When Pain Tells a Complex Story: Ruptured Endometriotic Cyst vs Appendiceal Pathology — A Diagnostic Journey

 Hello Glias !

Acute lower abdominal pain in a reproductive-age woman often triggers suspicion of appendicitis. But sometimes, the real pathology lies within the ovaries — and can closely mimic gastrointestinal emergencies.

Here’s a recent case that emphasizes the importance of radiologic precision and multimodality imaging in diagnosing ruptured endometriotic cysts.

A woman presented with:

• Severe lower abdominal tenderness

• Pain radiating to the right lower rib

• Guarding and rebound suggesting acute abdomen

Her ultrasound was challenging:

• Appendix not visualized

• Pelvic free fluid detected

• No tubo-ovarian abscess (TOA) appearance

• Previous history of hemorrhagic cyst under resolution

Differentials included:
✅ Ruptured hemorrhagic ovarian cyst
✅ Peritonitis from ruptured appendicitis

Given diagnostic uncertainty → Cross-sectional imaging warranted.

CT & MRI — Key Turning Point in Diagnosis

CT demonstrated:

• Marked omental and pelvic fat stranding

• Loculated pelvic fluid rather than diffuse ascites

• Complex right multilocular ovarian cyst

MRI & TVS revealed:

• Variable-age blood products within cyst

• Absent sliding sign → pelvic adhesions

• Deep infiltrating endometriosis at torus uterinus

→ Collectively pointing toward ruptured ovarian endometriotic cyst.

How Literature Supports Our Findings

| Feature                                        | Seen in our case? | Supported by article?                                   |

| ------------------------------------      | :---------------: | ------------------------------------------------------- |

| Multiloculated ovarian cyst          |.         ✅         | More common in ruptured endometriomas                   |Thick hyperdense cyst walls          |         ✅         | Thicker walls vs functional cysts (p < 0.05)            

|Loculated ascites confined to pelvis |         ✅         | Significantly more frequent in endometriomas 

| Pelvic fat infiltration / stranding   |         ✅         | Suggestive of inflammatory reaction from rupture        |

| Variable blood signal intensity      |         ✅         | Expected from repeated cyclic hemorrhage                |

What We Ruled Out (and How)

| Condition                 | Why ruled out?                                                                               |

| ------------------------- | -------------------------------------------------------------------------------------------- |

| Ruptured appendicitis| No peri-appendiceal epicenter of inflammation; appendix not thickened                        |

| TOA                 | No complex tubular mass, no pus-filled collection, no hyperemic adnexal inflammatory complex |

These distinctions are critical because:

• Appendicitis → urgent surgical management

• TOA → antibiotics + possible drainage

• Endometrioma rupture → often conservative or laparoscopy depending on severity

Correct diagnosis reduces unnecessary invasive procedures.

Pathophysiology Refresher

Endometriomas rupture due to:

• Increased intracystic pressure

• Adhesion-related traction

• Menstrual cycle hormonal changes

Spillage of degraded hemosiderin-rich content leads to:
✅ Severe chemical peritonitis
✅ Pain out of proportion
✅ Adhesions worsening endometriosis progression

This exact mechanism is emphasized in literature .

Final Diagnosis

Ruptured ovarian endometriotic cyst
with pelvic fat inflammatory reaction,
associated with deep infiltrating endometriosis,
without imaging evidence of appendicitis or TOA.

📚 Radiology Take-Home Messages

🔑 In women with acute pelvic pain:

• Endometriosis should always be in differential

• US may be nondiagnostic → CT/MRI are crucial next steps

• Look for:

  • Multiloculated adnexal cysts

  • Thick walls

  • Hemoperitoneum but confined to pelvis

  • Pelvic fat stranding + adhesions
    → Highly suggest ruptured endometrioma.