Melena Stool Definition, Causes and More: Understand melena stool, dark and tarry stool often indicating upper gastrointestinal bleeding. Learn about potential causes and implications.: Arpilor, Mr. Leonardimer: 9798859376544: Amazon.com: Books Retroflexions.com The Rectal Bleeding Rainbow Melena What does your poop colour indicate? Pay attention. There's a lot to be learned by the colour and consistency of your stools, as well as the frequency and how easily passed