Condition Comparison

PCOS vs Endometriosis

Same symptoms, different conditions: here's exactly how to tell them apart.

PCOS

A hormonal disorder where the ovaries produce excess androgens and develop multiple small follicles. Linked to insulin resistance and irregular cycles.

Endometriosis

A condition where tissue similar to the uterine lining grows outside the uterus, on the ovaries, tubes, or pelvis, causing severe pain and scarring.

Side-by-Side Comparison

Feature	PCOS	Endometriosis
Who it affects	Women of reproductive age; common in 20s–30s	Women of reproductive age; often diagnosed in 30s after years of symptoms
Main hormone issue	High LH, high androgens (testosterone), low progesterone	High oestrogen relative to progesterone; inflammatory
Period pattern	Irregular, infrequent or absent	Often regular but extremely painful (dysmenorrhoea)
Pelvic pain	Mild; mainly from ovarian cysts	Severe, especially during periods; pain during sex
Ultrasound finding	12+ small follicles ("string of pearls") in each ovary	May appear normal or show "chocolate cysts" (endometrioma)
Fertility impact	Reduced; anovulation (not releasing eggs regularly)	Reduced; due to scarring, blocked tubes, inflammation
Weight link	Strong link to weight gain and insulin resistance	No direct weight link
Diagnosed by	Pelvic ultrasound + blood hormones (LH, FSH, testosterone, AMH)	Pelvic scan (may miss mild endo) + laparoscopy (gold standard)
Treatment	Lifestyle, metformin, clomiphene, IVF for fertility	Pain relief, hormonal therapy, laparoscopic surgery, IVF

Symptoms They Share

⚠️ Both conditions can cause:

Irregular or painful periods
Difficulty getting pregnant (infertility)
Pelvic pain or discomfort
Bloating and abdominal fullness
Fatigue and low mood

The Key Difference

💡 How to tell them apart

The clearest distinction is when the pain peaks. Endometriosis causes debilitating pain specifically during menstruation and sex, because the misplaced tissue bleeds each month with nowhere to go. PCOS pain is milder and not cycle-specific; the bigger problem is the hormonal disruption (acne, excess hair, weight gain, absent ovulation). Another clue: PCOS is often picked up incidentally on a routine scan or during fertility investigations, while endometriosis patients usually report years of dismissed period pain before diagnosis.

Which Tests Diagnose Each?

🧪 Pelvic Ultrasound (TVS)

The first-line scan for both. In PCOS, the sonographer counts follicles and measures ovarian volume. In endometriosis, they look for chocolate cysts (endometrioma), though mild peritoneal endometriosis can be missed on scan.

🧪 Hormone Blood Tests (LH, FSH, AMH, Testosterone)

Essential for PCOS: a high LH:FSH ratio, elevated testosterone, and high AMH (>3.5 ng/mL) support the diagnosis. These markers are usually normal in endometriosis.

🧪 CA-125 Blood Test

A marker elevated in endometriosis (and other conditions). Not diagnostic alone, but useful alongside scan findings to raise suspicion.

🧪 Laparoscopy (keyhole surgery)

The gold standard for confirming endometriosis: the surgeon directly visualises and biopsies implants. Not needed for PCOS diagnosis.

Frequently Asked Questions

Can you have both PCOS and endometriosis at the same time?

Yes, both conditions are common and can co-exist. A woman may have the hormonal profile of PCOS alongside endometrial implants on her ovaries. This combination makes fertility treatment more complex, so accurate diagnosis is especially important.

My periods are painful and irregular, which is more likely?

Irregular periods with mild pain lean more toward PCOS (anovulation). Regular periods with severe, disabling pain that interfere with daily life lean more toward endometriosis. But only a pelvic ultrasound and hormone tests can point you in the right direction, book an appointment to find out.

Can endometriosis be seen on a normal ultrasound?

A transvaginal scan (TVS) can detect ovarian endometriomas (chocolate cysts) reliably. However, small peritoneal implants, the superficial type, often cannot be seen on ultrasound. A laparoscopy is needed to confirm or exclude mild endometriosis.

Does PCOS go away after pregnancy?

Pregnancy does not cure PCOS. Hormonal patterns may temporarily shift, and some women find cycles more regular after delivery, but the underlying hormonal tendency persists. Ongoing management of insulin resistance and cycle regularity is usually needed.

Not sure which one you have?

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Last updated 16 October 2026.