In a woman with a prior history of tuberculosis at age 36 who now presents with ascites and a CT scan showing no ovarian mass, what is the appropriate diagnostic work‑up to differentiate peritoneal tuberculosis from ovarian carcinoma?

Diagnostic Work-Up for Peritoneal TB vs. Ovarian Carcinoma

In a woman with prior TB history presenting with ascites and no ovarian mass on CT, diagnostic laparoscopy with peritoneal biopsy is the definitive diagnostic procedure to differentiate peritoneal tuberculosis from ovarian carcinoma, as imaging and tumor markers cannot reliably distinguish between these conditions 1, 2.

Initial Diagnostic Algorithm

Step 1: Laboratory Assessment

• CA-125 measurement - While elevated CA-125 (often >1000 U/mL) occurs in both conditions, it cannot differentiate between them 3, 1
• Ascitic fluid analysis including:
  • Adenosine deaminase (ADA) activity - elevated ADA combined with high clinical suspicion is effective for peritoneal TB diagnosis 4
  • Cytology (though often non-diagnostic)
  • Acid-fast bacilli staining and TB culture
• QuantiFERON-TB Gold or IGRA testing 5
• Consider CEA and CA 19-9 if mucinous pathology suspected 3

Step 2: Imaging Evaluation

• CT thorax, abdomen, and pelvis - Standard work-up per ovarian cancer guidelines 3
• Transvaginal and transabdominal ultrasound - Use IOTA models to assess adnexal masses 3
• Chest radiography - To evaluate for pulmonary TB, though peritoneal TB can occur without active pulmonary disease 6

Critical caveat: Imaging findings of peritoneal thickening, omental cake, ascites, and peritoneal nodules are identical in both peritoneal TB and peritoneal carcinomatosis 7, 1, 2. CT cannot reliably differentiate these conditions.

Step 3: Definitive Diagnosis - Laparoscopy

When less invasive tests are inconclusive, proceed directly to diagnostic laparoscopy 1, 2. This is the gold standard because:

• Direct visualization of peritoneal cavity reveals pathognomonic findings:

  • Miliary nodules covering peritoneal surfaces (TB)
  • Omental cake appearance
  • Peritoneal studding patterns

• Tissue biopsy for:

  • Histopathology showing granulomatous inflammation with caseating necrosis
  • Ziehl-Neelsen staining for acid-fast bacilli
  • TB culture and PCR confirmation
  • Simultaneous exclusion of malignancy 1, 5

Key Clinical Features Favoring TB Over Malignancy

High-risk demographics and history:

• Prior TB history (as in this patient) 6
• Endemic country origin or residence
• Constitutional symptoms: night sweats, weight loss, fever 6, 4
• Younger age (TB more common in reproductive years, though can occur at any age) 1, 5

Imaging clues suggesting TB:

• Ascites with no or minimal ovarian mass (ovarian cancer typically has identifiable adnexal mass) 1
• Peritoneal thickening with nodularity
• Lymphadenopathy patterns

Critical Pitfalls to Avoid

1. Do not assume elevated CA-125 + ascites = ovarian cancer - CA-125 can reach >1200 U/mL in peritoneal TB 1

2. Do not delay laparoscopy when non-invasive tests are inconclusive - delays lead to unnecessary chemotherapy or extensive surgery 2, 8

3. Consider coexistence - Rare cases document simultaneous peritoneal TB and ovarian carcinoma, particularly in endemic areas 9. Histopathology must evaluate for both.

4. Do not rely on ascitic fluid cytology alone - Repeatedly negative cytology does not exclude malignancy but should raise suspicion for TB 2

When to Proceed Directly to Laparoscopy

Immediate laparoscopy is indicated when:

• Ascites + elevated CA-125 + absent or minimal ovarian mass on imaging
• Prior TB history or TB-endemic origin
• Constitutional symptoms present
• Ascitic fluid analysis non-diagnostic or suggests TB (elevated ADA)
• Multiple negative cytologies for malignancy 1, 2

The diagnostic pathway prioritizes tissue diagnosis via laparoscopy over empiric treatment, as misdiagnosis leads to either unnecessary oncologic surgery/chemotherapy or delayed TB treatment with deteriorated prognosis 2, 8.