Inclusion Criteria:  have a diagnosis of Acute Calculous Cholecystitis (ACC) as defined by Tokyo Guidelines 2018 criteria be candidate to Early Cholecystectomy (EC) during the index admission* be ≥ 18 years old be stratified for the risk of Common Bile Duct Stones (CBDS) according to the Israelian Score, and, in case of confirmation of CBDS receive pre-operative Endoscopic Retrograde Cholangiopancreatography (ERCP). provide signed and dated informed consent form  willing to comply with all study procedures and be available for the duration of the study.  All the patients treated with initial open cholecystectomy, those who undergo Early Laparoscopic Cholecystectomy (ELC), those with conversion from laparoscopic to open cholecystectomy or those who undergo bail out procedures (e.g. subtotal cholecystectomy) will be included.  Exclusion Criteria:  pregnancy or lactation acute cholecystitis not related to a gallstone etiology onset of symptoms >10 days before cholecystectomy** concomitant cholangitis or pancreatitis intraoperative treatment of common bile duct stones  anything that would place the individual at increased risk or preclude the individual's full compliance with or completion of the study.  Patients with ACC associated with common bile duct stones who underwent pre-operative ERCP could be included if they receive EC within 10 days from onset of symptoms