A vesico-vaginal fistula (VVF) following obstructed labour is BEST characterised by which histological finding at the fistula margin that distinguishes it from post-surgical VVF?

• A Acute inflammatory infiltrate with neutrophil margination
• B Avascular fibrosis and ischaemic necrosis of the fistula edge due to pressure necrosis ✓
• C Well-vascularised granulation tissue with minimal fibrosis
• D Transitional epithelium lining the fistulous tract

Explanation

Obstetric VVF (from prolonged obstructed labour) results from ischaemic pressure necrosis — the fetal presenting part compresses the bladder wall against the pubic symphysis for hours, producing avascular fibrosis, dense scarring, and poor-quality tissue margins. This explains why obstetric VVF repair has lower success rates and requires waiting 3–6 months for tissue quality to improve. Post-surgical VVF has sharper, better-vascularised edges and may be repaired earlier. Acute inflammation characterises early injury, not established fistula.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.