Objective:To investigate the clinical characteristics and surgical effects of acute calculous cholecystitis (ACC) in high altitude area of Tibet.Methods:The retrospective cohort study was conducted. The clinicopathological data of 182 ACC patients who underwent surgery in the 954th Hospital of Army from January 2016 to December 2020 were collected. There were 56 males and 126 females, aged (41±13)years. Of the 182 patients, 61 cases undergoing open cholecystec-tomy were divided into the open group, and 121 cases undergoing laparoscopic cholecystectomy (LC) were divided into the laparoscopic group. Observation indicators: (1) clinical characteristics of ACC in high altitude area; (2) surgical situations; (3) postoperative complications; (4) follow-up. Follow-up was conducted using outpatient examination and telephone interview to detect postopera-tive complications of patients up to October 2021. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was conducted using the t test. Measure-ment data with skewed distribution were represented as M( Q1, Q3) or M(range), and comparison between groups was conducted using the Mann-Whitney U test. Count data were expressed as absolute numbers or percentages, and comparison between groups was conducted using the chi-square test. Results:(1) Clinical characteristics of ACC in high altitude area. Of the 182 patients, cases with symptom duration as <3 days, 3 days to 1 month, >1 month and ≤12 months, >12 months were 37, 43, 57, 45, respectively. Seventy-seven of the 182 patients were combined with other diseases before surgery. (2) Surgical situations. Two cases in the open group were found common bile duct stones during the operation, and underwent choledochotomy and T-tube drainage. Nine cases in the laparoscopic group were converted to laparotomy, including 3 cases with severe abdominal adhesion and ineffective hemostasis, 6 cases with anatomical variation of Calot triangle. The conversion to laparotomy rate was 7.438%(9/121). The other patients in the open group and the laparoscopic group completed surgery successfully. The operation time, volume of intraoperative blood loss, time to postoperative first out-of-bed activities, time to postoperative first flatus, cases with indwelling drainage tube, cases with acute simple cholecystitis, acute suppurative cholecystitis, acute gangrene cholecystitis, gallbladder perforation of disease pathological type, postoperative white cell count, postoperative neutrophil percentage, duration of postoperative hospital stay were (109±42)minutes, 50(45,100)mL, (16.1±1.5)hours, (31.4±11.9)hours, 33, 25, 27, 6, 3, (6.8±1.9)×10 9/L, 72.7%±7.4%, (7.3±1.7)days for the open group. The above indicators were (98±43)minutes, 20(20,50)mL, (12.9±1.4)hours, (26.7±12.1)hours, 51, 56, 51, 9, 5, (7.1±2.4)×10 9/L, 70.5%±8.7%, (6.4±1.7)days for the laparoscopic group. There were significant differences in the volume of intraopera-tive blood loss, time to postoperative first out-of-bed activities, time to postoperative first flatus, duration of postoperative hospital stay between the two groups ( Z=?6.75, t=14.41, 2.46, 3.45, P<0.05). There was no significant difference in the operation time, cases with indwelling drainage tube, diseases pathological type, postoperative white cell count, postoperative neutrophil percentage between the two groups ( t=1.66, χ2=2.33, 0.84, t=?0.71, 1.66, P>0.05). (3) Postoperative complica-tions. Postoperative complications occurred in 7 of the 61 patients in the open group and 5 of the 121 patients in the laparoscopic group. There was no significant difference in the postoperative complications between the two groups ( χ2=2.46, P>0.05). (4) Follow-up. Of the 182 patients, 115 cases including 35 cases in the open group and 80 cases in the laparoscopic group were followed up for 12(range, 3?24)months. During the follow-up, 1 case of the 35 patients in the open group had abdominal pain and jaundice, which was diagnosed as choledocholithiasis. The patient was improved after stone removal with endoscopic retrograde cholangiopancreatography. Two cases of the 35 patients in the open group had upper abdominal pain with fever and were improved after anti-infection treatment. Of the 80 patients in the laparoscopic group, 1 case had upper abdominal pain and 1 case had dyspepsia and anorexia, respectively. The two cases were improved after symptomatic treatment. Conclusions:Patients with ACC in the high altitude area of Tibet have high ratio of preoperative complications, long diseases history and high incidence rates of pyogenic perforation of the gallbladder. Patients with ACC in the high altitude area undergoing LC is safe and effective. Compared with open cholecystectomy, LC have less volume of intraoperative blood loss, faster postoperative recovery and shorter duration of postoperative hospital stay.