How can i tell if i have melena (blood in my intestines)?

Stool test 4 blood: Melena is commonly used to refer to old blood in the stool, giving it a characteristic blackish color and noticeable smell, as any nurse/med student can tell you. A simple stool test for hidden blood (guiac or hemoccult) can differentiate it from other possible causes and lead to prompt evaluation if needed, or reassurance if not!