What is Polycystic Ovary Syndrome (PCOS)?
PCOS is a common endocrine disorder affecting 8-13% of reproductive-aged women, characterized by a combination of reproductive dysfunction (irregular ovulation), hormonal imbalance (excess androgens), and metabolic disturbances that significantly impact fertility, cardiovascular health, and quality of life. 1, 2
Core Definition and Prevalence
PCOS represents a complex, multisystem endocrine disorder that extends beyond simple ovarian dysfunction. 2 The syndrome affects approximately 8-13% of women during their reproductive years, making it the most common endocrine disorder in this population. 1, 3, 4 This prevalence is notably higher than isolated polycystic ovaries (17-22% of women), which represents ovarian morphology changes without the full syndrome. 1, 2
Diagnostic Criteria (Rotterdam Criteria)
The diagnosis requires at least two of the following three features, after excluding other disorders: 5, 2, 3
- Oligo- or anovulation (irregular or absent menstrual cycles, typically >35 days apart) 5
- Clinical and/or biochemical hyperandrogenism (excess male hormones manifesting as hirsutism, acne, male-pattern baldness, or elevated testosterone levels) 5, 2
- Polycystic ovarian morphology on ultrasound (≥20 follicles per ovary or ovarian volume >10 mL) 5
Important diagnostic caveat: Ultrasound should not be used as a first-line diagnostic tool in adolescents under 17 years due to poor specificity, as multi-follicular ovaries are physiologically normal during this developmental period. 5, 1 In adolescents, diagnosis relies primarily on hyperandrogenism plus menstrual irregularity. 5, 3
Pathophysiology
The underlying mechanisms involve multiple interconnected systems: 1, 4
- Accelerated GnRH pulsatility leading to excessive luteinizing hormone (LH) secretion and elevated LH/FSH ratios (typically >2) 1
- Ovarian dysfunction with theca cell hyperactivity producing excess androgens and follicular arrest preventing normal ovulation 1
- Insulin resistance and hyperinsulinemia affecting 50-70% of women with PCOS, which further stimulates ovarian androgen production 4, 6
- Chronic low-grade inflammation and oxidative stress contributing to metabolic complications 4
Clinical Manifestations
Reproductive Features
- Irregular menstrual cycles or amenorrhea (absent periods) 6
- Infertility due to chronic anovulation 6, 7
- Increased risk of endometrial cancer from unopposed estrogen exposure 1
Hyperandrogenic Features
- Hirsutism (excess body/facial hair in male distribution patterns) 1, 5
- Acne and oily skin 1, 5
- Male-pattern baldness or hair thinning 1, 5
- Clitoromegaly in severe cases 1
Metabolic Features
- Insulin resistance with elevated fasting glucose/insulin ratios 1
- Obesity, particularly central/abdominal distribution 1, 6
- Acanthosis nigricans (dark, velvety skin patches indicating insulin resistance) 1
- Type 2 diabetes risk (requires screening in all PCOS patients) 1, 5
- Dyslipidemia with elevated LDL cholesterol, triglycerides, and reduced HDL cholesterol 1, 6
Cardiovascular Risk
Women with PCOS demonstrate multiple cardiovascular risk factors including hypertension, dyslipidemia, increased coronary artery calcium scores, and increased carotid intima-media thickness. 1, 6, 8 The syndrome is associated with endothelial dysfunction and subclinical atherosclerosis. 8
Psychological Impact
Depression, anxiety, bipolar disorder, and binge eating disorder occur more frequently in women with PCOS, significantly affecting quality of life. 6, 7
Critical Distinctions
PCOS must be distinguished from isolated polycystic ovaries (PCO), which refers only to the ultrasound appearance of multiple small follicles without hormonal abnormalities or symptoms. 1, 2 Approximately 17-22% of women have PCO on ultrasound but do not meet criteria for PCOS. 1, 2
Differential Diagnosis Requirements
Before confirming PCOS, exclude these conditions: 1, 5
- Cushing's syndrome (look for buffalo hump, moon facies, hypertension, abdominal striae) 1, 5
- Androgen-secreting tumors (rapid onset, severe hyperandrogenism with testosterone >5 nmol/L) 1, 5
- Non-classic congenital adrenal hyperplasia (elevated DHEAS levels) 1, 5
- Thyroid disease and hyperprolactinemia (check TSH and prolactin levels) 1, 5
- Acromegaly (in presence of coarse features and enlargement) 1, 5
Associated Conditions
PCOS prevalence is notably elevated in women with epilepsy (10-25% even without antiepileptic drugs), suggesting shared pathophysiological mechanisms involving altered GnRH pulsatility. 1 The syndrome is also associated with uterine fibroids, endometriosis, and increased risk of gestational hypertension. 1
Long-term Health Implications
Beyond reproductive concerns, PCOS represents a lifelong metabolic disorder requiring ongoing surveillance for: 6, 7, 8
- Type 2 diabetes mellitus (screen all patients with fasting glucose and 2-hour oral glucose tolerance test) 1, 5
- Cardiovascular disease (monitor lipid profiles, blood pressure, and cardiovascular risk factors) 1, 5, 8
- Metabolic-associated fatty liver disease 1, 4
- Obstructive sleep apnea 8
- Endometrial hyperplasia and cancer risk from chronic anovulation 1