Endometriosis vs Fibroids: How To Tell the Difference

⚕️ Medical note: This article is for informational purposes only and does not constitute medical advice. No lifestyle approach has been proven to shrink or eliminate uterine fibroids. Please consult a qualified gynecologist or healthcare provider for diagnosis and treatment options. If you are experiencing severe symptoms, seek prompt medical care.

Endometriosis and fibroids are two distinct conditions that are frequently confused — partly because they share several symptoms and partly because both are under-discussed in mainstream medicine. This article explains the key differences in plain language.

What They Are

Fibroids are benign tumours (non-cancerous growths) made of uterine smooth muscle tissue. They grow within or attached to the uterus. They are not endometrial tissue and do not spread outside the uterus in the way endometriosis does.

Endometriosis is a condition where tissue similar to the endometrial lining grows outside the uterus — on the ovaries, fallopian tubes, bladder, bowel, or pelvic peritoneum. This tissue responds to hormonal cycles, bleeding internally with each period, causing inflammation, scarring, and adhesions (internal scar tissue binding organs together).

A woman can have both conditions simultaneously — they are not mutually exclusive and the hormonal environment associated with estrogen dominance is relevant to both.

How the Symptoms Differ

Symptom	Fibroids	Endometriosis
Heavy bleeding	Common, often very heavy	Can be heavy but variable
Period pain	Often severe	Often severe; can be debilitating
Between-period pain	Pressure/fullness; less acute	Often present; can be chronic
Pain during sex	Common (deep pelvic)	Very common (deep pelvic)
Abdominal swelling	Common with large fibroids	Less typical
Bowel symptoms	Constipation (posterior fibroids)	Bowel pain/bleeding possible
Fertility impact	Variable by type/location	Significant, especially with ovarian involvement

How They Are Diagnosed

Fibroids are typically diagnosed by ultrasound — they are visible on standard pelvic ultrasound. See our guide on how fibroids are diagnosed.

Endometriosis is more difficult to diagnose. Ultrasound can detect some endometriosis (particularly ovarian endometriomas — “chocolate cysts”) but misses most superficial and peritoneal disease. MRI is more informative. Definitive diagnosis requires laparoscopy (keyhole surgery) with direct visualisation and ideally biopsy. This is why endometriosis is typically diagnosed 7–10 years after symptoms begin.

If You Suspect Both

If your fibroid symptoms include features more typical of endometriosis — particularly severe chronic pelvic pain between periods, bowel symptoms correlated with your cycle, or very severe dyspareunia disproportionate to your fibroid size — ask specifically whether endometriosis should be investigated alongside fibroids. The two conditions are managed differently and having one does not exclude the other.