The Majority of literate people now understand that bleeding does not only occur when a person is cut by broken pieces of glass or struck by a wooden or metallic sharp object but can be a result of many environmental and physiological factors that affect our lives.Our body is made up of a network of veins and vessels that links all our body system. They are elastic, soft and flexible, characteristics that enable them to accomplish their duties. They supply blood and nutrients to all body parts.My main centre of focus here is internal bleeding, especially to vital organs. Internal bleeding occurs when there is a breakdown in our vascular system that consists of veins and vessels.The most common form of internal bleeding experienced in our society is gastro-intestinal bleeding either in upper part of the gastro-intestinal system or the lower part of the gastro-intestinal tract that involves the bowels, rectum and the anus.For example, in one of my clinics in Kigali, a 31-year-old security officer came complaining of anemia of unknown origin. He presented with mild to moderate generalised body weakness and persistent epigastric pains. His blood hemoglobin was very low 4.5 g/dl that was detected after full blood count done in one of private clinics in town.He was reportedly transfused three times with fresh blood in a space of two weeks before his arrival to the hospital for consultation. Even after he received blood three times, there was no improvement but instead the hemoglobin level kept going down to the expected limits. He was worried about his situation seemingly looked bored and tired of lying in clinical premises for blood transfusion.When I took history from him, he revealed to have spent four weeks passing out black stool. The black stool underlined the success of his treatment and definite solution to his problem.Full blood count also showed low level of hemoglobin. Other parameters in the blood count were very normal and this rule out other possible hematological complications.  He was also asked to go for endoscopy and barium exam to trace the origin of bleeding.His bleeding was found to originate in the stomach because of an aggravated gastritis. He was treated with medications and advised him on lifestyle approach to his illness.Normally, blood can be seen in vomits, scientifically referred to as hematemesis, or can pass out in stool as melena. Blood in the stool can be a result of several different conditions such as bleeding ulcer, esophageal varices and sometimes inflammation of the esophagus. The black appearance of the stool is from the blood having contact with the body’s digestive secretions.The black colour indicates that the blood has been in the body for some time, and that the bleeding is coming from the upper part of the gastro-intestinal tract.This is where clinicians differentiate bleeding from the upper part of the gastro-intestinal tract to that from the lower part of gastro-intestinal tract. In the lower gastro-intestinal bleeding, blood comes out in bright red colour and can easily be confirmed by a rectum examination or colonoscopy.Usually, stool colour is influenced by what you eat and the amount of bile product acting on the completed end-product of digestion.When bile pigments travel through the gastrointestinal tract, they become chemically altered by enzymes that changes them from green to brown. This gives the normal stool colour brown.If the stool is bright red or black in colour, indicates the presence of blood and immediate investigations should be done to trace the origin of blood stains.Some supplements such as iron and bismuth can also make the colour of stool appear black. Likewise cranberries, tomato juice or soup, red gelatin or drink mixes can make the colour to look red. However, these situations are not so common.When you notice that the colour of your stool appears light-coloured, white or clay-coloured, this means there is lack of bile in stool. This may indicate a bile duct obstruction problem. However, this should be accompanied by other signs and symptoms of bile duct obstruction. Dr Joseph Kamugisha is a resident oncologist in Jerusalem, Israel