🔑 Key Learning

  • Infertility affects 1 in 8 couples in the UK.
  • The most common cause in women is ovulatory dysfunction; in men, sperm abnormalities.
  • Initial investigations begin after 1 year of regular UPSI, or after 6 months if age > 36 or known risk factors.
  • Mid-luteal progesterone confirms ovulation and should be timed to the cycle length.

📚 Background

Infertility is commonly defined as the failure to conceive after one to two years of regular unprotected sexual intercourse (UPSI). Subfertility affects approximately 1 in 8 couples in the UK.

🧠 Causes of Infertility

Ovulatory disorders (most common cause in women)

  • Hypogonadotropic hypogonadism:
    • Stress, excessive exercise, eating disorders (hypothalamic amenorrhoea)
    • Kallmann syndrome (anosmia is a common exam clue)
  • PCOS
  • Hyperprolactinaemia (e.g. prolactinoma, drug-induced)
  • Ovarian failure (suggested by raised FSH/LH, low oestradiol)
  • Other: thyroid dysfunction, Cushing’s syndrome, CAH, chronic illness

Tubal disease

  • Pelvic inflammatory disease (PID)
  • Endometriosis
  • Previous surgery or ectopic pregnancy

Male infertility

  • Primary spermatogenic failure (trauma, torsion, dysgenesis, tumour)
  • Genetic causes (e.g. Klinefelter’s syndrome, Kallmann syndrome)
  • Obstruction (e.g. vas deferens, ejaculatory duct)
  • Varicocele
  • Drugs (e.g. sulfasalazine, anabolic steroids)

🧪 Investigations

When to start investigations

  • After 12 months of regular UPSI (2–3 times/week)
  • Earlier if:
    • Female age > 36 - begin after 6 months
    • Oligo-/amenorrhoea
    • Known history of PID, endometriosis, or male factor risk

Female investigations

  • Mid-luteal phase progesterone (confirms ovulation)
    • 7-days before the expected period:
      • Day 21 for 28-day cycle, day 28 for 35-day cycle
  • Gonadotrophins (FSH/LH) on day 2–4:
    • Low: hypothalamic cause
    • High: ovarian failure
  • Prolactin and TFTs
  • STI screen
  • Tubal patency test
    • If no history of comorbidities which may affect tubal patency (PID/endometriosis) - hysterosalpingogram 
    • If there is a history - diagnostic laparoscopy and dye - assess tubes and pelvis simultaneously 

Male investigations

  • Semen analysis
  • STI screen

💊 Management Options

  • Medical: clomifene, gonadotrophins
  • Surgical: management of tubal disease, endometriosis
  • Assisted conception: IUI, IVF, ICSI

⚠️ Ovarian Hyperstimulation Syndrome (OHSS)

A rare but serious complication of fertility treatment (e.g. clomifene, IVF).

Clinical Features

  • Abdominal pain and bloating
  • Nausea, vomiting
  • Oliguria
  • Ascites
  • Peripheral oedema
  • Thromboembolism
  • Pleural effusion/hydrothorax

📝 Exam Clues & Clinchers

  • Begin investigations after 1 year (6-months if age 36+)
  • Mid-luteal progesterone is the key test to confirm ovulation and should be performed in all women
  • Anosmia + amenorrhoea → think Kallmann syndrome
  • PCOS: increased LH:FSH ratio and oligomenorrhoea, acne, obesity, hirsutism 
  • OHSS → IVF patient + bloating, ascites, oliguria

🔗 Useful Links and References