Tarry stool, medically termed melena, refers to black, sticky, and foul-smelling feces. This distinctive appearance often signals a serious underlying health concern, typically internal bleeding within the upper digestive tract. Recognizing melena is important for understanding and addressing potential medical conditions.
Identifying Tarry Stools: Appearance and Characteristics
Tarry stools are recognizable by their unique look and odor. Their color is typically jet black, resembling road tar or coffee grounds, and they have a shiny, viscous, and sticky consistency. This helps differentiate them from other dark stools.
Melena stools also have a distinctively strong, offensive odor, sometimes described as sickeningly sweet or metallic. This pungent smell results from the breakdown of blood by digestive enzymes and intestinal bacteria. These characteristics suggest the presence of digested blood and indicate a potential issue requiring medical attention.
The Primary Medical Reason: Upper Gastrointestinal Bleeding
The most frequent cause of tarry stools is bleeding in the upper gastrointestinal (GI) tract, including the esophagus, stomach, and duodenum. The black color develops as hemoglobin in the blood interacts with digestive enzymes and stomach acid during its passage through the digestive system, transforming bright red blood into the dark, tarry substance.
Several conditions can lead to upper GI bleeding. Peptic ulcers (sores in the stomach or duodenum lining) are a common cause. Other sources include esophageal varices (enlarged veins in the esophagus often linked to liver disease), and gastritis (inflammation of the stomach lining). Mallory-Weiss tears (lacerations in the esophagus typically caused by severe vomiting) and certain cancers of the esophagus, stomach, or pancreas can also result in such bleeding.
Other Reasons for Dark Stools
While tarry stools often indicate bleeding, certain foods and medications can also cause stools to appear dark or black without internal hemorrhage. These typically lack the tarry consistency and strong odor of true melena. This distinction helps prevent unnecessary alarm.
For example, black licorice, blueberries, dark chocolate, blood sausage, or beets can temporarily darken stools. Medications like iron supplements, bismuth subsalicylate (found in products like Pepto-Bismol), and activated charcoal are also known to turn stools black. In these instances, the dark coloration is usually harmless and resolves once the offending food or medication is stopped.
When to Seek Medical Attention and How it’s Diagnosed
Any instance of tarry stool should prompt immediate medical consultation due to potential serious underlying bleeding. Additional concerning symptoms include dizziness, weakness, fainting, abdominal pain, or shortness of breath. Vomiting blood, especially if it resembles coffee grounds, is another urgent sign.
When melena is suspected, diagnosis typically begins with a physical examination and a detailed review of the patient’s medical history. Stool tests, such as a fecal occult blood test, can detect blood. Blood tests, including a complete blood count, assess for anemia and blood loss. An upper endoscopy (EGD) is often the definitive diagnostic tool, using a thin tube with a camera to visualize the upper GI tract and identify the bleeding source.
General Treatment Approaches
Treatment for tarry stools depends on the identified cause of bleeding. Once the source is located, medical professionals implement targeted interventions. For conditions like peptic ulcers, medications such as proton pump inhibitors (PPIs) are prescribed to reduce stomach acid and promote healing.
Endoscopic procedures performed during an EGD can directly address bleeding. Techniques include injecting medications into the bleeding site, using thermal energy to cauterize blood vessels, or applying clips or bands to stop bleeding. In severe cases where bleeding is extensive or does not respond to less invasive methods, surgical intervention may be necessary. Supportive care, such as fluid replacement and blood transfusions, is often provided to manage blood loss and stabilize the patient.