Appendico-sigmoid-cutaneous fistula following percutaneous drainage of a periappendiceal abscess: a case report.

Introduction and importance: Appendico-colonic fistula and appendico-cutaneous fistula are rare complications of appendicitis. Their concurrent occurrence is exceptionally uncommon and poses diagnostic and therapeutic challenges. Case presentation: A 60-year-old woman presented with recurrent right lower quadrant pain and persistent feculent drainage 2 months after percutaneous drainage for a periappendiceal abscess. Computed tomography (CT) showed perforated appendicitis with a periappendiceal abscess but did not clearly identify the fistulous tract. Drainage-catheter fistulography, CT after fistulography, and a transanal water-soluble contrast study demonstrated communication among the sigmoid colon, periappendiceal abscess cavity, and abdominal wall drainage tract, confirming an appendico-sigmoid-cutaneous fistula. She underwent laparoscopic appendectomy, partial resection of the involved sigmoid wall, and complete excision of the abdominal wall fistulous tract. Colonic continuity was preserved, and no colostomy was created. No postoperative complications occurred according to the Clavien-Dindo classification, and she remained recurrence-free at a 9-month follow-up. Discussion: Persistent purulent or feculent drainage after percutaneous drainage of a periappendiceal abscess should raise suspicion for a complex appendiceal fistula. Water-soluble contrast studies through different routes may provide decisive diagnostic evidence when CT findings are inconclusive. Conclusion: Early multimodal imaging evaluation and timely definitive surgery are essential for the diagnosis and management of complex appendiceal fistulas.