What is it about ?
A melena refers to black stools because they contain blood. Blood turns black after digestion with stomach acid, enzymes, and bacteria in the digestive tract.
The presence of red blood in or on the stool indicates a cause localized in the area of the anus (for example hemorrhoids). The cause of a melena is usually bleeding much higher in the digestive tract (for example in the stomach or the first part of the duodenum).
It takes about 100 to 200 milliliters of blood to cause melena. It can be caused by a single heavy bleeding or by limited but persistent blood loss, as is sometimes the case with stomach ulcers.
Stools may also turn black when taken with iron, bismuth (a chemical found in many medicines and cosmetics), or certain nutrients. In this case, we are not talking about melena because there is no bleeding.
How to recognize it?
Melena is mainly characterized by black, tarry, smelly stools. Symptoms of the condition causing the bleeding can sometimes be added.
If you vomit blood before having melena, the bleeding is in the esophagus or stomach. Pain in the stomach area may indicate a stomach ulcer.
A change in bowel movements (an alternation of constipation and diarrhea) associated with weight loss or loss of appetite are possible signs of a bowel tumor.
If you lose small amounts of blood for a long time or you have regular bleeding, you risk anemia. If you are anemic, you tire quickly and you have pale skin.
If you have sudden heavy bleeding, your pulse may speed up, your blood pressure may drop, and in the end you may even go into shock.
How is the diagnosis made?
If he suspects a melena, the doctor will always do additional examinations to find the cause. A blood test will allow her to see if you have anemia from the blood loss. You can also test a small amount of stool to see if it contains blood.
The doctor will also schedule an endoscopy of the esophagus and stomach (gastroscopy). The diagnosis can thus be made in a little more than half of the cases. If not, your doctor will still order a large intestine endoscopy (colonoscopy).
If you vomit a lot of blood or show signs of shock or heart failure, you will be admitted to the emergency room.
What can you do ?
If your stools turn black, see the doctor. The cause must always be identified.
It is important to find colorectal cancer at an early stage. Colorectal cancer screening is organized in Wallonia by the Community Reference Center for Cancer Screening (CCR) and in Brussels by Brumammo. It is completely free for those aged 50 to 74 and is easy to do at home.
What can your doctor do?
The doctor will refer you to a gastroenterologist for further examinations and appropriate treatment.
Want to know more?
- Colorectal cancer screening (video) – Fondation contre le cancer
- Order your screening kit – Wallonia – CCR – Community Reference Center for cancer screening
- Colorectal cancer screening program in Brussels – Brumammo
- Colorectal cancer screening – Colonoscopy, here, Where on this page of the CCR – Community Reference Center for cancer screening
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