Congestion

Congestion. The undue accumulation of blood in any part of the body may be brought about by increased supply, through dilatation of the arterioles (active congestion), or by obstruction to the return of blood from the part (passive congestion). Active congestion may be regarded as the early stage of inflammation (q.v.). Passive congestion may arise directly from venous obstruction, or from interference with the general circulation, leading to impaired power of effecting the natural transmission of the blood through the various organs and capillary systems of the body, and to its accumulation in dependent parts.