Haemorrhage, or bleeding, is the escape of blood from the blood vessels as a result of an injury or defect in the permeability of the vascular walls. Blood loss is a life-threatening condition, which necessitates prompt treatment, as the life of the injured person invariably depends on how fast the doctor can deal with the problem.
In terms of the mechanism, haemorrhage divides into:
• mechanical (disruption or erosion of a vessel);
• neurotrophic (impaired permeability of vessels as a result of vascular wall pathology, which can be secondary to various diseases - scarlet fever, scurvy, haemophilia etc).
The following types of haemorrhage are identified:
1) haemorrhage per rexin (as a result of mechanical damage to the vessel - a tear or rupture);
2) haemorrhage per diabrosin results from erosion of blood vessels (by a tumour, in tissue necrosis and in infections);
3) haemorrhage per diapedesin due to a defect in the permeability of the vascular walls.
Bleeding can also be classified as arterial, arteriovenous, venous and capillary. Parenchymal bleeding is a capillary type of bleeding from an organ like the liver.
Bleeding can also be external (when blood oozes outside the body) and internal (when blood accumulates in an enclosed space of the body or in the cavity of a hollow organ). Moreover, it can be occult, when diagnosed only by means of specific methods of investigation.
Traumatic bleeding is classified as follows:
• primary (results from an injury to a vessel);
• secondary (occurs if a clot breaks away from the vessel because of a rise in blood pressure or as a result of vascular spasm, in which case it is referred to as early secondary bleeding). On the other hand, late secondary bleeding is due to clot dissolution secondary to pyogenic infection or erosion of the vascular wall.