Carbon dioxide insufflation during withdrawal of the colonoscope improved postprocedure discomfort: A prospective, randomized, controlled trial

In colonoscopy, the question of when and how to use carbon dioxide (CO2) insufflation remains uncertain. Inspection for the pathological changes during colonoscopy takes place during the withdrawal of the scope. This study aimed to determine whether CO2 insufflation only at the withdrawal of the colonoscope has an effect comparable to that of CO2 usage throughout the course of the procedure. Symptomatic patients were randomized in three groups: (1) patients given air insufflation (A; n = 33); (2) patients given CO2 insufflation only at the time of scope withdrawal (CW; n = 33); and (3) patients given the CO2 insufflation (C; n = 34) for the whole course of the colonoscopy. Patients were requested to answer questionnaires about their pain score during, at the end, and 1 h after the colonoscopy by using a pain numerical scale ranging from 0 to 10. The disparities of the pain score were noted at the end of the procedure and 1 h after the procedure (p = 0.026 and p < 0.001, respectively). We further analyzed the scores between two of the three groups. Both CW (vs. A; procedure end: p = 0.012, 1 h after: p = 0.001) and C (vs. A; procedure end: p = 0.072, 1 h after: p < 0.001) showed less postprocedure pain when compared with the group A. The pain score between CW and C were similar at each time segment (procedure end: p = 0.555, 1 h after: p = 0.491). CO2 insufflation merely at the withdrawal of the colonoscope improved postprocedural abdominal discomfort and the effect was not inferior to that of full course CO2 insufflation.