Polycystic ovarian syndrome (PCOS) is a complex endocrine disorder characterized by a hyperandrogenic state with chronically elevated leutenizing hormone levels and normal to decreased follicle stimulating hormone levels. It is manifest by the clinical symptoms of obesity, hirstuism, amenorrhea, and infertility. While there are typical radiologic findings, the diagnosis of PCOS is made on the basis of the clinical history, biochemical analysis and, if available, histological evaluation of ovarian tissue.

Polycystic ovaries are best demonstrated on transvaginal ultrasound which in 50% of cases shows bilateral enlarged ovaries of 2-5 times normal volume, with multiple (>5) cysts in a subcortical position each measuring less than 1 cm. This gives a typical "string of pearls" appearance on US examination. The surface of the ovary is smooth and thickened despite the multiple cystic lesions in the periphery. An echogenic stroma may be present. As this is a clinical and laboratory diagnosis it is important to note that a third of patients will have normal ovarian volumes and a quarter will show no evidence of cyst formation.


In 1935, Stein and Leventhal reported the association of amenorrhea, hirsutism, infertility, and polycystic ovaries:
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