In this blog for non-medical readers, Cochrane UK’s Senior Fellow in General Practice, Lynda Ware, looks at polycystic ovary syndrome (PCOS) and the evidence on treatments.
Page last updated 23 December 2022
What is polycystic ovary syndrome (PCOS)?
PCOS is common. It is estimated that somewhere between 5 and 10% of women of reproductive age have it, although quoted figures vary widely. For some it is distressing and only too obvious. For others there are no outward signs of anything amiss.
There isn’t universal agreement on how best to diagnose PCOS. The most widely accepted criteria state that two out of the following three features should be present:
- absent or infrequent periods.
- raised male hormone levels (androgens). These can be measured in the blood and may cause symptoms such as hirsutism (unwanted excess hair growth).
- polycystic ovaries (PCO). These are ovaries that are larger than normal and contain multiple fluid-filled cysts.
As you can see, it is not necessary to have polycystic ovaries to have PCOS and, conversely, polycystic ovaries are not always associated with PCOS.
‘A gynaecological curiosity’
The earliest known description of PCOS was written by Vallisneri in 1721 in Italy when he described a ‘young married peasant woman, moderately obese and infertile, with two larger than normal ovaries, bumpy, shiny and whitish, just like pigeon eggs’.
It was not until 1935, when Stein and Leventhal presented a paper identifying the syndrome at a meeting of the Central A relationship between two characteristics, such that as one changes, the other changes in a predictable way. For example, statistics demonstrate that there is an association between smoking and lung cancer. In a positive association, one quantity increases as the other one increases (as with smoking and lung cancer). In a negative association, an increase in one quantity corresponds to a decrease in the other. Association does not necessarily mean that one thing causes the other. of Obstetricians and Gynaecologists in America, that PCOS began to evolve from being ‘a gynaecological curiosity’ to what is now considered a multisystem endocrine disorder. It was originally called Stein-Leventhal syndrome.
What causes PCOS?
The exact causes of PCOS are not known but it often runs in families and having a close female relative such as mother, sister or aunt with the condition makes it more likely to occur. There is also an association with obesity.
Hormones and PCOS
All women have small amounts of male hormones in their blood but in PCOS the ovaries often produce higher levels than normal, especially testosterone.
Women with PCOS are commonly found to be resistant to the action of insulin, a hormone that regulates blood sugar levels. To compensate for this, insulin levels rise and this in turn stimulates the ovaries to produce testosterone. Women who are overwight or obese have higher levels of insulin than normal.
Luteinising hormone (LH) from the anterior pituitary gland, may also be raised in PCOS. LH is a gonadotrophin which, alongside follicle-stimulating hormone (FSH), regulates the menstrual cycle, ovulation and fertility.
Some women with PCOS have low levels of sex hormone-binding globulin (SHBG) which binds to testosterone and reduces its effect.
A few women with PCOS have raised prolactin levels.
What are the effects of PCOS?
PCOS appears to be a spectrum of disorders, with some women having only mild symptoms whilst others are affected more severely.
Symptoms may include :
- irregular, infrequent periods or no periods at all
- hirsutism – unwanted facial and body hair
- loss of hair on the head
- weight gain and difficulty losing weight
- reduced fertility.
There is also a greater A way of expressing the chance of an event taking place, expressed as the number of events divided by the total number of observations or people. It can be stated as ‘the chance of falling were one in four’ (1/4 = 25%). This measure is good no matter the incidence of events i.e. common or infrequent. of certain long-term health problems:
- It is estimated that 10-20% of women with PCOS go on to develop diabetes. This risk is further increased in women with PCOS who are over 40, have a family history of diabetes, developed diabetes during pregnancy or are obese.
- High blood pressure. This is linked to insulin resistance and being overweight, rather than the PCOS itself, and can lead to cardiovascular disease.
- Cancer of the lining of the womb (endometrium). The endometrium becomes thicker if periods are infrequent and this may be associated with cancerous changes.
- Mood disorders such as depression.
- Snoring, obstructive sleep apnoea and fatigue.
What can be done to help?
Unfortunately, there is no cure for PCOS but often it can be managed without medical A treatment, procedure or programme of health care that has the potential to change the course of events of a healthcare condition. Examples include a drug, surgery, exercise or counselling. .
The mainstay of management is a healthy lifestyle, eating a healthy diet and exercising regularly. Losing excess weight is important and the aim should be to achieve a normal BMI (that is 19-25) since this can lower the risk of developing diabetes and heart problems and also improve fertility. It may also lower the risk of endometrial cancer, reduce acne and decrease excess hair growth.
Excess unwanted hair can be deeply distressing. There are various hair removal techniques such as depilatory creams, waxing, electrolysis and laser hair removal.
Women over 40 with PCOS should have yearly checks on their blood sugar levels and before the age of 40 if obese or there is a family history of diabetes. GPs will advise on blood pressure reviews and cholesterol checks. If irregular menstrual bleeding occurs or periods stop altogether, it may be necessary to have a pelvic ultrasound to assess the thickness of the endometrium and a gynaecological referral if there are any concerns.
Medical and surgical treatment options
Irregular or absent periods
The oral contraceptive pill or intermittent courses of a progestogen can be helpful in regulating menstruation. They also help reduce the risk of endometrial cancer developing. The intrauterine system (IUS), another hormonal contraceptive, helps prevent thickening of the lining of the womb but does not always promote regular bleeds.
Thankfully, many women with PCOS have no difficulty getting pregnant.
When problems do arise there are various courses of action.
Clomiphene citrate is usually the first line of Something done with the aim of improving health or relieving suffering. For example, medicines, surgery, psychological and physical therapies, diet and exercise changes. and it acts by stimulating ovulation. Letrozole and tamoxifen, drugs used to treat breast cancer, are sometimes prescribed in place of clomiphene.
Metformin is used to treat type 2 diabetes. It increases A measure of a screening or diagnostic test’s ability to correctly detect people who have the disease. to insulin and thereby reduces insulin and sugar levels in the blood. In PCOS it can help stimulate ovulation and regulate periods.
If none of the above treatments works, then gonadotrophins may be recommended or a surgical procedure called laparoscopic ovarian drilling (LOD). LOD is a technique that destroys ovarian tissue thereby decreasing testosterone levels and promoting ovulation.
Finally, assisted reproducion techniques such as IVF (in vitro fertilisation) or ICSI (intracytoplasmic sperm injection) may be considered.
Unwanted hair growth and hair loss
Certain medications which work by blocking testosterone or suppressing its production by the ovaries can be helpful. The oral contraceptives Dianette, Marvelon and Yasmin are examples; also cyproterone acetate, spironolactone, flutamide and finasteride.
Eflornithine (Vaniqa) is a cream, available on prescription, that can slow the growth of unwanted hair.
There are various treatments available both over-the-counter and on prescrition which can help reduce acne. Good advice can be sought from a pharmacist or GP.
What do Cochrane systematic reviews tell us?
There are over twenty published In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. in the Cochrane Library exploring PCOS. Half of these consider treatments, both medical and surgical, to improve fertility Outcomes are measures of health (for example quality of life, pain, blood sugar levels) that can be used to assess the effectiveness and safety of a treatment or other intervention (for example a drug, surgery, or exercise). In research, the outcomes considered most important are ‘primary outcomes’ and those considered less important are ‘secondary outcomes’.. Other reviews look at the impact of various interventions – medical, surgical and lifestyle changes – on the symptoms of PCOS.
Much of the evidence included in the reviews looking at the The ability of an intervention (for example a drug, surgery, or exercise) to produce a desired effect, such as reduce symptoms. and Refers to serious adverse effects, such as those that threaten life, require or prolong hospitalization, result in permanent disability, or cause birth defects. of treatments to improve fertility is of low or very low quality. This means that the results must be interpreted with caution.
Clomiphene and other antioestrogens for ovulation induction in polycystic ovarian syndrome (December 2016) finds that which probably result in more live births but a higher miscarriage The speed or frequency of occurrence of an event, usually expressed with respect to time. For instance, a mortality rate might be the number of deaths per year, per 100,000 people.. There appears to be no evidence of a difference in effectiveness between clomiphene and tamoxifen although letrozole probably results in more live births.
The Cochrane Review Metformin treatment before and during IVF or ICSI in women with polycystic ovary syndrome (December 2020) finds that Metformin may improve live birth rates compared to placebo but women are likely to encounter gastrointestinal side-effects. Studies which compared the effects of metformin to placebo/no treatment before or during IVF/ICSI treatment in women with PCOS found no conclusive evidence that metformin improves live birth rates. Metformin may reduce the The number of new occurrences of something in a population over a particular period of time, e.g. the number of cases of a disease in a country over one year. of ovarian hyperstimulation syndrome (OHSS). It is uncertain whether other insulin-sensitising drugs, such as rosiglitazone and pioglitazone, have the same effects.
When comparing the effects of clomiphene and metformin, results differ according to the BMI of the women. An improvement in clinical pregnancy and ovulation rates suggests that clomiphene citrate remains preferable to metformin for ovulation induction in obese women with PCOS.
The Cochrane Reviews are systematic reviews. In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome (September 2022) finds reliable evidence that “letrozole appears to improve live birth rates and pregnancy rates compared to clomiphene citrate when used to cause ovulation, followed by timed intercourse. There appeared to be no difference for miscarriage rate or multiple pregnancy rate. Ovarian hyperstimulation syndrome, a serious A harmful or abnormal outcome, for example death or vomiting, that occurs during or after the use of a drug or other intervention (e.g. surgery or exercise) but has not necessarily been caused by that intervention. of hormonal stimulation, was a very rare event and in most Clinical trials are research studies involving people who use healthcare services. They often compare a new or different treatment with the best treatment currently available. This is to test whether the new or different treatment is safe, effective and any better than what is currently used. No matter how promising a new treatment may appear during tests in a laboratory, it must go through clinical trials before its benefits and risks can really be known. it did not occur.”
There is no evidence of a difference in clinical pregnancy, live birth or miscarriage rates in women undergoing laparoscopic ovarian drilling (LOD) compared to medical treatment but there are fewer multiple pregnancies, finds the Cochrane Review Laparoscopic ovarian drilling for ovulation induction in women with anovulatory polycystic ovary syndrome (February 2020).
It is uncertain whether there is an advantage in performing ovarian drilling laparoscopically (LOD) or transvaginally with ultrasound guidance (UTND). It is also unclear whether adding gonadotrophins to UTND confers greater benefits compared to gonadotrophins alone. trials sure ovarian drilling
There is insufficient evidence to support the use of Chinese herbal medicine, find the authors of the Cochrane Review Chinese herbal medicine for subfertile women with polycystic ovarian syndrome (June 2021) or Acupuncture for polycystic ovarian syndrome (July 2019) to improve fertility. Similarly, it is uncertain whether the dietary supplement inositolis effective in increasing pregnancy and live birth rates when added to standard treatment before IVF or ICSI.
The authors of the Cochrane Review published in March 2019 found no studies looking at lifestyle changes in women with polycystic ovary syndrome and their effects on live birth, miscarriage and menstrual patterns.
There is guidance from the National Institute for Health and Care Excellence (NICE) on Fertility problems: assessment and treatment.
The same Cochrane Review lifestyle changes in women with polycystic ovary syndrome did find fifteen small studies to include in the review, with low quality evidence that reveals that a healthy lifestyle may result in weight loss and a reduction in male hormone in some individuals.
The Cochrane Review Metformin versus the combined oral contraceptive pill for hirsutism, acne, and menstrual pattern in polycystic ovary syndrome (August 2020) considers the role metformin might play in relieving the symptoms of PCOS. Data is the information collected through research. from trials comparing metformin with the oral contraceptive pill (OCP) were included. The The certainty (or quality) of evidence is the extent to which we can be confident that what the research tells us about a particular treatment effect is likely to be accurate. Concerns about factors such as bias can reduce the certainty of the evidence. Evidence may be of high certainty; moderate certainty; low certainty or very-low certainty. Cochrane has adopted the GRADE approach (Grading of Recommendations Assessment, Development and Evaluation) for assessing certainty (or quality) of evidence. Find out more here: https://training.cochrane.org/grade-approach is low or very low throughout and more robust evidence is required to be sure of benefits and harms.
Where does this leave us?
PCOS is a common disorder which can have devastating effects on a woman in terms of her appearance, self-esteem, fertility and long-term health. It is a multi-system endocrine disorder, which is poorly understood. Treatments are available but there is none that effects a cure. More research is needed to understand what causes this condition and how it may be effectively treated.
Lynda Ware has nothing to disclose.