Diagnosing polycystic ovary syndrome (PCOS) involves a combination of clinical assessment and laboratory tests. Criteria for diagnosis usually include irregular menstrual cycles, hyperandrogenism (excess male hormones), and polycystic ovaries visible on ultrasound. Blood tests to measure levels of androgens, insulin, and other hormones are crucial in confirming the diagnosis. A thorough evaluation of symptoms like acne, hirsutism, and weight gain is also essential.