*2.1. Study Design*

A 2-year retrospective study was performed on the patients admitted in the 4th Department of Surgery, Emergency University Hospital Bucharest for acute cholecystitis who underwent emergency cholecystectomy, between January 2018 and December 2019. Data were collected from observation charts and postoperative notes.

The diagnosis of acute cholecystitis was assessed according to Tokyo Guidelines, based on clinical findings (Murphy sign; right upper quadrant pain, tenderness, palpable mass, fever), laboratory inflammation tests and an ultrasound exam confirming gallstones and thickness of the gallbladder wall. The inclusion criteria for the study consisted of: (I) emergency admission for acute cholecystitis followed by cholecystectomy during the same hospital admission, (II) accurate documentation of the clinical signs, paraclinical data, surgery and complications. Exclusion criteria were: (I) associated pancreatitis or any (II) malignancy.

The preoperative evaluation of the anesthetic-surgical risk was based on the American Society of Anesthesiologists Physical Status Classification (ASA PS). The severity of acute cholecystitis was evaluated according to Tokyo Guidelines criteria (TG13/TG18) (Table 1). Charlson Comorbidity Index (CCI) scores were calculated retrospectively for the patients enrolled in the study based on the comorbidities documented in the observation charts.

