Melaena, the term applied to the condition in which altered blood appears in the stools. If bleeding occurs into the alimentary canal, the action of the digestive juices upon the blood is such that its red colour is lost, and a black appearance is produced in the discharges which are passed per anum. The word melaena, which is derived from a Greek word signifying "black," is hence appropriately applied to the condition. Melsena may be due to hyperemia, ulceration, or new growth affecting the stomach or intestines. It occurs in malaria, purpura, and scurvy, and supervenes in cases of obstruction to the portal circulation due to liver disease or to other causes.