Grade III (severe) acute cholecystitis	Grade II (moderate) acute cholecystitis	Grade I (mild) acute cholecystitis
Grade III acute cholecystitis is associated with dysfunction of any 1 of the following organs/systems: cardiovascular dysfunction: hypotension requiring treatment with dopamine ≥ 5 μg/kg per minute, or any dose of noradrenaline; neurological dysfunction: decreased level of consciousness; respiratory dysfunction: PaO2/FiO2 ratio < 300; renal dysfunction: oliguria, creatinine > 2.0 mg/dL; hepatic dysfunction: PT‐INR > 1.5; haematological dysfunction: platelet count < 100000/mm3.	Grade II acute cholecystitis is associated with any 1 of the following conditions: elevated WBC count (> 18,000/mm3); palpable tender mass in the right upper abdominal quadrant; duration of complaints > 72 hours; marked local inflammation (gangrenous cholecystitis, pericholecystic abscess, hepatic abscess, biliary peritonitis, emphysematous cholecystitis).	Grade I acute cholecystitis does not meet the criteria of Grade III or Grade II acute cholecystitis. It can also be defined as acute cholecystitis in a healthy person with no organ dysfunction and mild inflammatory changes in the gallbladder, making cholecystectomy a safe and low‐risk operative procedure.