Polycystic Ovarian Syndrome

What is polycystic ovarian syndrome?

Polycystic ovarian syndrome (PCOS) is a common ovarian disorder characterized by the presence of an increased number of small ovarian cysts (called follicles). These are tiny fluid-filled sacs that normally contain the eggs. As a result of the increased hormonal activity of these cysts, women with PCOS experience irregular menstrual cycles, subfertility, acne, excess body hair and weight gain.

Polycystic Ovarian Syndrome

How does PCOS develop?

Normally, all women of childbearing age have about 5 - 7 small follicles in each ovary, each containing an immature egg. With the beginning of each menstrual cycle, these follicles start to grow in an attempt to reach maturation and hatch the egg. However, only one follicle (called the leading follicle) will outgrow the others and will be selected for full development. The remaining follicles will degenerate and eventually disappear. The leading follicle will continue to grow until it reaches about 2 cm in diameter when it is ready to release the egg, a process called ovulation. As the other follicles disappear new ones will emerge to replace them in preparation for the next cycle. This means that the ovary maintains a constant number of small follicles throughout the cycle.

In PCOS, the ovary contains 2 - 3 times the normal number of follicles (usually more than 12) in each ovary. This happens as a result of failure of selection of a leading follicle i.e. none of the follicles grows to reach maturation. As a result, all the follicles escape degeneration and persist in the ovary. As new follicles continue to emerge with persistence of the older ones, the total number of follicles in each ovary continues to increase. These follicles are hormonally active producing mainly the male hormone (androgens). This will result in the release of high levels of androgens in the blood causing some manifestations such as excess body hair, acne, greasy skin and baldness.

Image: Laparascopic view of the ovary: Normal Ovary (left), Polycystic Ovary (right)

What causes PCOS?

Despite decades of extensive research into PCOS, its cause remains largely unexplained. There are three main theories explaining PCOS: firstly, it is thought that the fault could be in the ovary causing excess androgen production from the follicles resulting in failure of ovulation. The second theory suggests that the fault lies in the pituitary gland, which is situated in the base of the brain and normally regulates the function of the ovary. In women with PCOS, the pituitary secretes excess amounts of a hormone called LH, which stimulates the ovarian follicles to release excess male hormone resulting in failure of ovulation. The third theory speculates that PCOS is caused by a fault in insulin function called "insulin resistance". Insulin resistance is a condition in which normal amounts of insulin are inadequate to produce normal insulin actions on various types of body cells due to inability of these cells to respond to insulin. One of insulin's main functions is to get body cells to "open up" to take in glucose. Insulin resistance happens when the cells essentially don't open the door when insulin comes knocking. When this happens, the body secretes more insulin to overcome this resistance and to allow the cells to take in and utilise glucose. This usually results in increased insulin in the circulation (called hyperinsulinaemia). This excess insulin is thought to stimulate the ovarian cells to produce excessive amounts of the male hormone (androgen), which could cause failure of ovulation.

PCOS and Fertility

As described above, the presence of an increased number of small cysts in the ovary is related to the ovary's failure to produce the egg (ovulate) regularly in a cyclical pattern i.e. every month. As a result women with PCOS either experience a complete absence of ovulation or may ovulate very infrequently (every 2 - 3 months). Women seeking a pregnancy will therefore experience difficulty. However, the good news is that there is successful treatment for subfertility associated with PCOS (as discussed below).

How can PCOS be diagnosed?

A woman will be diagnosed to have PCOS if she fulfils two of the following three criteria:

  1. Infrequent or absent ovulation (egg production), usually associated with irregular menstrual cycles. Typically, the majority of women with PCOS have a period every 2-3 months. About 20% have no period at all and 15% have apparently regular cycles.
  2. Signs of excess male hormone such as increased facial hair and/or acne. Some women will only have an increased level of androgens in their blood without any external features.
  3. The presence of an increased number of the small ovarian cysts on ultrasound scan (>12 per ovary) or an increased ovarian volume (> 10 CC).

How can PCOS be managed?

Management of PCOS depends on what the patient presents to her Doctor with i.e. on the symptoms that concern her the most e.g. infertility, facial hair, acne, irregular menses or excess weight gain.

Management of subfertility related to PCOS:

Lack of ovulation (egg production), usually referred to as anovulation, is a common cause of infertility in women accounting for about 1 in 4 of all cases. It can arise from a number of causes, of which polycystic ovarian syndrome (PCOS) is by far the commonest and accounts for about 80% of all cases.

Before any medical treatment, women with PCOS who are overweight are strongly advised to reduce their BMI below 30. This is crucial for 2 reasons, firstly overweight woman do not respond well to induction of ovulation. The second reason is that overweight increases the risks of pregnancy complications such as miscarriage, pre-eclampsia and preterm delivery.

The first line treatment to induce ovulation is clomiphene citrate tablets, which are given for 5 days in the beginning of the cycle. About 80% of patients ovulate in response to clomiphene and 40% will conceive. If clomiphene is not successful, the second choice for treatment is either a keyhole operation on the ovary called laparoscopic ovarian drilling or daily injections with a hormone called FSH to induce ovulation. If the patent is still not pregnant after all these treatments, IVF will be the last resort.

Metformin tablets, which are used for patients with diabetes, have been used to induce ovulation in women with PCOS, although this use has not been supported by good evidence. More recent research has shown that Metformin is not as effective as initially thought to be. It may be useful in women with PCOS who are overweight and having difficulty losing weight.

Saad Amer

Saad Amer MSc., FRCOG, MD
Consultant Gynaecologist

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