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Medibot
Hyperemia vs Congestion in Pathology
Hyperemia versus congestion explains why a swollen, red organ can come from too much blood arriving or from blood that cannot leave. Hyperemia is an active process of increased arterial blood flow, while congestion is a passive process caused by raised venous hydrostatic pressure (the pressure of blood backing up in the veins). Pathologists use the difference to read organ changes such as pulmonary edema and nutmeg liver, and to tell short-term from long-term damage.