Predicting length of stay and conversion to open cholecystectomy for acute cholecystitis using the 2013 Tokyo Guidelines in a US population.

Background: The 2013 Tokyo Guidelines (TG13) for acute cholecystitis have not been studied extensively in US populations.

Methods: A retrospective review of patients with acute cholecystitis within a single system from 2009 to 2013 was performed. The diagnosis and severity of acute cholecystitis were assigned by the TG13.