Loss of blood volume is initially counteracted by intravenous saline and later by typed and cross-matched blood transfusion. These are caused by blockage of liver veins in liver disease, usually from alcohol. It is arterial bleeding and can be severe. Cancer of the colon usually causes a slow non-visible loss of blood, but the loss can be massive. Bleeding can be stopped under direct vision by electro or heat coagulation through an endoscope.
Correct treatment depends on a carefully made, accurate diagnosis.
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