• Clinical science

Polycystic ovary syndrome (Stein–Leventhal syndrome…)


Polycystic ovary syndrome (PCOS) is a heterogeneous disorder characterized by hyperandrogenism, oligoovulation/anovulation, and/or the presence of polycystic ovaries. The diagnosis of PCOS is made following exclusion of disorders that may present with a similar clinical picture (e.g., congenital adrenal hyperplasia), most commonly by hormone analysis. Up to 50% of PCOS patients have metabolic syndrome, which is associated with obesity, insulin resistance, hypercholesterolemia, and an increased risk for endometrial cancer. PCOS primarily manifests with hirsutism, acne, and virilization. Diagnostic methods include a pelvic exam, blood tests for specific hormones, and ultrasound. Management consists of weight loss via lifestyle changes, and oral contraception pills are indicated in women who do not wish to conceive. The aim of treatment in women who desire to conceive is to normalize ovarian function and stimulate follicular growth (e.g., with clomiphene).


  • Frequency: 6–10% of women in their reproductive years


Epidemiological data refers to the US, unless otherwise specified.


Hyperandrogenism in women is most commonly caused by PCOS!References:[1][2][3]

Clinical features

Voice change may occur in severe forms of PCOS. However, it typically suggests a different underlying cause of hyperandrogenism!



Diagnostic criteria

According to the American Association of Clinical Endocrinologists, at least two of three of the criteria below are required for diagnosis of PCOS after excluding other causes of irregular bleeding and elevated androgen levels.

Diagnosis of PCOS is possible without the presence of ovarian cysts!
Rule out any other causes of hyperandrogenism and anovulation (see “Differential diagnoses” below).

Blood hormone levels

A clinical picture of hyperandrogenism overrules any normal hormone levels and can fulfill a diagnostic criterium of PCOS!

Evaluate for metabolic disease

Transvaginal ultrasound

  • Enlarged ovaries with numerous anechoic cysts (polycystic ovaries)
  • "String of pearls” appearance



The histological characteristics of PCOS are:


Differential diagnoses

All conditions that are associated with menstrual cycle changes and signs of virilization should be ruled out before diagnosing PCOS:

The differential diagnoses listed here are not exhaustive.


The therapeutic approach in PCOS is broadly based on whether or not the patient is seeking treatment for infertility.




We list the most important complications. The selection is not exhaustive.