In the UK, up to 33% of women have polycystic ovaries (i.e. 10 or more follicles per ovary detected on ultrasound) (1).

Of these, an estimated 33% have polycystic ovarian syndrome (PCOS), generally defined in the UK as polycystic ovaries together with one or more characteristic features (hirsutism, acne, male-pattern baldness, amenorrhoea or oligomenorrhoea, or raised serum concentrations of testosterone and/or luteinising hormone) (2,3).

In polycystic ovarian syndrome the associated metabolic abnormalities (abnormal serum lipid concentrations and insulin resistance) also put some women at an increased risk of developing diabetes mellitus (4).

According to the more recent Rotterdam diagnostic criteria, PCOS can be diagnosed if 2 out of the following 3 are present (but only when other aetiologies have been excluded) (5):

• polycystic ovaries (either 12 or more peripheral follicles or increased ovarian volume (greater than 10 cm3)
• oligo- or anovulation
• clinical and/or biochemical signs of hyperandrogenism

Thyroid dysfunction, congenital adrenal hyperplasia, hyperprolactinaemia, androgen-secreting tumours and Cushing’s syndrome must to be excluded before making a diagnosis of PCOS (5).