emergency department (ED) is not warranted However, the ED physician assures appropriate follow-up as adolescents who report oligomenorrhea at baseline (defined as an average cycle length of 42 to 180 days), the developing regular cycles is guarded and this compliant may be the earliest sign of a medical condition After years of follow-up, more than half will continue to have abnormally long cycles Adolescents with oligomenorrhea that has persisted for longer than years after menarche or that involves three or more cycles longer than 42 days during the past year are candidates for further diagnostic evaluation, although ordinarily this can be accomplished in an outpatient setting Postpartum Breastfeeding is a physiologic cause of prolactin secretion and oligomenorrhea Iatrogenic Hyperprolactinemia causing oligomenorrhea and galactorrhea can have several etiologies: drugs (particularly antipsychotic agents), discontinuation of hormonal contraceptive agents, stimulation of the breasts, and excessive secretion of prolactin itself (e.g., primary hypothyroidism, pituitary adenoma) Drugs produce hyperprolactinemia by blocking pituitary dopamine receptors or interfering in other ways with dopaminergic or serotoninergic central nervous system pathways