Hematemesis (synonyms: Vomiting of blood; vomiting of hematin; vomiting of coffee grounds; ICD-10-GM K92.0: hematemesis) describes vomiting of red or coffee-ground (black-brown) blood. The latter is caused by the presence of hematin. This is formed when hemoglobin comes into contact with gastric acid. The color change is due to oxidation of iron in hemoglobin.
Hematemesis can be a symptom of many diseases (see under “Differential diagnoses”). Usually, the cause is found in the esophageal (food pipe) or upper gastrointestinal tract (OGIB, upper gastrointestinal bleeding)/gastrointestinal tract.
Course and prognosis: Hematemesis is a medical emergency. The initial focus is to stop the bleeding. The course and prognosis depend on the cause as well as the degree of blood loss sustained.