Melena
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (December 2011) |
Melena | |
---|---|
Other names | Melaena, melæna |
Pronunciation | |
Specialty | General surgery, gastroenterology |
Symptoms | Dark blood in stool |
Causes |
Melena or melaena refers to the dark black, tarry feces that are associated with upper gastrointestinal bleeding.[1] The black color and characteristic strong odor are caused by hemoglobin in the blood being altered by digestive enzymes and intestinal bacteria.[2]
Causes
The most common cause of melena is
Causes of upper gastrointestinal bleeding that may result in melena include malignant tumors affecting the esophagus, stomach or small intestine, hemorrhagic blood diseases, such as
Causes of "false" melena include
Melena is considered a medical emergency as it arises from a significant amount of bleeding. Urgent care is required to rule out serious causes and prevent potentially life-threatening emergencies.
A less serious, self-limiting case of melena can occur in newborns two to three days after delivery, due to swallowed maternal blood.[citation needed]
Diagnosis
In acute cases, with a large amount of blood loss, patients may present with anemia or low blood pressure. However, aside from the melena itself, many patients may present with few symptoms. Often, the first approach is to use endoscopy to look for obvious signs of a bleed. In cases where the source of the bleed is unclear, but melena is present, an upper endoscopy is recommended, to try to ascertain the source of the bleed.[citation needed]
Lower gastrointestinal bleeding sources usually present with hematochezia or frank blood. A test with poor sensitivity/specificity that may detect the source of bleeding is the tagged red blood cell scan. This is especially used for slow bleeding (<0.5 ml/min). However, for rapid bleeding (>0.5 ml/min), mesenteric angiogram ± embolization is the gold standard. Colonoscopy is often first line, however.[citation needed]
Melena versus hematochezia
Bleeds that originate from the lower gastrointestinal tract (such as the
Etymology
The origin of melena is dated to the early 19th century via modern Latin, via Greek melaina (feminine of melas, black).[citation needed]
See also
References
- ^ MedlinePlus Encyclopedia: Bloody or tarry stools, retrieved 19 July 2010.
- ISBN 978-0-7020-5103-6.
- ISBN 9781438121031.
Iron supplements cause a grayish-black stool that should be distinguished from the black, tarlike stool that occurs from bleeding ulcer.
- ^ Dugdale, David (2009-11-01). "Bloody or tarry stools". National Institutes of Health. Retrieved 2009-11-30.
- ISBN 9780409900774.
Melena strongly suggests, and hematemesis confirms, that bleeding is of upper gastrointestinal origin…Peptic ulcer, the most common cause of gastrointestinal hemorrhage, should be pursued through questions about epigastric distress, the relationship of symptoms to food intake, and a history of peptic ulcer disease.
- ISBN 9780729541473.
- PMID 26508464.
- ^ ISBN 978-0-07-174889-6.