Whether or not you can have a colonoscopy after taking laxatives depends on the condition of the yellow water, which is transparent and not cloudy, and on the other hand, the yellow water is opaque and cloudy with fecal sludge deposits can’t be done. 1. yellow water transparent and not turbid: after taking laxatives has been pulling yellow water, if the yellow water is transparent, clearer, no excess fecal slag, indicating that the intestinal environment is better prepared for colonoscopy, and at the same time can improve the detection rate of disease. 2. Yellow water is opaque and turbid with fecal slag precipitation: after taking laxatives has been pulling yellow water, if the yellow water is turbid, can see a small amount or a large amount of fecal slag, you can not do a colonoscopy, in this case for colonoscopy will affect the doctor’s field of vision observation, which may lead to a misdiagnosis or leakage of the diagnosis. Doing colonoscopy needs a good intestinal environment, in order to make the test results accurate, it is recommended that patients should follow the doctor’s instructions, and make good preparations before the colonoscopy.