What are polycystic ovaries (PCO)?

PCO are ovaries which contain an excessive number of primordial follicles. Primordial follicles are tiny fluid filled sacs which contain the eggs. An ultrasound of the ovaries during the reproductive years usually shows on average 4-12 follicles in each ovary. When more than 15 follicles are present, the ovary is called “polycystic”.

What is the cause of polycystic ovaries (PCO)?

In a normal menstrual cycle there are usually 5-10 follicles at the beginning of the cycle. Later in the cycle, usually around day 14, one follicle gets bigger (leading follicle) and shortly thereafter ovulation takes place with release of the egg. The remaining follicles regress and disappear before the next cycle. These events are usually after every 4 weeks and result in the monthly menstrual bleed. In women with PCO, not all of the follicles regress each cycle and therefore there is an increase in number with successive cycles. Despite extensive research no single cause explains this variation from normal.

Polycystic ovaries vs polycystic ovarian syndrome

Polycystic ovaries should not be confused with polycystic ovarian syndrome (PCOS). PCOS is a condition that results from a disturbance of blood hormones, and may present with weight gain, acne, irregular or infrequent periods, and excess hair growth.

What causes polycystic ovarian syndrome (PCOS)?

In women with PCOS, an increase in androgen (hormone) levels disrupts the normal cyclical sequence of events within the ovary. Instead, no leading egg develops and ovulation does not occur. There is a build up of small immature follicles over time and symptoms (listed above) may become apparent.

This is not a serious condition. In fact the vast majority of patients do not require any form of treatment.

If, however, you are having difficulty getting pregnant or having menstrual problems there is a wide range of treatment options and most have high success rates. These may be discussed fully with your family doctor or specialist.