Polycystic Ovary Syndrome (PCOS)

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Polycystic ovary syndrome (PCOS) is the most common endocrine disorder affecting women of reproductive age, affecting 10% of women.1

The pathophysiology of PCOS involves excessive androgen production and multiple ovarian cysts. Consequently, the main clinical features include anovulatory infertility, acne and hirsutism, irregular menstrual cycles, obesity and increased long term risks of cardiovascular events and endometrial cancer.

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The aetiology of polycystic ovary syndrome is largely unknown and multifactorial. The genetic inheritance of PCOS is heterogeneous and complex. However, it appears to be inherited in an autosomal dominant fashion. Post-natal obesity appears to be the leading environmental contributor.1

The pathophysiology of PCOS relates to excess androgen production, and this is usually due to one or both of:Β 

  • Excess LH (luteinising hormone) production: the anterior pituitary releases gonadotropin in response to gonadotropin-releasing hormone. This leads to excess androgen production by the ovaries.
  • Hyperinsulinemia and insulin resistance: excess insulin in the bloodstream promotes androgen production by the ovaries. Hyperinsulinemia may stimulate the ovary to over-produce testosterone and prevent the follicles from growing normally to release eggs. This causes the ovaries to become polycystic.

These are the most common hormonal abnormalities found in PCOS.

Most women with PCOS have β€œcysts” found on their ovaries. These are immature follicles which have had their ovulation phase arrested. This occurs due to an elevated baseline of LH and lack of LH surge (as in a normal menstrual cycle).3

It is important to note there is a difference between the radiological finding of β€œpolycystic ovaries” and the biochemical disturbances of polycystic ovarian syndrome. Each of these can exist in the absence of the other.

Risk factors

Risk factors for polycystic ovary syndrome include:1

  • Obesity
  • Diabetes mellitus
  • Family history of PCOS
  • Premature adrenarche (early onset of pubic hair)

Clinical features


PCOS usually presents in a woman around puberty, up to mid-20s.3

Typical symptoms include:

  • Hirsutism: excessive hair growth in women, especially affecting the face, chest and back. Hirsutism is the most common symptom, present in 60% of women with PCOS.3
  • Infertility
  • Acne
  • Menstrual cycle disturbance: manifesting as either oligomenorrhoea (reduction in menstrual bleeding, defined as <9 periods per year) or amenorrhoea (no menstrual bleeding)
  • Obesity and weight gain
  • Alopecia
  • Depression and other psychological disorders

Clinical examinationΒ 

Hirsutism is the most characteristic examination finding.3

Other clinical findings include the consequences of hyperandrogenism:

  • Acne
  • Hair loss and male pattern baldness

Women with PCOS also have an increased risk of metabolic syndrome resulting in:

  • Hypertension
  • Obesity
  • Acanthosis nigricans: as a result of insulin resistance (Figure 1)
Acanthosis Nigricans (as a result of insulin resistance in polycystic ovary syndrome)
Figure 1. Acanthosis nigricans.

Differential diagnoses

There are several differentials to consider in a patient with suspected PCOS

PCOS can present similarly to other endocrine disorders, including: 2

  • Thyroid dysfunction: particularly hypothyroidismΒ can lead to hair loss and menstrual cycle irregularities. However, hirsutism is rare.
  • Congenital adrenal hyperplasia (21-hydroxylase deficiency): this causes cortisol deficiency and may also lead to androgen excess, leading to a clinical picture indistinguishable from that of PCOS.
  • Cushing’s syndrome: excess cortisol production, leading to many features similar to PCOS (e.g. weight gain, acne, hypertension, insulin resistance).
  • Hyperprolactinaemia: can lead to changes in the menstrual cycle. Galactorrhoea is usually present.


Investigations are required to diagnose PCOS (using the Rotterdam criteria) and guide management.Β 

Bedside investigations

Relevant bedside investigations include:

  • Urine hCG: to rule out pregnancy as a cause of menstrual disruption
  • Capillary blood glucose: insulin resistance and type 2 diabetes can be a sequela of PCOS

Laboratory investigations

Relevant laboratory investigations include:2

  • Baseline blood tests: FBC, U&E, CRP
  • Testosterone (total and free): raised in PCOS
  • Sex hormone-binding globulin (SHBG): normal to low in PCOS
  • Testosterone to SHBG ratio: may be raised
  • LH and FSH: LH if often raised, and a LH:FSH ratio >3 can suggest PCOS
  • Oral glucose tolerance test: to assess insulin resistance
  • Lipid screen: to assess cardiovascular risk (PCOS can cause dyslipidaemia)

Other laboratory tests are used to exclude alternative causes and differential diagnoses (e.g TFTs, prolactin, 24h urinary cortisol and 17-hydroxyprogesterone).


The most important imaging for PCOS is a pelvic ultrasound scan, classically showing β‰₯12 follicles (β€œcysts”) on the ovaries and/or increased ovarian volume (>10cm3).1 However, the syndrome can exist without polycystic ovaries.

Transvaginal ultrasound images show multiple follicles in each ovary
Figure 2. Transvaginal ultrasound images show multiple follicles in each ovary.


Diagnosis of PCOS is based on the Rotterdam criteria.4

Two of the following three criteria must be met to make a diagnosis of PCOS:

  1. Imaging: polycystic ovaries on ultrasound
  2. Oligo- or anovulation, or oligo- or amenorrhoea
  3. Hyperandrogenism: clinical and/or biochemical changes


The management of PCOS varies between patients and is tailored to the patient’s preferences and needs.

Β The goals of PCOS management are:

  • Restoration of regular menses to reduce the risk of endometrial hyperplasia
  • Weight loss and preventing insulin resistance/diabetes
  • Restoring fertility
  • Treatment of hirsutism and acne

Lifestyle interventions

Weight loss, regular exercise and diet are some of the most important interventions for PCOS and are associated with the improvement in most symptoms, including:2

  • Improvement in fertility
  • Reduction in cardiovascular risk
  • Reduction in insulin resistance and prevention of diabetes

Shaving, electrolysis, and waxing are useful physical methods for the treatment of hirsutism.

Pharmacological treatment3

There is no single pharmacological treatment which reverses the biochemical abnormalities associated with PCOS.

Medications are used to target specific symptoms and in conjunction with lifestyle changes as detailed above:

  • The combined oral contraceptive pill (COCP) plays a role in restoring regular menstruation, reducing the risk of endometrial hyperplasia, and reducing the effects of hyperandrogenism (such as hirsutism and acne)
  • Specific β€œanti-androgens” pharmacological agents include cyproterone acetate or drospirenone
  • Eflornithine hydrochloride (Vaniqa cream) is useful in reducing unwanted facial hair
  • Metformin is used to reduce the insulin resistance associated with PCOS, and in turn, helps to promote regular menstruation and increases fertility
  • Orlistat is a pancreatic lipase inhibitor which can be used in severe cases to assist with weight loss, should conservative measures fail

For women wishing to conceive, clomiphene has been shown to promote fertility, induce ovulation and increase pregnancy rates. However, there is a risk of multiple pregnancies and ovarian hyperstimulation syndrome.


As an endocrine disorder, PCOS can have wide-ranging systemic complications.4

Infertility is the most common complication, affecting over 75% of women with PCOS.

Women with PCOS also have a higher incidence of pregnancy complications, including spontaneous pregnancy loss. Other pregnancy risks include a higher risk of gestational diabetes and pre-eclampsia.

Oligomenorrhoea and amenorrhoea can increase the risk of endometrial hyperplasia and endometrial cancer. This risk can be reduced using progestogens to induce a withdrawal bleed every 3-4 months.

The endocrine abnormalities of PCOS give patients a higher cardiovascular risk profile, due to metabolic syndrome, insulin resistance, diabetes, hyperlipidaemia, NAFLD and hypertension. Due to the higher risk of T2DM, especially in obese patients, women with PCOS should be screened with an oral glucose tolerance test.

It is important to acknowledge the increased risk of psychological complications. In women with PCOS, there is a higher incidence of mood disorders such as depression, eating disorders, anxiety, and panic disorders.

Key points

  • Polycystic ovary syndrome is the most common endocrine disorder affecting women of childbearing age and is diagnosed using the Rotterdam criteria.
  • The causes of PCOS are unclear but are related to elevated levels of androgens, with or without the presence of β€œcysts” on the ovaries.
  • The most common clinical symptoms include hirsutism, infertility, acne, menstrual disturbances, and weight gain.
  • Clinical signs include hirsutism and signs of metabolic syndrome and insulin resistance such as raised body mass index and acanthosis nigricans.
  • Diagnosis of PCOS is based on the Rotterdam criteria, including ovarian follicles (β€œcysts”) on imaging, menstrual cycle disturbance, and evidence of hyperandrogenism.
  • Management of PCOS includes lifestyle changes such as weight loss and exercise, as well as pharmacological measures such as COCP, clomiphene and metformin.
  • Complications of PCOS can be wide-ranging and systemic: infertility, pregnancy complications, higher cardiovascular risk profile, and psychological disturbances.


Mr Sanjay Rao

Consultant Obstetrician and Gynaecologist

The James Cook University Hospital


Dr Chris Jefferies


  1. BMJ Best Practice. Polycystic ovary syndrome. Last reviewed 9 Feb 2022. Available from: [LINK]
  2. NICE CKS. Polycystic ovary syndrome. Last revised Feb 2022. Available from: [LINK]
  3. Patient UK. Polycystic ovary syndrome. Last edited 16 March 2021. Available from: [LINK]
  4. Royal College of Obstetricians & Gynaecologists. Green-top Guideline No. 33: Long-term Consequences of Polycystic Ovary Syndrome. Published Nov 2017. Available from: [LINK]

Image references

  • Figure 1. Madhero88. Acanthosis nigricans. License: [CC BY-SA]
  • Figure 2. Dr J. Ray Ballinger, Radiopaedia.org, rID: 23638. License: [CC BY-NC-SA]


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