Conversion Rates, Causes and Preoperative Associated Factors in 3411 Laparoscopic Appendectomies: Insights after nearly three decades of laparoscopy and an analysis of the Learning Curve.

Introduction: Laparoscopic appendectomy is the current gold standard in treating acute appendicitis. Despite the low frequency of conversion to open surgery, it remains necessary in certain cases. Our primary outcome is to identify the conversion rate of laparoscopic appendectomy to open surgery and how this rate has changed over the learning curve. Secondly, we aim to determine the causes of conversion, their changes in frequency over time and to identify preoperative factors associated with conversion.

Methods: A retrospective comparative study with prospective case registry was conducted. All patients who underwent laparoscopic appendectomy from January 2000 to December 2023 at a high-volume center were analyzed. The series was divided into six periods, each spanning four years. All patients who underwent totally laparoscopic appendectomy (TLA) and those requiring conversion to open appendectomy (COA) were included.

Results: A total of 3411 appendectomies were performed during the study period, with an overall conversion rate of 0.96% (33/3411). Our analysis showed that after the first three periods (12 years), the conversion rate decreased and reached a plateau of approximately 0.4%. The most common causes of conversion were perforation of the appendix base (9/33), abdominal cavity adhesions (8/33) and pneumoperitoneum intolerance (3/33). Age over 65, American Society of Anesthesiologists (ASA) score III/IV and symptom duration exceeding 24 hours were preoperative factors significantly associated with conversion at univariate analysis. However, only age (p 0.0001) and symptoms exceeding 24 hours (p 0.01) remained independently associated with conversion after multivariate analysis.

Conclusion: In experienced centers, conversion from laparoscopic appendectomy to open appendectomy is uncommon, but remains necessary in certain cases. Despite identifying a population with higher association with conversion which should be advised preoperatively, due to the low incidence of conversions once the learning curve is overcome, an initial laparoscopic approach is the preferred choice.