Dark-colored particles in the stool 2 months after the surgery may be caused by bad dietary habits or bleeding from stress ulcers. 1. Bad eating habits: If you often eat some dark-colored food after surgery, such as pig’s blood or dragon fruit, you may have dark-colored particles in your stool. 2. Stress ulcer bleeding: when you have gastric ulcer or duodenal ulcer and other lesions before having the surgery, the process of having the surgery will lead to aggravation of the condition, which will cause bleeding in the stool, thus inducing dark stool color. Two months after the operation, the stool has been dark-colored particles need to adjust the diet, such as symptoms continue to need to go to the hospital in time to do the examination, according to the cause of timely treatment.