AIM: To clarify the effectiveness of CO2 insufflation in potentially difficult colonoscopy cases, particularly in relation to the experience level of colonoscopists.METHODS: One hundred twenty potentially difficult cases were included in this study, which involved females with a low body mass index and patients with earlier abdominal and/or pelvic open surgery or previously diagnosed left-side colon diverticulosis. Patients receiving colonoscopy examinations without sedation using a pediatric variable-stiffness colonoscope were divided into two groups based on either CO2 or standard air insufflation. Both insufflation procedures were also evaluated according to the experience level of the respective colonoscopists who were divided into an experienced colonoscopist (EC) group and a less experienced colonoscopist (LEC) group. Study measurements included a 100-mm visual analogue scale (VAS) for patient pain during and after colonoscopyexaminations, in addition to insertion to the cecum and withdrawal times.RESULTS: Examination times did not differ, however, VAS scores in the CO2 group were signifi cantly better than in the air group (P < 0.001, two-way ANOVA) from immediately after the procedure and up to 2 h later. There were no significant differences between either insufflation method in the EC group (P = 0.29), however, VAS scores for CO2 insufflation were significantly better than air insufflation in the LEC group (P = 0.023) immediately after colonoscopies and up to 4 h afterwards.CONCLUSION: CO2 insufflation reduced patient pain after colonoscopy in potentially difficult cases when performed by LECs. AIM: To clarify the effectiveness of CO2 insufflation in potentially difficult colonoscopy cases, particularly in relation to the experience level of colonoscopists. METHHODS: One hundred and ten thousand for prevention of patients were included in this study, which involved females with a low body mass index and patients with earlier abdominal and / or pelvic open surgery or previously diagnosed left-side colon diverticulosis. Patients receiving colonoscopy examinations without sedation using a pediatric variable-stiffness colonoscope divided into two groups based on either CO2 or standard air insufflation. Both insufflation procedures were also evaluated according to the experience level of the respective colonoscopists who were divided into an experienced colonoscopist (EC) group and a less experienced colonoscopist (LEC) group. colonoscopyexaminations, in addition to insertion to the cecum an d withdrawal times. RESULTS: Examination times did not differ, however, VAS scores in the CO2 group were signifi cantly better than in the air group (P <0.001, two-way ANOVA) from immediately after the procedure and up to 2 h later . There were no significant differences between either insufflation method in the EC group (P = 0.29), however, VAS scores for CO2 insufflation were significantly better than air insufflation in the LEC group (P = 0.023) immediately after colonoscopies and up to 4 h afterwards.CONCLUSION: CO2 insufflation reduced patient pain after colonoscopy in potentially difficult cases when performed by LECs.