What is polycystic ovary syndrome (PCOS)?

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What is Polycystic Ovary Syndrome (PCOS)?

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder affecting women of reproductive age worldwide, characterized by a combination of androgen excess, ovulatory dysfunction, and/or polycystic ovarian morphology, with significant impacts on metabolic, reproductive, and psychological health. 1, 2

Definition and Diagnostic Criteria

PCOS is diagnosed when two of the following three criteria are met (after excluding other disorders):

  • Androgen excess (clinical signs like hirsutism, acne, or biochemical hyperandrogenism)
  • Ovulatory dysfunction (irregular menstrual cycles, oligomenorrhea)
  • Polycystic ovaries on ultrasound (≥12 follicles measuring 2-9 mm in diameter and/or ovarian volume >10 mL) 2

Critical exclusions before diagnosis include thyroid disease, hyperprolactinemia, and nonclassic congenital adrenal hyperplasia (via 17-hydroxyprogesterone testing) 2.

Four Recognized Phenotypes

The heterogeneous nature of PCOS manifests in four distinct phenotypes, each with different long-term health implications 3:

  1. Hyperandrogenism + oligo-anovulation + polycystic ovarian morphology
  2. Hyperandrogenism + oligo-anovulation
  3. Hyperandrogenism + polycystic ovarian morphology
  4. Oligo-anovulation + polycystic ovarian morphology

Clinicians should clearly document the specific phenotype when making the diagnosis, as this affects prognosis and management 3.

Clinical Manifestations

Reproductive Features

  • Infertility affects approximately 50% with primary infertility and 25% with secondary infertility, primarily due to anovulation 2
  • Menstrual irregularities with oligomenorrhea or amenorrhea
  • Increased risk of pregnancy complications including gestational diabetes and preterm birth 2

Dermatological Features

  • Hirsutism (present in 65-75% of patients, though lower in Asian populations) 2
  • Acne (prevalence 14-25%, particularly in adolescents) 2
  • Androgenic alopecia (less frequent but highly distressing)
  • Acanthosis nigricans and skin tags 2

Metabolic Complications

PCOS significantly increases risk for:

  • Type 2 diabetes mellitus and impaired glucose tolerance
  • Metabolic syndrome and insulin resistance (affecting 60-80% of patients) 4
  • Cardiovascular disease risk factors including hypertension and dyslipidemia 3
  • Hepatic steatosis (nonalcoholic fatty liver disease) 3

Psychological Impact

  • Depression and anxiety are common, requiring routine screening 2
  • Significant impact on quality of life and emotional wellbeing 1
  • Mood and psychosexual disorders 3

Other Associations

  • Obstructive sleep apnea, particularly in overweight/obese patients 2
  • Endometrial cancer risk due to chronic anovulation, obesity, hyperinsulinism, and diabetes 2

Etiology and Pathophysiology

PCOS is a complex multigenic disorder with strong epigenetic and environmental influences 5. Contributing factors include:

  • Genetic predisposition (highly inherited, polygenic) 3
  • Environmental factors: diet, lifestyle, stress, environmental toxins 6
  • Pathophysiologic abnormalities: altered gonadotropin secretion, impaired folliculogenesis, abnormal steroidogenesis, insulin resistance, and adipose tissue dysfunction 3
  • Gut dysbiosis may play a pathogenic role 6

Prevalence and Impact

PCOS represents the single most common endocrine-metabolic disorder in reproductive-aged women 3. Despite its high prevalence, the condition remains underdiagnosed and misunderstood by many practitioners 3. The syndrome significantly impacts women's well-being and quality of life, often leading to delayed diagnosis and fragmented, symptomatic rather than comprehensive treatment 1.

Special Considerations in Adolescents

Diagnosis in adolescents differs from adults and requires both clinical/biochemical hyperandrogenism AND persistent oligomenorrhea (after exclusion of other pathologies). Anovulatory symptoms and polycystic ovarian morphology alone are not sufficient for diagnosis in adolescents, as these may represent normal pubertal development 2, 7.

Long-term Health Implications

Women with PCOS face increased lifetime risks for:

  • Subfertility and reproductive complications
  • Type 2 diabetes and metabolic syndrome
  • Cardiovascular events and cerebrovascular accidents
  • Endometrial atypia or carcinoma
  • Psychological disorders affecting quality of life 3

The variation in PCOS phenotype and symptoms across affected women often leads to delayed diagnosis, emphasizing the need for heightened clinical awareness and systematic screening 1.

References

3
Research

Polycystic Ovary Syndrome.

Obstetrics and gynecology, 2018

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