Poor bowel preparation for colonoscopy and colonoscopy are not necessarily in vain. If there is a moderate amount of fecal water in the segments of the bowel, but the segments of the colon can still be observed smoothly by changing positions through suction, it will not affect the final observation results. If there is a large amount of foul, dilute feces in the bowel, observation may be severely compromised, an accurate diagnosis cannot be made, and the examination needs to be stopped. Poor bowel preparation does affect the examination results, but if the doctor gives a clear diagnosis, it means that basically all has been seen clearly, and there is no need to worry too much; however, if the doctor can not see clearly at all, and it is difficult to make a diagnosis, it is necessary to do a good job of bowel preparation again, and re-examination.