of primary amenorrhea based on the presence of secondary sexual characteristics (breast) and female internal genitalia (uterus). The findings on physical examination can alert the clinician of possible causes and indicate which laboratory tests should be performed.