🩸 Endometriosis Biomarker & MRI Diagnosis Simulator

Clinical Suspicion of Endometriosis

Chronic pelvic pain raises suspicion long before any scan is ordered.

• 7–10 yrs: Average diagnostic delay (symptom onset to diagnosis)
• ~10%: Reproductive-age prevalence (women and girls globally)
• ~80%: Dysmenorrhea reported (of endometriosis patients)
• Non-invasive: First-line workup (no surgery required upfront)

Typical symptom pattern

Cyclical pelvic pain, painful periods, and deep pain during sex.

Why non-invasive workup first

Laparoscopy is definitive but invasive, so imaging and labs come first.

Guidelines now favor imaging-based diagnosis over routine surgery.

Building the diagnostic picture

History, exam, biomarker, and imaging findings are combined stepwise.

CA-125 — A Supportive, Not Confirmatory, Marker

CA-125 rises with endometriosis but is far from diagnostic on its own.

• <35 U/mL: Normal CA-125 cutoff (standard clinical threshold)
• ~50–60%: Sensitivity for endometriosis (moderate at best)
• ~70–90%: Specificity (raised by many conditions)
• Severity: Correlates with (higher in advanced disease)

What CA-125 measures

A glycoprotein shed by irritated pelvic and ovarian tissue.

Why it cannot confirm disease

Fibroids, pregnancy, and infection also raise CA-125.

CA-125 screens and tracks disease — it never replaces imaging.

Clinical role today

Used to flag severe disease and monitor treatment response.

Transvaginal Ultrasound (TVUS)

A high-frequency probe images ovaries and deep pelvic structures directly.

• ~90%: Endometrioma sensitivity (ground-glass ovarian cyst)
• ~79%: Deep infiltrating lesion sensitivity (operator-dependent)
• Lower: Cost vs MRI (wider first-line access)
• 15–20 min: Typical exam time (outpatient procedure)

What TVUS detects well

Ovarian endometriomas show as ground-glass cystic lesions.

Its limits

Deep lesions behind the uterus are easy to miss on ultrasound.

A negative TVUS never rules out deep infiltrating disease.

When MRI is added next

Suspected deep disease or surgical planning prompts MRI.

The "Kissing Ovaries" Sign

Adhesions pull both ovaries into midline contact behind the uterus.

• Very high: Sign specificity (for pelvic adhesions)
• Fibrosis: Underlying cause (from chronic inflammation)
• Frozen pelvis: Associated finding (obliterated cul-de-sac)
• T2-weighted: MRI sequence used (best soft-tissue contrast)

What the sign looks like

Both ovaries touch or overlap in the midline pelvis.

Why it forms

Chronic adhesions fuse the ovaries behind a retroverted uterus.

Kissing ovaries strongly predict a surgically frozen pelvis.

Surgical planning value

It warns surgeons of dense adhesions before laparoscopy.

MRI Rectovaginal Nodule

The deepest, most symptomatic endometriosis lesion becomes visible.

• ~90%: MRI sensitivity for DIE (deep infiltrating endometriosis)
• Rectovaginal septum: Common nodule site (between vagina and rectum)
• Dyschezia: Linked symptom (painful bowel movements)
• Highest: Diagnostic confidence (combined biomarker + imaging)

What the nodule represents

Fibrotic endometrial tissue infiltrating the rectovaginal septum.

Why MRI succeeds here

Superior soft-tissue contrast reveals lesions ultrasound misses.

MRI plus CA-125 plus TVUS gives the strongest non-surgical diagnosis.

From diagnosis to treatment

Confirmed mapping guides medical therapy or targeted surgery.