The investigators plan to adopt a thorough flushing strategy when withdrawing the endoscope, and have zero tolerance for the liquid and foam in the intestinal lumen. Observe and compare the impact of this strategy with traditional limited degree suction methods on the results of colonoscopy. The research group and the control group respectively adopted a thorough flushing strategy and a limited flushing strategy, and compared the total time of colonoscopy examination, the time of withdrawal, the detection rate of polyps, the detection rate of small polyps, and the amount of flushing fluid between the two groups. Analyze the value of thorough flushing strategy for the efficiency and quality of colonoscopy examination.

Most physicians do not adopt a strategy of complete suction of fluid from the intestinal lumen during colonoscopy. There are both concerns about the time required for colonoscopy and the possibility of inability to thorough cleannig up. Some endoscopists believe that the visual field for partial cleaning of fecal water is acceptable and does not affect observation. This study aims to make an observation and comparison based on the existing problems mentioned above. With the help of direct water injection system, the investigators plan to adopt a thorough flushing strategy when withdrawing the endoscope, and have zero tolerance for the liquid and foam in the intestinal lumen. Observe and compare the impact of this strategy with traditional limited degree suction methods on the results of colonoscopy. The research group and the control group respectively adopted a thorough flushing strategy and a limited flushing strategy, and compared the total time of colonoscopy examination, the time of withdrawal, the detection rate of polyps, the detection rate of small polyps, and the amount of flushing fluid between the two groups. Analyze the value of thorough flushing strategy for the efficiency and quality of colonoscopy examination.

Inclusion Criteria:

• People without contraindications for colonoscopy

Exclusion Criteria:

• Patients diagnosed with colon polyps

160 patients were selected for colonoscopy examination and randomly assigned to the study group and control group. The two groups used a thorough flushing strategy and a limited flushing strategy to complete colonoscopy examination. The research group adopted a thorough flushing strategy, while the control group adopted a limited flushing strategy. The thorough flushing strategy refers to the thorough flushing of all liquid and foam accumulation areas during the inspection. Make all the liquid accumulation parts in the intestinal cavity free of aspiratable liquid retention. The limited flushing strategy refers to not pursuing full liquid suction, but flushing until it is clear enough for observation. The limited flushing strategy is currently the conventional flushing method for colonoscopy.