Melena is a medical term that describes the sign of blood per rectum, specifically dark stool that represents the passage of old, processed blood throughout the gastrointestinal (GI) tract as a result of overt bleeding from either upper or lower sources. This overt GI bleeding is different from microscopic bleeding, or fecal occult blood, which is usually referred to as occult GI bleeding. Melena can be erroneously considered an exclusive sign of lower GI bleeding (LGIB), which technically is a term used to denote hemorrhage from an intraluminal source distal to the ligament of Treitz. Melena, however, could also be the external manifestation of a pathologic disease process that indicates the presence of intraluminal hemorrhage from the upper GI tract. This is true when the bleeding takes place at a slow rate and with low volume. Alternatively, melena could also represent bleeding from the lower GI tract with the same criteria: slow or low volume. In any case, melena is macroscopic bleeding, that is, witnessed by the patient, by the caretaker, or healthcare professional and not to be confused with microscopic bleeding, either from the upper or the lower GI tract. On the other hand, melena can be caused by bleeding from a source in the GI tract not easily accessible by conventional endoscopic measures such as esophagogastroduodenoscopy or colonoscopy. When it is caused by bleeding from the small intestine distal to the ligament of Treitz and proximal to the ileocecal valve, not accessible by conventional endoscopy, it is referred to as obscure GI bleeding. Melena requires a critical approach to diagnose and treat the source of GI bleeding in a prompt manner, with particular attention to the possibility that the source of hemorrhage could be related to a malignant process and not only to a benign pathology. This is especially relevant as advanced age or other risk factors play a role in the presentation. Melena could be the result of various causes that ultimately require attention to detail, a high index of suspicion, and resuscitation measures that may lead to referral to a surgical specialist for definitive treatment with therapeutic endoscopy or surgical modalities. The recognition of melena as an expression of a potential surgical emergency is essential for patient’s survival and definitive management of the cause of the acute or chronic upper or lower GI bleeding in a short amount of time and in compliance with resuscitation protocols. This chapter will illustrate the tenets of melena diagnosis and management, including a practical surgical referral algorithm for primary care professionals who are exposed to this external manifestation of acute or chronic upper or lower GI bleeding.

Melena

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发表日期：

2025年

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Rodolfo J. Oviedo

摘要

Melena is a medical term that describes the sign of blood per rectum, specifically dark stool that represents the passage of old, processed blood throughout the gastrointestinal (GI) tract as a result of overt bleeding from either upper or lower sources. This overt GI bleeding is different from microscopic bleeding, or fecal occult blood, which is usually referred to as occult GI bleeding. Melena can be erroneously considered an exclusive sign of lower GI bleeding (LGIB), which technically is a term used to denote hemorrhage from an intraluminal source distal to the ligament of Treitz. Melena, however, could also be the external manifestation of a pathologic disease process that indicates the presence of intraluminal hemorrhage from the upper GI tract. This is true when the bleeding takes place at a slow rate and with low volume. Alternatively, melena could also represent bleeding from the lower GI tract with the same criteria: slow or low volume. In any case, melena is macroscopic bleeding, that is, witnessed by the patient, by the caretaker, or healthcare professional and not to be confused with microscopic bleeding, either from the upper or the lower GI tract. On the other hand, melena can be caused by bleeding from a source in the GI tract not easily accessible by conventional endoscopic measures such as esophagogastroduodenoscopy or colonoscopy. When it is caused by bleeding from the small intestine distal to the ligament of Treitz and proximal to the ileocecal valve, not accessible by conventional endoscopy, it is referred to as obscure GI bleeding. Melena requires a critical approach to diagnose and treat the source of GI bleeding in a prompt manner, with particular attention to the possibility that the source of hemorrhage could be related to a malignant process and not only to a benign pathology. This is especially relevant as advanced age or other risk factors play a role in the presentation. Melena could be the result of various causes that ultimately require attention to detail, a high index of suspicion, and resuscitation measures that may lead to referral to a surgical specialist for definitive treatment with therapeutic endoscopy or surgical modalities. The recognition of melena as an expression of a potential surgical emergency is essential for patient’s survival and definitive management of the cause of the acute or chronic upper or lower GI bleeding in a short amount of time and in compliance with resuscitation protocols. This chapter will illustrate the tenets of melena diagnosis and management, including a practical surgical referral algorithm for primary care professionals who are exposed to this external manifestation of acute or chronic upper or lower GI bleeding.