The simple idea (no memorising)
Normally the lining lives only inside the womb. In endometriosis, patches of similar tissue settle in the wrong places — on the ovaries, the pouch behind the womb, the ligaments, the pelvic wall. Each month those patches respond to hormones and bleed — but the blood has nowhere to escape. The result:
The classic triad
Think of three D's:
- Dysmenorrhoea — painful periods;
- Dyspareunia — deep pain with sex;
- Difficulty conceiving — infertility.
A tell‑tale detail: the amount of pain doesn't match the amount of disease. Tiny spots can hurt terribly; large ones can be quiet.
The "chocolate cyst"
When endometriosis settles on an ovary, old blood collects into a cyst filled with thick, brown, altered blood — nicknamed a chocolate cyst (an endometrioma). On ultrasound it has a characteristic "ground‑glass" look.
Its cousin: adenomyosis
If the same lining‑type tissue burrows into the muscular wall of the womb itself, that's adenomyosis — think painful, heavy periods and a bulky, tender womb.
| Endometriosis | Adenomyosis | |
|---|---|---|
| Where | outside the womb | inside the womb muscle |
| Classic clue | pain + infertility, chocolate cyst | heavy, painful periods, bulky tender womb |
Why it matters
Endometriosis is common, often under‑recognised, and can quietly steal years of comfort and fertility. Understanding why it hurts (trapped monthly bleeding → inflammation → scarring) makes both the symptoms and the treatments make sense.
Quick check ✅
- What are the three classic symptoms of endometriosis?
- What is a chocolate cyst?
Remember this 🌟
Where we're going next → From misplaced lining to a lump in the muscle — fibroids. Concept 20.