Polycystic Ovarian Syndrome

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder of reproductive-age women, affecting nearly 5%‒10% of women in the age group. Characterized by hyperandrogenism, chronic anovulation leading to oligomenorrhea (or amenorrhea), and metabolic dysfunction, PCOS increases a woman’s risk for infertility, endometrial hyperplasia or carcinoma, and cardiovascular disease. The pathophysiology is incompletely understood but thought to have a multifactorial genetic basis causing altered pulsatile release of gonadotropin-releasing hormone (GnRH), as well as increases in luteinizing hormone (LH), androgens, estrogen, and insulin: The result is chronic anovulation and hirsutism, which define the condition. Diagnosis is one of exclusion; therefore, other causes of abnormal uterine bleeding and hirsutism must be ruled out. Management includes attempting to restore normal ovulation through weight loss, oral contraceptive pills (OCPs), and fertility assistance.

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Epidemiology and Pathophysiology


  • Prevalence: 5%–10% of reproductive-age women in the United States
  • One of the most common causes of:
    • Oligomenorrhea 
    • Secondary amenorrhea 
    • Infertility
    • Hirsutism (abnormal facial and body hair growth)
  • 50%–65% of patients are obese.


The exact mechanisms are unknown, but thought to be complex and include both genetic and environmental factors. Metabolic syndrome and obesity are often, but not always, present and likely contribute to the pathophysiology in some individuals.

  • Polycystic ovarian syndrome (PCOS) includes:
    • ↑ Androgens
    • Chronic anovulation
    • Polycystic-appearing ovaries
    • Metabolic dysfunction (commonly known as metabolic syndrome):
      • Insulin resistance
      • Dyslipidemia
      • Hypertension
      • Associated with obesity
      • ↑ Risk for diabetes and cardiovascular disease
  • Dysfunction in the hypothalamic-pituitary-ovarian axis:
    • ↑ Luteinizing hormone (LH) level:
      • Stimulates testosterone production in ovarian theca cells
      • LH receptors tend to be over-expressed in polycystic ovaries.
      • Cause of ↑ LH: ↑ Estrogen from adipocytes and chronically anovulatory ovarian follicles → alters gonadotropin-releasing hormone (GnRH) pulse → ↑ LH secretion
    • Follicle-stimulating hormone (FSH):
      • FSH stimulation is insufficient for ovulation → abnormal follicle development
      • Evidence of FSH resistance at the follicular level
    • Chronic unopposed estrogen:
      • No ovulation → no progesterone 
      • Results in endometrial proliferation without menses
      • ↑ Risk for endometrial hyperplasia or carcinoma
  • Hyperandrogenism:
    • ↑ LH → ↑ testosterone:
      • ↑ Insulin → sensitizes the ovary to LH
      • Theca cells overexpress steroidogenic enzymes → ↑ testosterone
    • Likely involves a genetic predisposition
    • Androgens secreted primarily from the ovaries and adrenal glands
  • Insulin resistance and obesity:
    • ↑ Insulin → ↑ free testosterone due to:
      • ↑ Androgen production in ovarian theca cells
      • ↓ Hepatic production of sex hormone-binding globulin (SHBG) 
    • Obesity:
      • Adipocytes convert androgens → estrogens → ↓ FSH → worsening ovulatory dysfunction
      • ↑ Insulin resistance → ↑ free testosterone → ↑ hyperandrogenism
      • ↑ Prevalence of metabolic syndrome
      • Unclear whether obesity itself is causative in PCOS

Clinical Presentation

Polycystic ovarian syndrome (PCOS) should be suspected in any reproductive-age female with irregular menses and/or symptoms of hyperandrogenism, especially if obese or presenting with infertility.

Symptoms of hyperandrogenism

  • Hirsutism:
    • Excess terminal body hair
    • Male distribution:
      • Upper lip
      • Chin
      • Periareolar
      • Linea alba
  • Acne vulgaris
  • Male-pattern alopecia
  • Early adrenarche (development of pubic hair, apocrine glands, and sebaceous glands)

Menstrual cycle irregularities

  • Oligomenorrhea (cycle length > 35 days) 
  • Amenorrhea (cycles absent)
  • Symptoms present for 3–6 months or 3 cycle lengths
  • Due to chronic anovulation

Associated conditions

  • Metabolic syndrome:
    • Obesity (especially with ↑ waist:hip ratio)
    • Hypertension
    • Impaired glucose tolerance:
      • Type 2 diabetes mellitus
      • Acanthosis nigricans (marker of insulin resistance)
    • Dyslipidemia
  • Infertility
  • Cardiovascular disease
  • Endometrial hyperplasia and carcinoma
Ancathosis nigricans

Acanthosis nigricans in PCOS:
Thickened, darkened skin can appear on the nape of the neck, axillae, or skinfolds as a sign of high insulin levels from insulin resistance.

Image: “Acanthosis nigricans” by Endocrinology, Diabetology and Metabolic Diseases, Ibn Rochd University Hospital Center of Casablanca, 20360 Casablanca, Morocco. License: CC BY 3.0


Polycystic ovarian syndrome (PCOS) is a diagnosis of exclusion, so other causes of oligo- or amenorrhea and hyperandrogenism must be ruled out. The Rotterdam criteria are commonly used to make the diagnosis once other causes are excluded.

Rotterdam criteria

Diagnosis requires 2 of the 3 following criteria:

  • Clinical and/or biochemical signs of hyperandrogenism
  • Oligo- or anovulation
  • Polycystic ovaries on ultrasound

Physical exam

  • Hirsutism:
    • Male-pattern facial and body hair growth
    • Ferriman-Gallwey score:
      • An objective evaluation of hirsutism
      • Often not helpful as some women remove unwanted hair
    • Consider normal ethnic variations in hair: Mediterranean, Middle Eastern, and South Asian (most hair) > Caucasian and Black > East Asian and Native American (least hair)
  • Pelvic exam:
    • Mild ovarian enlargement
    • Rule out structural causes of abnormal bleeding.
  • Signs of Cushing’s syndrome (alternate diagnosis):
    • Moon face
    • Buffalo hump
    • Abdominal striae
Ferriman-Gallwey hirsutism scoring

Ferriman-Gallwey hirsutism scoring system: a system for objective assessment of the degree of hirsutism

Image by Lecturio.

Laboratory and imaging evaluation

  • Urine human chorionic gonadotropin (HCG): rule out pregnancy
  • Assess other potential causes of abnormal bleeding:
    • Thyroid-stimulating hormone (TSH)
      • ↑ → hypothyroid
      • ↓ → hyperthyroid
    • ↑ Prolactin → hyperprolactinemia
  • Assess for biochemical hyperandrogenism (and other potential causes of hirsutism):
    • Free testosterone: ↑ in PCOS
    • Dehydroepiandrosterone sulfate (DHEA-S): ↑ in certain androgen-secreting adrenal tumors
    • 17-hydroxyprogesterone: ↑ in non-classic congenital adrenal hyperplasia (NCCAH)
  • Assess for metabolic syndrome:
    • 2-hour glucose tolerance test 
    • Fasting lipid panel:
      • ↑ Triglycerides and low-density lipoproteins (LDLs)
      • ↓ High-density lipoproteins (HDLs)
  • Other laboratory tests to consider:
    • Cycle day 3 LH:FSH ratio → often > 2 in PCOS (normal is < 1)
    • 24-hour urinary free cortisol → screen for Cushing’s syndrome
  • Transvaginal ultrasonography:
    • Pearls on a string” (also known as the pearl necklace sign): multiple antral follicles at the periphery of the ovary
    • ↑ Ovarian volume
    • Not required if a woman already meets the Rotterdam criteria
Table: Summary of hormone and lab value changes that may be seen in PCOS
Hormones ↑ in PCOSHormones ↓ in PCOS
  • Androgens
  • LH
  • Estrogen
  • Insulin
  • Prolactin (in some cases)
  • LDL/triglycerides
  • FSH
  • Progesterone
  • SHBG
  • HDL

FSH: follicle-stimulating hormone

HDL: high-density lipoproteins

LDL: low-density lipoproteins

LH: luteinizing hormone

PCOS: polycystic ovarian syndrome

SHBG: sex hormone-binding globulin

Sonograph polycystic ovaries

Ultrasound of a polycystic-appearing ovary:
Note the classic “pearls on a string” around the periphery of the ovary identifying the abnormally developing follicles seen in PCOS. Polycystic appearing ovaries are seen in approximately ⅔ of patients with PCOS and is 1 of the 3 diagnostic Rotterdam criteria.

Image: “Sonographic appearance of polycystic ovaries” by Department of Dermatology, Internal Medicine, Medical University, Graz, Austria. License: CC BY 2.0


General management

  • Weight loss:
    • Goal of 5%–10% weight reduction
    • ↓ Estrogen production in adipocytes → ↓ FSH inhibition by estrogen → resumption of normal ovulation
    • ↓ Risk of metabolic syndrome
  • Regular screening and treatment for:
    • Diabetes
    • Dyslipidemia
    • Hypertension
    • Cardiovascular disease
  • Endometrial protection:
    • Goal is to ↓ risk of endometrial hyperplasia or cancer.
    • Combined oral contraceptive pills (OCPs) → allows regular withdrawal bleeding.
    • Levonorgestrel-containing intrauterine device (IUD) → endometrial suppression
    • Intermittent or continuous progestin therapy

Hirsutism management

  • Mechanical hair removal (e.g., waxing, laser hair removal)
  • Combined OCPs:
    • ↓ LH → ↓ testosterone production in the ovary
    • ↑ SHGB → ↑ binding of testosterone → ↓ free testosterone
    • ↓ DHEA-S in the adrenals
    • ↓ 5-α-reductase activity in the skin
  • Antiandrogens:
    • Spironolactone
    • Finasteride
  • Metformin: 
    • No longer 1st line treatment for any PCOS indication
    • Still considered 1st line in patients with type 2 diabetes mellitus
    • Insulin sensitizing agent: ↓ hepatic glucose production → ↓ insulin → ↓ testosterone 
    • Despite ↓ testosterone, there is limited reduction in hirsutism.
Oral contraception effect on patient with PCOS

Effect of oral contraception on patients with PCOS

Image by Lecturio.

Infertility management

  • Letrozole:
    • Aromatase inhibitor
    • More effective at ovulation induction and safer than clomiphene citrate
    • Not approved by the Food and Drug Administration (FDA) for fertility indications, though considered 1st line by many experts
    • ↓ Estrogen → ↓ inhibition of FSH → ↑ FSH → ↑ follicular development → ovulation
  • Clomiphene citrate: 
    • A selective estrogen receptor modulator (SERM) 
    • FDA approved to treat infertility
    • ↑ FSH → ↑ follicular development → ovulation

Differential Diagnosis

  • Non-classical congenital adrenal hyperplasia (NCCAH): a less severe form of an inherited enzyme deficiency (usually 21-hydroxylase) resulting in decreased production of aldosterone and cortisol. Instead, precursors are shunted down the sex steroid pathways, leading to increased androgens. Patients will develop hirsutism, oligomenorrhea, and infertility. Elevated 17-hydroxyprogesterone is diagnostic for congenital adrenal hyperplasia (CAH), but will be normal in PCOS. Management involves antiandrogens and glucocorticoids. 
  • Cushing’s syndrome: elevated cortisol due to excess adrenocorticotropic hormone (ACTH) secretion, adrenal tumors, or exogenous steroids. Presentation is similar to PCOS with menstrual irregularities and hirsutism, as well as abdominal purple striae, truncal obesity, and moon face. Patients can be screened with a 24-hour urine free cortisol test or a dexamethasone suppression test. Management depends on the cause and includes withdrawal of exogenous steroids, adrenal inhibitors, or surgery for tumors. 
  • Exogenous testosterone exposure: occurs when a man’s testosterone cream is transmitted to a woman through contact exposure. Patients may develop hirsutism; diagnosis is based on history and elevated testosterone levels.
  • Ovarian tumors: sex-cord stromal tumors arising from the theca or granulosa cells within the ovary secreting androgens or estrogens, respectively. Patients may have signs of virilization, irregular menstrual cycles, or abnormal uterine bleeding. Androgen and estrogen levels tend to be more elevated than typically seen in PCOS. Initial treatment is surgical and based on the stage of malignancy.
  • Hypothyroidism: a thyroid hormone deficiency resulting in either oligo- or amenorrhea, which may negatively impact fertility. Effects are likely due to structural similarities between TSH, FSH, and LH, as well as associated decreases in SHBG. Other symptoms include thinning of the hair, dry skin, brittle nails, periorbital edema, constipation, and fatigue. Thyroid-stimulating hormone (TSH) is increased due to low thyroxine. Hypothyroidism is treated with levothyroxine. 
  • Pregnancy: results in amenorrhea, though typically not causing hirsutism symptoms. Pregnancy should be ruled out with a urine pregnancy test when evaluating amenorrhea. Treatment is obstetric care.


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