Compared with watery diarrhoea, bloody diarrhoea generally lasts longer, is associated with more complications, is more likely to adversely affect a child's growth, and has a higher risk of death. Bloody diarrhoea in a young child is usually a sign of a serious invasive bacterial infection of the bowel. Pathogens that cause bloody diarrhoea may also cause diarrhoea without visible blood, but such episodes are less severe, generally resembling diarrhoeal disease caused by non-invasive pathogens. The presence of visible blood is, thus, a convenient and reliable indicator of severity. When these steps are followed, most episodes of bloody diarrhoea resolve rapidly and many serious consequences are avoided.
Bloody diarrhoea refers to a diarrhoeal episode in which the stools contain visible red blood.
It is the preferred term to describe this problem. Dysentery has the same meaning as bloody diarrhoea. Although sometimes used to describe bloody diarrhoea that is associated with fever, abdominal cramps, rectal pain and mucoid stools, these features do not always accompany bloody diarrhoea, nor does their presence or absence necessarily define its etiology or determine how it should be treated. Shigella are the most important cause of bloody diarrhoea among young children in developing countries. Episodes of bloody diarrhoea caused by other bacterial pathogens occur less frequently than shigellosis, are usually less serious, and their cause is often difficult to determine except in research laboratories.