# A rare case of congenital appendiceal duplication complicated by an appendiceal-sigmoid fistula: A case report

## TL;DR

A rare case of a duplicated appendix connected to the colon was successfully treated with surgery in a 26-year-old woman.

## Contribution

First reported case of appendiceal duplication complicated by an appendiceal-sigmoid fistula.

## Key findings

- Appendiceal duplication and appendiceal-sigmoid fistula coexistence was confirmed during surgery.
- Preoperative imaging failed to identify the anomalies, highlighting diagnostic challenges.
- Surgical intervention led to full recovery and resolution of symptoms.

## Abstract

Duplication of the appendix is a rare congenital anomaly, occurring in approximately 0.004 % to 0.009 % of the population. In contrast, appendiceal-sigmoid fistulas are uncommon acquired conditions, usually associated with chronic inflammation or neoplastic processes. To our knowledge, the coexistence of these two entities has not been previously reported.

A 26-year-old female presented with a one-month history of right lower quadrant abdominal pain, loss of appetite, and low-grade fever. Imaging findings initially suggested chronic appendicitis. During exploratory laparotomy, a Type A appendiceal duplication was discovered, with one of the appendices forming a fistulous connection to the sigmoid colon. Surgical treatment involved appendectomy, excision of the fistula, and primary repair of the colonic defect. Histopathological examination confirmed the diagnosis of duplicated appendix with chronic inflammatory changes. The patient had an uneventful postoperative recovery.

Appendiceal duplication typically remains an incidental finding, rarely causing clinical symptoms. The coexistence of appendiceal duplication and sigmoid fistula formation haven't been previously reported. Diagnosis can be challenging due to the limitations of preoperative imaging in identifying these anomalies. Therefore, surgical exploration remains crucial, particularly in symptomatic patients, to manage symptoms and prevent potential complications.

Clinicians should maintain a high index of suspicion for rare congenital anomalies like appendiceal duplication in patients who present with atypical symptoms of appendicitis.

•Appendiceal duplication is a rare anomaly (0.004%–0.009% incidence).•Appendiceal-sigmoid fistulas are rare and often result from chronic inflammation or tumors.•First reported case of duplicated appendix with an appendiceal-sigmoid fistula.•Diagnosis was made intraoperatively due to imaging limitations.•Surgery led to full recovery after appendectomy and colonic repair.

Appendiceal duplication is a rare anomaly (0.004%–0.009% incidence).

Appendiceal-sigmoid fistulas are rare and often result from chronic inflammation or tumors.

First reported case of duplicated appendix with an appendiceal-sigmoid fistula.

Diagnosis was made intraoperatively due to imaging limitations.

Surgery led to full recovery after appendectomy and colonic repair.