When is stool color concerning? Black, tarry stools are NOT normal. They could be a sign of Melena upper gastrointestinal bleeding that requires urgent medical attention. Learn the difference between Melena vs Hematochezia, common A change in the colour of one's stools may sometimes be due to dietary changes; though it could also reveal something about one's health. Where stool appears or , it What is the cause of recurrent melena stool with multiple telangiectasia and prominent veins in the proximal ascending colon in a 14 year old boy?