Accessory uterine appendage may be a new Müllerian malformation.

Objective: To describe a case of an accessory uterine structure.

Design: Case report.

Setting: University affiliated, community-based hospital.

Patient(s): A 35-year-old woman who presented for laparoscopic tubal sterilization.

Intervention(s): Laparoscopy, tubal sterilization, dye test, and excision of accessory uterine structure.

Main Outcome Measure(s): Laparoscopic findings and resection of the anomaly.

Result(s): Laparoscopy showed a hollow uterine appendage that communicated with the uterine cavity. This was completely excised.

Conclusion(s): We report a rare case of a uterine anomaly that is inconsistent with the traditional classification system, and we offer a possible mechanism for its formation.