the Stein–Leventhal syndrome) Although hirsutism and obesity are classic features of PCOS, many adolescent patients with oligomenorrhea and the endocrinologic abnormalities of PCOS lack one or both of these signs Patients with PCOS are a heterogeneous group with varying combinations of these features An adolescent with PCOS may present to the ED with heavy abnormal uterine bleeding after several months of amenorrhea due to anovulatory cycles (see Chapter 79 Vaginal Bleeding ) Few adolescents with clinical and biochemical evidence of PCOS have palpably enlarged ovaries, and their hyperandrogenism is typically mild There are no distinct criteria for the diagnosis of PCOS in adolescents and currently, adolescents are diagnosed according to adult standards Although several societies have published criteria guidelines for PCOS in adult women, the 2003 Rotterdam and the 2009 Androgen Excess Society’s criteria are considered more applicable for adolescents Table 51.2 provides both 2003 Rotterdam and 2009 Androgen Excess Society’s criteria for the diagnosis of PCOS In 2012, a PCOS consensus workshop in Amsterdam reevaluated the Rotterdam criteria specifically for diagnosing adolescents The expert consensus was as follows: all three criteria should hold true to diagnose an adolescent, oligomenorrhea or amenorrhea should be present for at least years after menarche (or primary amenorrhea at 16 years old), and hyperandrogenemia should be biochemically rather than clinically diagnosed Similarly, the Pediatric Endocrine Society (PES) published an expert consensus in 2015 regarding diagnosis of PCOS in teenagers warning about pitfalls of overdiagnosis given the overlap of PCOS criteria in adults with normal pubertal development The pathophysiologic basis for PCOS is incompletely understood However, the principal endocrinologic abnormalities involved are chronic anovulation, ovarian hyperandrogenism, and, in many affected patients, insulin resistance Increased androgen production from the ovaries, adrenal glands, and peripheral conversion and high levels of free estrogen interferes with the hypothalamic– pituitary–ovarian feedback system, causing irregular menses PCOS has been associated with an increased risk of metabolic dysfunction which can start during puberty and lead to significant morbidity and mortality