Endometriosis

Reading File

Finding Sources

Searching Images

endometriosis pelvis laparoscopy lesions

Reading File

Loading Image

Here is a comprehensive overview of endometriosis based on authoritative medical textbooks.

Endometriosis

Definition

Endometriosis is defined by the presence of endometrial glands and stroma in locations outside the uterus. It affects approximately 10% of women in their reproductive years and nearly 50% of women with infertility.

Types

There are three recognized forms:

Superficial peritoneal endometriosis — implants on the peritoneal surface
Ovarian endometriosis — forms endometriomas ("chocolate cysts")
Deep infiltrating endometriosis (DIE) — the form with the highest risk of malignant transformation

Pathogenesis

The exact mechanism remains elusive, but four leading theories exist:

Theory	Mechanism
Regurgitation (Sampson's)	Retrograde menstrual flow implants endometrial tissue at ectopic pelvic sites via the fallopian tubes
Benign metastasis	Endometrial tissue spreads to distant sites (bone, lung, brain) via blood/lymphatics
Metaplastic	Coelomic epithelium (mesothelium) undergoes metaplasia into endometrial tissue — explains cases in men or pre-menarchal girls
Stem/progenitor cell	Bone marrow stem cells differentiate into endometrial tissue at ectopic sites

Why implants persist — molecular mechanisms

Pathogenesis of endometriosis — retrograde menstruation leads to implants that produce aromatase, PGE2, angiogenic factors, and activate macrophages (COX-2), creating a self-sustaining estrogen-rich microenvironment

Endometriotic implants are not simply "misplaced" endometrium — they are metabolically distinct:

Aromatase overexpression → local estrogen production from androgens
Elevated PGE₂, VEGF, and MMPs (partly from recruited macrophages) → promotes inflammation and angiogenesis
This creates a self-sustaining estrogen-rich microenvironment that favors implant survival

Morphology

Grossly: red-brown nodules on serosal surfaces (1 mm to 1–2 cm), representing sites of cyclic bleeding
Extensive disease → fibrous adhesions between tubes, ovaries, and surrounding structures; obliteration of the pouch of Douglas
Endometriomas ("chocolate cysts"): cystic ovarian masses (3–5 cm) filled with old brown blood
Microscopically: diagnosis requires both endometrial glands AND stroma at ectopic sites

Laparoscopic appearance

Bilateral ovarian endometriosis with dense pelvic adhesions — laparoscopic view showing endometriotic lesions and fibrous bands tethering pelvic structures

Common Sites of Involvement

Pelvic (most frequent): ovaries, pouch of Douglas, uterosacral ligaments, fallopian tubes
Gastrointestinal: 12–37% of cases; sigmoid colon and small bowel most common; caecum also affected
- Serosal implants invade the muscularis propria → fibrosis, wall contraction, mass effect
- Mucosal surface remains intact but rectal bleeding may occur
Extra-pelvic (rare): periumbilical tissue, laparotomy scars, lung, pleura, bone, brain

Clinical Features

Feature	Details
Dysmenorrhea	Severe; hallmark symptom due to intrapelvic bleeding
Dyspareunia	Deep pain during intercourse
Chronic pelvic pain	Persistent; from adhesions and peritoneal inflammation
Menstrual irregularities	Common
Infertility	Presenting complaint in 30–40% of patients

Diagnosis

Clinical suspicion based on symptoms (especially the triad of dysmenorrhea, dyspareunia, pelvic pain)
Laparoscopy — gold standard; allows direct visualization and biopsy of implants
MRI — preferred cross-sectional imaging; demonstrates low-signal fibrotic plaques, rectovaginal nodules, and pouch of Douglas obliteration on T2-weighted sequences
Transvaginal ultrasound — can identify endometriomas and, with expertise, superficial implants ("honeycomb" appearance with pocket/hat signs on peritoneal surfaces)

MRI of deep infiltrating endometriosis

Sagittal T2 MRI showing low-signal nodularity obliterating the pouch of Douglas with tethering of the rectal wall to a deep rectovaginal endometriotic nodule

Treatment

Category	Options
Medical	NSAIDs/COX-2 inhibitors (pain), aromatase inhibitors (reduce local estrogen), GnRH agonists/antagonists, combined oral contraceptives, progestins
Surgical	Laparoscopic excision or ablation of implants; adhesiolysis; cystectomy for endometriomas; nerve-sparing deep excision for DIE

Malignant Transformation

Although uncommon, malignancy can develop within endometriotic tissue. Risk is mainly confined to deep infiltrating endometriosis. Endometriosis-associated ovarian cancers are primarily clear cell and endometrioid histotypes.

Sources: Robbins & Kumar Basic Pathology; Grainger & Allison's Diagnostic Radiology

This is a shared conversation. Sign in to Orris to start your own chat.