Haematemesis occurs when a person vomits blood. It can be due to causes in the mouth or nose (epistaxis or bleeding gums due to which the patient swallows his own blood, vomiting it later on), esophagus (ruptured varices,tears, esophagitis, bleeding disorders, carcinoma), stomach (ulcers, gastritis, carcinoma) and duodenum (ulcers, etc) and of course, bleeding disorders.
If the vomited blood is brown and granular (‘coffee-grounds’), it is because it has been digested by the stomach acids due to which the haemoglobin has been converted to acid haematin, imparting it the characteristic brownish color.
If the blood in the vomit is bright red, it has been directly extruded from the esophagus or if it came from the stomach or duodenum, was not retained within the stomach long enough to cause its digestion and thus alteration of color.
In both cases, blood clots can be present but are not specific or pathognomonic for any particular condition.
Causes of Haematemesis: