Polycystic Ovarian Syndrome (PCOS)
Summary
PCOS is a complex heterogeneous metabolic and endocrine disorder affecting 5-10% of women of reproductive age. It is characterised by the triad of Oligo-anovulation, Hyperandrogenism, and Polycystic Ovaries. Crucially, it is not just a gynaecological problem; Insulin Resistance plays a central role in pathogenesis, linking it to Type 2 Diabetes, Obesity, and Cardiovascular disease. Diagnosis is by the Rotterdam Criteria (after excluding other causes). [1,2]
Key Facts
- Insulin Resistance: Present in 70% of obese and 30-40% of lean women with PCOS. High insulin stimulates theca cells to produce androgens and suppresses SHBG production by the liver (increasing free testosterone).
- Fertility: It is the most common cause of anovulatory infertility (75%). However, women still have a large ovarian reserve and respond well to ovulation induction.
- Endometrial Cancer: Unopposed oestrogen (lack of progesterone from anovulation) leads to endometrial proliferation. Women with amenorrhoea have a 3x higher risk of endometrial cancer.
Clinical Pearls
PCO vs PCOS: PCO (Polycystic Ovaries on scan) is not the same as PCOS (The Syndrome). Up to 25% of healthy women have polycystic ovaries on ultrasound but have regular periods and normal hormones. They do not have the syndrome.
Virilisation: Hirsutism (excess hair) is common in PCOS. But Virilisation (deep voice, male pattern balding, clitoromegaly) is NOT. If you see signs of virilisation, suspect an Androgen Secreting Tumour (Ovarian or Adrenal) or Cushing's, and measure testosterone urgently (usually >5 nmol/L).
Weight Loss: Losing just 5-10% of body weight can restore ovulation in 50% of women without any medication. It is the SINGLE most effective intervention.
Demographics
- Prevalence: 1 in 10 women.
- Onset: Usually menarche, but diagnosis often delayed.
- Risk Factors: Obesity, Family History.
Mechanisms
- Hypothalamic-Pituitary: Altered GnRH pulsatility -> High LH / Normal or Low FSH. High LH stimulates ovarian androgen production. Low FSH means follicles don't mature (arrested development -> cysts).
- Insulin Resistance: Hyperinsulinaemia acts as a co-gonadotrophin, increasing androgen synthesis (Theca cells) and decreasing SHBG (Liver).
- Hyperandrogenism: Interferes with follicular development and causes hirsutism.
Rotterdam Criteria (Diagnosis requires 2 of 3)
- Oligo- or Anovulation: Irregular periods (>35 day cycle) or Amenorrhoea.
- Clinical or Biochemical Hyperandrogenism: Hirsutism, Acne, Alopecia OR Raised Testosterone.
- Polycystic Ovaries: ≥12 follicles (2-9mm) or Ovarian Volume >10ml on Ultrasound.
Metabolic
- BMI: Essential.
- Ferriman-Gallwey Score: Quantifies hirsutism (>8 is abnormal).
- Skin: Acne, Acanthosis Nigricans.
- BP: Hypertension risk.
Bloods (Day 2-5 of cycle)
- FSH/LH: LH is often elevated (LH:FSH ratio > 2:1 or 3:1).
- Testosterone: Mildly elevated (1.5 - 4.5 nmol/L). If >5, suspect tumour.
- SHBG: Low.
- Free Androgen Index (FAI): Calculated. Often raised.
- Exclusion: TSH (Hypothyroid), Prolactin (Prolactinoma), 17-OHP (Congenital Adrenal Hyperplasia).
Metabolic Screen
- HbA1c / Oral Glucose Tolerance Test.
- Lipid Profile.
Imaging
- Transvaginal Ultrasound: Gold standard for ovarian morphology. "String of Pearls" appearance.
Management Algorithm
PCOS DIAGNOSIS CONFIRMED
↓
LIFESTYLE MODIFICATION
(Diet, Exercise, Weight Loss target 5-10%)
↓
┌─────────────┼─────────────┐
FERTILITY IRREGULAR HIRSUTISM / ACNE
DESIRED PERIODS (Cosmetic concern)
↓ ↓ ↓
CLOMIFENE / COCP COCP (Dianette)
LETROZOLE (Mirena IUS) TOPICALS (Eflornithine)
↓ ↓ ↓
METFORMIN CYCLICAL PROGEST ANTI-ANDROGENS
(Adjunct) (Medroxyprog) (Spironolactone)
↓ ↓
DRILLING / ENDOMETRIAL
IVF PROTECTION
1. Lifestyle
- Weight Loss: First line for all obese patients. Improves insulin sensitivity, lipid profile, and ovulation rate.
2. Menstrual Regulation (Endometrial Protection)
- Goal: Induce a withdrawal bleed at least every 3-4 months to prevent hyperplasia.
- COCP: First line (e.g. Yasmin/Dianette/Microgynon). Also treats acne/hirsutism.
- Cyclical Progestogens: Medroxyprogesterone 10mg for 14 days every 3 months.
- Mirena IUS: Constant endometrial protection.
3. Hyperandrogenism (Hirsutism)
- COCP: Increases SHBG -> Binds free testosterone.
- Eflornithine Cream: Inhibits hair growth (facial).
- Anti-androgens: Spironolactone / Finasteride (Teratogenic - must use contraception).
4. Fertility (Ovulation Induction)
- Letrozole: Aromatase inhibitor. Now often first line (higher live birth rate than Clomifene).
- Clomifene Citrate: SERM. Induces ovulation. Risk of multiple pregnancy (Twins).
- Laparoscopic Ovarian Drilling: Diathermy to destroy androgen-producing stroma.
- IVF: Last resort.
- Metabolic: Type 2 Diabetes (50% risk), Dyslipidaemia, CVD.
- Oncological: Endometrial Cancer (Endometrioid Adenocarcinoma).
- Sleep: Obstructive Sleep Apnoea.
- Psychological: Depression/Anxiety (Body image).
- Chronic condition.
- Menopause often normalises the hormones, but metabolic risk remains.
- Weight control is the biggest determinant of long-term health.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| PCOS Guideline | ESHRE / ASRM (2018) | International standard. Letrozole is 1st line for fertility. |
| Green-top 33 | RCOG | Long-term consequences of PCOS. |
Landmark Trials
1. PPCOS II Trial (NEJM 2014)
- Comparison: Letrozole vs Clomifene.
- Findings: Letrozole resulted in higher live birth rates and ovulation rates in obese women with PCOS compared to Clomifene.
What is PCOS?
It is a condition where your hormones are slightly out of balance. Your ovaries produce slightly more testosterone (male hormone) than usual, which can stop eggs from being released every month.
What are the "cysts"?
They aren't really cysts (fluid filled sacs needing surgery). They are actually small, immature egg follicles that started to grow but got stuck. They are harmless.
Does it mean I can't have children?
No. It might be harder to get pregnant because you aren't releasing an egg every month, but many women conceive naturally or with the help of simple tablets.
Why does my weight matter?
Fat cells affect hormones. Carrying extra weight makes your body resistant to insulin, which makes the ovaries produce even more testosterone. Losing even a small amount of weight can break this cycle and restart your periods.
Primary Sources
- Teede HJ, et al. Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Hum Reprod. 2018;33:1602-1618.
- Balen AH, et al. The management of anovulatory infertility in women with polycystic ovary syndrome. RCOG Green-top Guideline No. 42. 2014.
- Legro RS, et al. Letrozole versus clomiphene for infertility in the polycystic ovary syndrome. N Engl J Med. 2014.
Common Exam Questions
- Diagnosis: "Criteria name?"
- Answer: Rotterdam Criteria.
- Biochemistry: "Hormone profile?"
- Answer: High LH, High Testosterone, Normal/Low FSH.
- Fertility: "First line drug for ovulation?"
- Answer: Letrozole (or Clomifene - check local guidelines, but Letrozole is ESHRE gold standard).
- Oncology: "Cancer risk?"
- Answer: Endometrial Cancer.
Viva Points
- OHSS Risk: Women with PCOS are at high risk of Ovarian Hyperstimulation Syndrome during IVF because they have so many recruitable follicles. 'Coasting' or lower doses are used.
- Combined Pill Choice: Why Dianette (Co-cyprindiol)? It contains Cyproterone Acetate, which is a potent anti-androgen, effective for acne/hirsutism. Note: increased VTE risk compared to standard pills.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.