The severity grading of acute cholecystitis following the Tokyo Guidelines is the most powerful predictive factor for conversion from laparoscopic cholecystectomy to open cholecystectomy.

Background: The relationship between the severity assessment of acute cholecystitis based on the Tokyo Guidelines and the risk for conversion from laparoscopic surgery to open surgery has been assessed in few previous reports, with conflicting results.

Methods: A retrospective review of patients with acute cholecystitis within a single system from 2010 to 2013 was performed. The diagnosis and severity of acute cholecystitis were assigned by the Tokyo Guidelines 2013 (TG13). The primary outcome measure was conversion to open cholecystectomy.

Results: During the period of study, 493 patients were operated by laparoscopy for acute cholecystitis. Laparoscopic cholecystectomy was intraoperatively converted to open surgery in 56 cases (11.4%). The multivariate analysis showed that the risk factors for conversion to open surgery included male gender (OR: 2.15; IC [1.18-3.9]), diabetes (OR: 2.22; IC [1.13-4.33]), total bilirubin levels (OR: 1.02; IC [1-1.05]), and the TG13 severity classification (OR: 4.44; IC [2.25-8.75]).

Conclusions: The independent risk factors for conversion to open surgery included male sex, diabetes mellitus, total bilirubin level, and TG13 grade. TG13 grade was found to be the most powerful predictive factor for conversion as it had the highest OR.