Polycystic Ovarian Syndrome
Ovulation problems are a common cause of subfertility and gynaecological problems. To understand problems and difficulties with ovulation it is important to understand how normal ovulation works. Ovulation is defined as the production of an egg, preferably on a cyclical basis. This monthly production of an egg, which allows pregnancy in the female, is controlled by a number of factors.
Polycystic Ovary Disease (PCOD)
Polycystic ovary disease is a poor term to cover a spectrum of ovulation problems. Other terms for PCOD are Stein-Leventhal Syndrome (although this is now rarely used) and polycystic ovarian syndrome (PCOS), which is probably the best descriptor.
What is PCOS?
PCOS is essentially a disorganisation of ovarian function. Normal regulation of orderly egg growth and release in the ovary is disrupted by a number of influences from within the ovary and from outside it. Messenger hormone from the pituitary gland to the ovary is often unbalanced and insufficient to maintain egg growth in a single cycle. 70% to 80% of patients will have high LH levels.
LH is the messenger hormone which releases the egg. It is therefore possible that patients with PCOS may prematurely activate their egg release resulting in eggs that are prematurely aged. The higher levels of this LH hormone may also prematurely change the lining of the follicles where the eggs are growing thereby unbalancing hormone production from the follicles and contributing to infertility, which is often seen with this condition.
In many patients with PCOS there are increased levels of male-type steroid hormones circulating in the blood. These are produced mainly by the ovaries, which are acting in an abnormal way but are also produced in the fat tissue of the body. Many patients (50%) with PCOS have obesity as a central problem and the excessive fat tissue contributes to the abnormally high levels of male hormone production. These male hormones contribute to some of the symptoms and signs of PCOS including acne, abnormal hair growth and rarely, voice deepening.
If the abnormalities that occur in PCOS are to be understood it is very helpful to have a good understanding of the normal mechanisms of egg growth as described above.
A PCOS ovulation cycle
In the PCOS patient the ovary receives a series of very mixed messages from the pituitary gland. In the normal menstrual cycle each month a large number of very primitive egg cysts begin their development as follicles. Under normal circumstances only one of these will be selected to be “the egg of the month”.
In the patient with PCOS, due to the disorganised communication between the pituitary gland and the ovary and within the ovary itself, this process of appropriate egg selection does not occur. This means that at any one time there may be many small, developing follicles within the polycystic ovary but it will only be on rare occasions that one of these will develop into quite a large follicle which will produce and release a mature egg.
Patients with PCOS have disorganised egg development with fluctuating female and male hormone levels. Periods are therefore often irregular and when bleeding occurs it is often in irregular amounts of poorly controlled loss – It is not a true period, which follows the orderly release of an egg.
This very disorganised ovary also produces inappropriate amounts of male hormone, which contributes further to the problem. Lack of organised egg production means that the messages going back to the pituitary gland are inappropriate. As the pituitary gland is receiving very confusing communications from the ovary this worsens the problem as the pituitary gland sends down more confused messages to an already confused ovary.
As many patients with PCOS have excessive body weight, obesity can be an important factor. The fat tissue has the ability to produce both male and female hormones. Very obese patients can actually produce very large quantities of female hormone. The female hormone (mainly oestrogen) will return to the ovary and have an effect on the ovary like taking the oral contraceptive pill.
The oestrogen also has an effect on the pituitary gland and interferes with the pituitary gland’s ability to understand how the ovary is functioning. Excessive amounts of fat therefore worsen the problem of uncoordinated ovulation and often contribute to infertility. The female hormones produced in fat may affect the uterus and obese patients are much more likely to have irregular bleeding. Obesity is therefore also a risk factor for cancer of the lining of the womb due to the effect of these female hormones.
There is a relationship between PCO and sugar intolerance. Patients with PCO have a higher incidence of adult onset diabetes in later life and a higher chance of diabetes in pregnancy. There is an increasing trend to test PCO patients for sugar intolerance and sometimes treat them with anti-diabetic drugs.
