PCOS - Polycystic Ovary Syndrome

What Does PCOS Stand For?

PCOS = Polycystic Ovary Syndrome - a heterogeneous hormonal and metabolic disorder characterized by considerable clinical and biochemical variability among affected individuals.

Note (2026 update): As of May 2026, major institutions like Johns Hopkins and Cleveland Clinic have begun adopting the new name PMOS (Polyendocrine Metabolic Ovarian Syndrome) to better reflect the condition's true nature - since cysts are not always present and the disorder is fundamentally hormonal/metabolic.

Diagnostic Definition (Rotterdam Criteria)

PCOS is diagnosed when a woman has any 2 of the following 3 features (after excluding other causes):

#	Feature	Description
1	Oligo-ovulation or anovulation	Irregular or absent ovulation
2	Hyperandrogenism	Elevated male hormones (clinical or biochemical)
3	Polycystic ovaries on ultrasound	Multiple small follicles on one or both ovaries

Goldman-Cecil Medicine, Vol. 2

How Common Is It?

Affects 6-12% of women of reproductive age worldwide
The most common endocrine abnormality in women of reproductive age
No significant geographic or ethnic differences in prevalence
More than 50% of affected women develop type 2 diabetes by age 40

Signs & Symptoms

Category	Manifestations
Menstrual	Irregular periods, oligomenorrhea, primary or secondary amenorrhea
Androgenic	Hirsutism (excess hair), acne, oily skin, female-pattern hair loss
Metabolic	Insulin resistance, weight gain, obesity
Reproductive	Infertility, anovulation, early miscarriage risk
Cardiovascular	Hypercholesterolemia, risk for later cardiovascular disease

What Causes It?

The exact cause is unknown, but key mechanisms include:

Elevated LH levels - LH tends to be elevated in about 2/3 of cases, driving excess androgen production from the ovaries
Insulin resistance - very commonly present; insulin further stimulates ovarian androgen production
Genetic predisposition - family history of PCOS or type 2 diabetes increases risk
Obesity - worsens the phenotype (though the cause-effect relationship is bidirectional)

Key Long-Term Health Risks

Type 2 diabetes (>50% by age 40)
Gestational diabetes and hypertension in pregnancy
Preeclampsia and preterm birth
Cardiovascular disease (due to hypercholesterolemia and metabolic syndrome)
Endometrial hyperplasia/cancer (from unopposed estrogen due to anovulation)

Treatment Overview

Goal	Treatment
Regulate menstrual cycles	Combined oral contraceptives (first-line if not trying to conceive)
Reduce androgens	OCP + spironolactone or flutamide if inadequate response at 6 months
Endometrial protection	Progestins (medroxyprogesterone, progesterone, or levonorgestrel IUD)
Fertility/ovulation induction	Letrozole (first-line) > clomiphene citrate ± metformin
Metabolic risk	Lifestyle changes + metformin for overweight/obese women
Monitoring	Screen for obesity, hypertension, glycemic control, depression, anxiety at diagnosis and regularly

Harrison's Principles of Internal Medicine, 22E (2025)
Textbook of Family Medicine, 9e

In summary: PCOS is far more than just cysts on the ovaries - it is a complex hormonal and metabolic disorder that can affect menstruation, fertility, appearance, and long-term cardiometabolic health. Diagnosis requires only 2 of the 3 Rotterdam criteria, meaning cysts do not have to be present at all.

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