Coffee ground vomiting
refers to a particular appearance of vomit
. Blood contains iron within heme
molecules in red blood cells
. When this iron has been exposed to gastric acid
for some time, it becomes oxidized
. This reaction causes the vomitus to look like ground coffee
. Coffee-ground vomitus is a classic sign of upper gastro-intestinal bleeding. A peptic ulcer
, for example, may bleed into the stomach and produce coffee-ground vomitus. When bright red blood is vomited, this is termed hematemesis
. Hematemesis, in contrast to coffee ground vomitus, suggests that upper gastrointestinal bleeding is more acute or more severe, or originates more proximally than the stomach: for example, in the esophagus due to a Mallory-Weiss tear
Oxidized blood from an upper gastrointestal bleed can also be excreted in stool. It produces tarry, blackened stools known as melena.
Coffee ground vomiting is due to haemolysis of the red blood cells causing haemosiderin deposits.