Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is an endocrine and ovulatory disorder, not simply “ovarian cysts.” Its core pattern is androgen excess, insulin resistance, and disrupted follicle development that produces chronic oligo-ovulation or anovulation. Normally, one ovarian follicle matures and ovulates. In PCOS, follicular development repeatedly stalls before ovulation. The ovary may accumulate many small immature follicles on ultrasound, but these are not true pathologic cysts. A person can have PCOS without polycystic-appearing ovaries, and polycystic ovarian morphology alone does not establish PCOS. Insulin resistance often intensifies the disorder. Higher circulating insulin promotes ovarian androgen production and can reduce sex hormone-binding globulin, leaving more active androgen available in the circulation. The result may be hirsutism, acne, scalp hair thinning, and menstrual irregularity. When ovulation does not occur, the corpus luteum does not form and progesterone production is inadequate. Estrogen stimulation of the endometrium continues without the usual cyclic progesterone exposure. This explains both unpredictable bleeding and the increased risk of endometrial hyperplasia with prolonged untreated anovulation. PCOS can reduce fertility because ovulation is unpredictable, but it does not mean pregnancy is impossible....