Brief Answer: Suggest a detailed history and tests Detailed Answer: Hi, Welcome to our site. I am Doctor Mittal Read your query, that is a very significant question and I appreciate your problem. I will try my best to answer your query. The possibilities of development of dark smelly stools in a patient with diabetic nephropathy and coronary artery disease. I would like to know if the dark stools are black, or just dark. cause a black smelly stool could mean there is some passage of blood. Alternatively there is a possibility that the food items he is having are imparting the colour to the stools. There is a third possibility that he might be on iron tablets or therapy which also imparts a black colour to the stools. A possibility of gastrointestinal infection is always present. I would like to advice a few tests, namely stool routine and occult blood, complete hemogram, and pt/inr. the tests are meant to find out the exact status of the stools as far as infection and passage of blood are concerned. a complete hemogram would give us a clue regarding both, an infection and loss of blood. with a history of bypass, the possibility is strong that he is on blood thinners. I would like to find out just how thin the blood may have become. A colonoscopy can be planned as well, but preferably at a later date, after the current tests are reported and considered. Meanwhile a proton pump inhibitor can be initiated along with a mild antibiotic. your regular physician would surely know about that. I hope this helps you. Inform the reports mentioned above, so I can be of help further. Best of luck, Dr Mittal

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