🩸 Endometriosis Pain Mechanism & Management Simulator

Ectopic Endometrial Lesions Trigger Local Inflammation

Misplaced tissue outside the uterus ignites a chronic immune response.

• ~10%: Prevalence (reproductive-age women)
• ~7 yrs: Diagnostic delay (average time to diagnosis)
• Ovary, peritoneum: Common sites (pelvic implants)
• 10×: Peak macrophages (vs normal peritoneal fluid)

What are ectopic implants

Endometrial-like tissue grows outside the uterine cavity.

Local immune reaction

Macrophages and mast cells swarm and release cytokines.

Prostaglandin surge

Lesions overproduce PGE2, fueling pain and lesion growth.

Neurogenic Inflammation Sensitizes Pelvic Nerves

Inflammatory mediators lower the firing threshold of local nerves.

• ↑ 2-3×: Nerve fiber density (in lesion-adjacent tissue)
• NGF: Key mediator (nerve growth factor)
• Histamine: Mast cell role (sensitizes nociceptors)
• C & Aδ: Fiber types affected (pain-conducting fibers)

Mediator cascade

Cytokines, NGF, and prostaglandins bathe nearby nerve endings.

Nerve fiber sprouting

New nerve fibers grow directly into lesion tissue.

Lowered pain threshold

Sensitized nociceptors fire from normally painless stimuli.

Sensitized Nerves Fire More Readily

Chronic peripheral input keeps pain pathways continuously active.

• Weeks: Allodynia onset (after sensitization begins)
• ↑ markedly: Signal frequency (in sensitized fibers)
• >6 mo: Pain chronicity (defines chronic pelvic pain)
• ~80%: Dysmenorrhea link (of patients affected)

Peripheral sensitization

Nociceptors lower their activation threshold repeatedly.

Signal amplification

Repeated firing strengthens the pain pathway itself.

Chronic pain onset

Pain persists even between menstrual cycles.

Spinal Cord Neurons Become Hyperexcitable

Prolonged input rewires spinal pain-processing circuits.

• NMDA: Wind-up phenomenon (receptor-driven amplification)
• Widened: Pain spread (beyond pelvic dermatome)
• Positive: Duration correlation (longer disease, more sensitized)
• IBS, IC: Comorbid conditions (often co-occur)

Dorsal horn changes

Spinal neurons amplify incoming pain signals.

Wind-up and NMDA

Repeated firing recruits NMDA receptors, boosting response.

Widespread pain

Pain can spread beyond the original pelvic site.

Targeting Multiple Pain Pathways at Once

NSAIDs, progestins, and adjuncts each interrupt a different step.

• COX-1/2: NSAID target (blocks prostaglandin synthesis)
• Lesion activity: Progestin target (suppresses growth & bleeding)
• Highest: Combined efficacy (multi-pathway coverage)
• PT, neuromodulators: Adjunct options (address central sensitization)

NSAIDs block prostaglandins

COX inhibition reduces peripheral inflammatory pain.

Progestins suppress lesions

Hormonal therapy shrinks lesion activity at the source.

Combined multimodal care

Layered therapy addresses peripheral and central pain.