Polycystic ovarian syndrome: a misnomer for an enigmatic disease

A literature search on PubMed on 3rd May 2009 revealed 3696 citations for the term ‘polycystic ovarian syndrome’ (PCOS) and 8486 for ‘polycystic ovary’. Despite the size of this database, which will undoubtedly continue to grow, many questions remain unanswered regarding the enigma that is PCOS. Does a woman have to have polycystic ovaries to have the syndrome? What exactly is a polycystic ovary and what differentiates it from a multifollicular ovary? Do true anatomic and histological differences exist and are these important clinically? The name itself introduces the misconception that the ovary contains multiple cystic structures. This stems from the seminal work by Stein and Leventhal who in 1935 described the association between specific ovarian changes, typified by a thickened cortex, a prominent theca and multiple ‘cystic follicles’, in seven women suffering from amenorrhea and hirsutism1. These features were sufficient to make a diagnosis of PCOS, but, at the time, required direct visualization of the ovaries by laparotomy together with histological confirmation through biopsy. The introduction and development of ultrasound allowed scientists and clinicians to assess the ovaries noninvasively and so began the revolution which resulted in the numerous publications evident today2,3. More than 70 years after the syndrome was first described there is still much debate and conjecture as to what constitutes a polycystic ovary and the syndrome. We now know that the ‘cysts’ are in fact healthy antral follicles whose growth and maturation has been inhibited by low levels of follicle stimulating hormone (FSH)4. Recent evidence suggests that there may be an intrinsic abnormality of folliculogenesis that also affects the gonadotropinindependent stages of follicle development and the preantral follicle population, changes whose detection is beyond the capabilities of conventional ultrasound. This Editorial focuses on the ultrasound component of the syndrome and raises several clinical questions pertinent to diagnostic imaging, discussing how to define a polycystic ovary and the implications of the diagnosis for the patient. Defining the syndrome: the swing of the pendulum