This section is from the book "The Home Hand-Book of Domestic Hygiene and Rational Medicine. Volume 2.", by J. H. Kellogg, M.D.. Also available from Amazon: The Home Hand-Book of Domestic Hygiene and Rational Medicine, Volume 2.
This has also been described as a condition in which a part of the body contains too much blood. This morbid condition must evidently be of a local character, since the whole body could not be congested. Too much blood in one part necessarily implies too little in another part, unless, indeed, the patient be suffering from the condition known as plethora, in which the whole quantity of blood is abnormally increased and the usual symptoms of local congestion are extended to the whole system. The results of congestion and its accompanying symptoms vary greatly, according as it is active or passive in character.
Active congestion is characterized by an increased amount of arterial blood in an organ, the result of which may be temporary swelling or enlargement and pain, together with an increase of temperature and even redness in color. These symptoms are also all present in inflammation. That condition, as we shall show presently, is accompanied with other characteristic symptoms not found in simple congestion.
In passive congestion there may be swelling of the part, from the turgescence of blood or from the infusion of serum into the tissues, as in dropsy. If there is a change in color, the part will be dark and purplish, instead of bright red as in active congestion and inflammation; there may also be pain in passive congestion. If pain is present, it will be of a dull, heavy, continuous character, instead of acute, sharp, and lancinating, as is usually the case in active congestion. The causes of both active and passive congestion having already been given elsewhere, we do not need to delay on the subject here.