Polycystic Ovary Syndrome
Summary
PCOS is the most common endocrine disorder in women of reproductive age (10%). It is a complex metabolic syndrome driven primarily by Insulin Resistance, leading to Hyperandrogenism and Anovulation. Diagnosis is based on the Rotterdam Criteria (2 out of 3: Oligo/Anovulation, Hyperandrogenism, Polycystic Ovaries). Management is symptom-oriented: dealing with aesthetic concerns (hirsutism/acne), menstrual irregularity (endometrial protection), and infertility. [1,2]
Clinical Pearls
The "String of Pearls": The classic ultrasound appearance is 12+ small follicles arranged peripherally around a dense stroma. Note: In the era of high-res ultrasound, many "normal" women have polycystic-looking ovaries. PCO morphology alone ≠ PCOS syndrome.
Insulin is the Key: High insulin levels stimulate the Theca cells of the ovary to produce Testosterone. It also suppresses SHBG production by the liver, increasing free testosterone. This is why weight loss (lowering insulin) is the most effective treatment.
Virilisation vs Hirsutism:
- Hirsutism: Excessive terminal hair (PCOS).
- Virilisation: Deep voice, clitoromegaly, balding, increased muscle mass. This is NOT typical of PCOS and suggests an Androgen-Secreting Tumour (Ovary or Adrenal). Check Testosterone levels urgently (>5 nmol/L is a red flag).
Demographics
- Prevalence: 8-13% of women.
- Risk Factors: Obesity, Family History (strong genetic component), Premature Adrenarche.
- Ethnicity: High prevalence in South Asian women (associated with higher insulin resistance).
Mechanism
- Hypothalamic-Pituitary: Increased LH pulse frequency. High LH relative to FSH (LH:FSH > 2:1).
- Ovarian: High LH stimulates Theca cells -> Androgen excess.
- Metabolic: Insulin Resistance -> Hyperinsulinaemia -> Increases ovarian androgen production + Decrease SHBG.
- Result:
- High Androgens -> Hirsutism/Acne.
- Follicular Arrest -> Polycystic appearance + Anovulation.
- Unopposed Oestrogen -> Endometrial Hyperplasia risk.
| Condition | LH | FSH | Testosterone |
|---|---|---|---|
| PCOS | High/Normal | Normal | Mild High |
| Hypothalamic Amenorrhoea | Low | Low | Normal |
| Premature Ovarian Insufficiency | High | Very High | Normal |
| Adrenal Tumour/CAH | Normal | Normal | Very High (>5) |
| Prolactinoma | Normal | Normal | Normal (High Prolactin) |
Rotterdam Criteria (Need 2 of 3)
- Oligo- or Anovulation: Irregular periods (>35 day cycle) or Amenorrhoea.
- Hyperandrogenism:
- Clinical: Hirsutism (Ferriman-Gallwey score >8), Acne, Alopecia.
- Biochemical: Raised Free Androgen Index (FAI) / Testosterone.
- Polycystic Ovaries: Ultrasound >20 follicles per ovary OR ovarian volume >10ml. (Ideally transvaginal).
Associated Features
Endocrine Profile (Day 2-5 of cycle)
- FSH/LH: LH often elevated.
- Testosterone/SHBG: Calculate Free Androgen Index (FAI). T usually 1.5-4 nmol/L.
- Prolactin / TSH: Exclude other causes of amenorrhoea.
- 17-OH Progesterone: Exclude Late Onset Congenital Adrenal Hyperplasia (LOCAH).
Metabolic Screen
- HbA1c: Screen for Diabetes/Prediabetes.
- Lipid Profile: Dyslipidaemia common.
Imaging
- Transvaginal Ultrasound: "String of pearls" appearance. Note: Not required for diagnosis if Criteria 1 & 2 are met.
Management Algorithm
DIAGNOSED PCOS
↓
LIFESTYLE MODIFICATION (First Line)
• Weight Loss (5-10%)
• Exercise / Diet
↓
IDENTIFY PRIMARY GOAL
┌─────────┼─────────┐
FERTILITY PERIODS HIRSUTISM
↓ ↓ ↓
Ovulation COCP COCP (Dianette)
Induction (Mirena) Topical Eflornithine
Laser
1. Menstrual Regulation (Endometrial Protection)
- Women with amenorrhoea are at risk of Endometrial Hyperplasia/Cancer due to unopposed oestrogen.
- Combined Oral Contraceptive (COCP): Induces withdrawal bleed.
- Mirena IUS: Protects endometrium.
- Cyclical Progestogens: (e.g. Medroxyprogesterone 10mg for 10 days every 3 months) to induce bleed.
2. Hyperandrogenism (Hirsutism/Acne)
- COCP: Increases SHBG, binding free testosterone. (Dianette/Yasmin are anti-androgenic).
- Topical Eflornithine: Facial cream (Vaniqua).
- Laser/Electrolysis.
- Anti-androgens (Specialist): Spironolactone / Finasteride (Teratogenic - must use contraception).
3. Fertility
- Weight Loss: Restores spontaneous ovulation in many.
- Letrozole: Aromatase inhibitor. Now First Line for ovulation induction.
- Clomifene Citrate: SERM. Older first line. Risk of multiples.
- Metformin: Improves insulin sensitivity. Adjuvant.
- IVF: Final option.
- Metabolic Syndrome: T2DM (Increased risk x4), Hypertension, CVD.
- Endometrial Cancer: Risk increased due to unopposed oestrogen.
- Psychological: Depression/Anxiety regarding body image/fertility.
- Sleep Apnoea.
- Chronic: Lifelong condition, but symptoms often improve after menopause (androgen levels drop).
- Fertility: Excellent prognosis with assistance. Most women with PCOS will eventually have children.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| PCOS Management | ESHRE / Teede (2023) | International Evidence-based Guideline. Letrozole is 1st line for fertility. |
| Fertility | RCOG / NICE | Protocols for ovulation induction. |
Landmark Evidence
1. Teede et al (2023)
- The comprehensive international guideline updating the Rotterdam criteria (including AMH as a potential alternative to Ultrasound) and establishing Letrozole > Clomifene.
What is PCOS?
It is a very common hormonal condition where the ovaries are slightly "sleepy" and don't release an egg every month. Instead, the eggs form tiny fluid-filled sacs (cysts). It also causes slightly higher levels of male-type hormones.
Why do I have it?
It is strongly linked to how your body handles insulin (the sugar-control hormone). If you are resistant to insulin, your levels go up, which tells the ovaries to make more testosterone. This stops the eggs from releasing.
Will I be able to have children?
Yes. Most women with PCOS get pregnant. You might need a little help (tablets like Letrozole) to kick-start the ovaries to release an egg, but the machinery works perfectly well.
Do I need to treat it if I don't want a baby now?
Yes, it is important to have at least 3-4 periods a year to keep the lining of the womb thin and healthy. If you go for years without a period, the lining can grow too thick and turn into cancer. We usually use the Pill or a Coil to prevent this.
Primary Sources
- Teede HJ, et al. Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Fertil Steril. 2023.
- Balen AH, et al. Ultrasound assessment of the polycystic ovary: international consensus definitions. Hum Reprod Update. 2003.
Common Exam Questions
- Diagnosis: "Criteria for PCOS?"
- Answer: Rotterdam (2 out of 3).
- Oncology: "Cancer risk in PCOS?"
- Answer: Endometrial Cancer (Unopposed Oestrogen).
- Fertility: "First line drug for ovulation?"
- Answer: Letrozole (replaced Clomifene).
- Endocrinology: "LH:FSH Ratio?"
- Answer: Typically > 2:1 (High LH).
Viva Points
- Why Letrozole?: It has a higher live birth rate and lower multiple pregnancy rate compared to Clomifene.
- Unopposed Oestrogen: Explain the concept. Without ovulation, there is no Corpus Luteum. No Corpus Luteum = No Progesterone. Progesterone is what "thins" the lining. Without it, Oestrogen builds the lining up indefinitely -> Hyperplasia -> Cancer.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.