Clear yellowish water before colonoscopy is acceptable, but turbid yellow water is not acceptable. If the stool is clear or clear yellow water before colonoscopy, it means that the bowel is well prepared and colonoscopy is feasible. If it is cloudy yellow water, it means that the intestinal tract is not well-prepared for colonoscopy, and colonoscopy can not clearly observe the lesions of the intestinal mucosa, which will easily lead to leakage and misdiagnosis. Before colonoscopy, you need to take laxatives to empty the intestines, and only when the intestines are well prepared can you perform colonoscopy. This can avoid inaccurate results and repeated examinations. 2~3 days before the colonoscopy to the main non-dregs diet, such as rice porridge, noodles, steamed bread, milk and so on. Avoid greasy, spicy and other foods. For the case of colonoscopy pulling yellow water, it is recommended that the doctor determine whether colonoscopy is feasible.