Rare diseases · Sign or symptom
Melena
HP:0002249
What it means
The passage of blackish, tarry feces associated with gastrointestinal hemorrhage. Melena occurs if the blood remains in the colon long enough for it to be broken down by colonic bacteria. One degradation product, hematin, imbues the stool with a blackish color. Thus, melena generally occurs with bleeding from the upper gastrointestinal tract (e.g., stomach ulcers or duodenal ulcers), since the blood usually remains in the gut for a longer period of time than with lower gastrointestinal bleeding.
Rare diseases that can present with this16
Sometimes5–29%
10- Acquired von Willebrand syndrome
- Caroli syndrome
- Congenital dyserythropoietic anemia type III
- Crimean-Congo hemorrhagic fever
- Fetal and neonatal alloimmune thrombocytopenia
- Multifocal lymphangioendotheliomatosis-thrombocytopenia syndrome
- Multiple endocrine neoplasia type 1
- Neuroendocrine tumor of stomach
and 2 more in this range
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Black faeces · Black feces
Tracking symptoms like this for someone? Eleplan keeps symptoms, diagnoses, medications and every specialist in one plan.
Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.