Introduction

Polycystic ovary syndrome (PCOS) is a heterogeneous collection of signs and symptoms that, gathered together, form a spectrum of a disorder with a mild presentation in some but a severe disturbance of reproductive, endocrine and metabolic function in others. The pathophysiology of PCOS appears to be multifactorial and polygenic. The definition of the syndrome has been much debated, with key features including menstrual cycle disturbance, hyperandrogenism and obesity (see Box 1.1). There are many extra-ovarian aspects to the pathophysiology of PCOS but ovarian dysfunction is central.

The joint European Society of Human Reproduction and Embryology (ESHRE)/American Society for Reproductive Medicine (ASRM) consensus meeting in 2003 agreed a refined definition of PCOS, namely the presence of two of the following three criteria: (1) oligo-ovulation and/or anovulation, (2) hyperandrogenism (clinical and/or biochemical), (3) polycystic ovaries; with the exclusion of other causes of menstrual cycle disturbance or androgen excess (see Table 1.1).

The morphology of the polycystic ovary has been defined as an ovary with 12 or more follicles measuring 2-9 mm in diameter and/or an increased ovarian volume (more than 10 cm3).

There is considerable heterogeneity of symptoms and signs among women with PCOS and, for an individual, these may change over time. PCOS appears to be familial and various aspects of the syndrome may be differentially inherited. Polycystic ovaries can even exist without clinical signs of the syndrome, which may then become expressed over time.