PCOS stands for polycystic ovarian syndrome or polycystic ovary syndrome. It affects the ovaries and involves the female hormones which regulate the menstrual cycle, affect fertility and contribute to the sexual characteristics of women. Although ovarian cysts are usually present, hence the term polycystic ovary syndrome, many women with PCOS may not have any ovarian cysts.
The three key features of PCOS, of which at least two features are present, includes :
- excess of androgens – male sex hormones that are usually present in low concentrations in women
- irregular menstrual cycle – amenorrhea (no period) or oligomenorrhea (infrequent periods, often heavy)
- cysts in the ovaries – multiple
PCOS is often associated with infertility but this may not be a complication in every case of PCOS. Anovulation (no ovulation), however, is present in most cases. In addition, insulin resistance and impaired glucose tolerance is often seen in PCOS.
What Causes PCOS?
The exact cause of PCOS is unknown but risk factors usually include a family history of PCOS and other menstual disturbance, diabetes and pituitary dysfunction. Obesity is another key factor. While these risk factors are common to many cases, the trigger for the biochemical disturbance and clinical features of PCOS is not known.
The widely accepted mechanism behind PCOS is that the anterior pituitary gland secretes higher than normal amounts of LH (luteinizing hormone). This acts on the ovaries to stimulate the follicles to produce excess androgens. The high blood concentration of the androgens – testosterone, androstenedione, and dehydroepiandrosterone sulfate (DHEA-S) – affects ovulation. Low FSH (follicle-stimulating hormone) levels affects the way the ovaries deal with the androgens and this disrupts the levels of the female hormones like estrogen. This means that the ovary does not release an ovum (egg cell) as would be expected during the ovulation period prior to menstruation. This in turn results in persistent cysts.
Ovarian Cyst Size
Cysts in the ovarian follicles are not present in every case of PCOS. It can be easily detected by a transvaginal ultrasound and is often used as a means of monitoring the condition.
In PCOS there are multiple cysts which may vary between 0.5 to 1.5 centimeters (about 0.2 to 0.6 inches) in diameter. It is not uncommon for larger cysts to be present or a solitary massive cyst with numerous smaller cysts.
Apart from the presence and size of cysts, the ovaries are usually enlarged as much as twice the normal size. The superficial ovarian cortex is thickened and may even undergo fibrosis, while the corpus lutea may be absent.