What is Polycystic Ovary Syndrome (PCOS)?
PCOS is a complex, multisystem endocrine disorder affecting 8-13% of reproductive-aged women, characterized by the presence of at least two of three features: oligo/anovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology on ultrasound. 1, 2
Core Definition and Diagnostic Framework
PCOS represents a heterogeneous condition involving both reproductive and metabolic dysfunction. 3, 4 The disorder is diagnosed using the Rotterdam criteria, which requires meeting at least two of the following three features: 1, 5
- Oligo- or anovulation (menstrual cycle length >35 days suggests chronic anovulation) 1
- Clinical and/or biochemical hyperandrogenism (elevated testosterone, hirsutism, acne, balding) 3, 1
- Polycystic ovarian morphology on ultrasound (≥20 follicles per ovary or ovarian volume >10 mL) 1
Other causes of androgen excess must be excluded, including Cushing's syndrome, androgen-secreting tumors, non-classic congenital adrenal hyperplasia, thyroid disease, and prolactin disorders. 3, 1
Pathophysiology
The underlying mechanisms involve accelerated pulsatile gonadotropin-releasing hormone (GnRH) secretion, insulin resistance, hyperinsulinemia, and downstream metabolic dysregulation. 3 This results in:
- Hypersecretion of luteinizing hormone with LH/FSH ratio >2 3
- Ovarian theca stromal cell hyperactivity producing excess androgens 3
- Hypofunction of the FSH-granulosa cell axis causing follicular arrest and ovarian acyclicity 3
Insulin resistance affects 50-70% of women with PCOS, creating a vicious cycle where hyperandrogenism worsens insulin resistance, which in turn exacerbates hyperandrogenemia. 4, 6
Clinical Manifestations
Reproductive Features
- Irregular menstrual cycles or amenorrhea 7, 6
- Infertility due to anovulation 3, 8
- Hirsutism (excess body hair in male-pattern distribution) 3, 6
- Acne and androgenic alopecia 3, 1
Metabolic Complications
PCOS carries significant cardiometabolic risk that persists beyond reproductive years. 3, 7 Women with PCOS frequently present with:
- Insulin resistance and impaired glucose tolerance (screen all women with 2-hour oral glucose tolerance test) 3, 1
- Type 2 diabetes (increased risk requiring routine screening) 3, 6
- Dyslipidemia including elevated LDL cholesterol, elevated triglycerides, and decreased HDL cholesterol 3, 6
- Obesity and increased waist-hip ratio 3, 1
- Metabolic syndrome occurring more frequently than in the general population 7, 6
- Hypertension and gestational hypertension 3, 6
Psychological Impact
Mental health disorders including depression, anxiety, bipolar disorder, and binge eating disorder occur more frequently in women with PCOS. 6
Important Distinction: PCOS vs. Isolated Polycystic Ovaries
PCOS should not be confused with isolated polycystic ovaries (PCO), which refers to polycystic ovarian morphology on ultrasound without symptoms, pathological signs, or hormonal abnormalities. 3, 2 Isolated polycystic ovaries occur in 17-22% of the general female population, whereas PCOS affects 8-13% of reproductive-aged women. 2, 4 Only some women with polycystic ovaries will develop the full syndrome with chronic oligomenorrhea or amenorrhea associated with increased serum androgen levels. 3
Prevalence and Risk Factors
PCOS affects approximately 1 in 10 women worldwide, with prevalence varying from 6-20% depending on diagnostic criteria used. 4, 8 The condition typically manifests during early to late reproductive age (15-35 years), with most symptoms arising early during puberty. 4, 8
Risk factors include type 1 diabetes, type 2 diabetes, gestational diabetes, and family history of cardiovascular disease and diabetes. 1, 6 Environmental factors such as physical inactivity, unhealthy eating habits, prenatal exposure to excess androgens, and endocrine disruptors may contribute to PCOS development. 4
Long-term Health Implications
Women with PCOS have increased risk of:
- Endometrial cancer due to unopposed estrogen from chronic anovulation 3
- Cardiovascular disease with increased coronary artery calcium scores and carotid intima-media thickness 6
- Persistent metabolic alterations after menopause including continued insulin resistance and hyperandrogenism 7
The hyperandrogenism and metabolic syndrome associated with PCOS persist after the menopausal transition, making lifelong screening and management essential. 7
Common Pitfalls
Avoid using the term "PCOD" (polycystic ovarian disease), as this non-standard terminology can hinder accurate diagnosis, complicate research collaboration, and lead to inadequate disease management. 2 The correct term is PCOS (polycystic ovary syndrome), which accurately reflects the condition's complexity as a multisystem disorder rather than simply an ovarian disease. 2
In adolescents (<17 years), ultrasound should not be used as a first-line diagnostic tool due to poor specificity and high false-positive rates. 1 Diagnosis in this age group should rely more heavily on clinical and biochemical hyperandrogenism plus menstrual irregularity. 1