Introduction
Once you get stuck on a corner or bump your foot and there it is: the bruise. In most cases, the black-bluish discoloration, which doctors like to call a “haematoma”, disappears within a few days. But in some cases the bruise persists for weeks.
Sometimes it also occurs in places that seem unusual at first or that can even be dangerous, such as the eye and knee. A bruise is always a sign of blood leaking into surrounding tissue, preferably an already existing body cavity. But how exactly does a bruise occur, what happens in the body and what can be done about it?
Causes of bruising
A haematoma occurs when blood from a vessel passes into surrounding tissue. Every cell in our body needs to be supplied with oxygen and oxygen can only reach the cells via the bloodstream. This means that every cell in our body must be supplied with blood in order to survive.
So blood is everywhere in the body. It is transported by the blood vessels to the most remote corners of our body. The vessels are not all the same thickness.
From the largest vessel in the body, the aorta, to the fine capillaries in the eye, there are immense differences in size. The larger the injured vessel, the more blood passes into the surrounding tissue and the greater the bruise. But what causes a vessel to rupture?
In the majority of cases, this is due to external force. This can be a blow, a firm grip, but also an operation or an object you hit yourself on. The small capillaries have only a limited wall thickness, so that they burst if the pressure is too high.
This is not too bad, as they regenerate quickly. However, in the time until the vessel is closed – i.e. about 2-5 minutes depending on the size of the injury – blood enters the tissue. At first, the bruise still appears red – after all, the blood is stained red by the blood pigment haemoglobin.
After a few minutes to hours, however, the blood has already coagulated and now shines through the skin in dark blue. As the process continues, the coagulated blood is now broken down. This causes a renewed discoloration into the black/brown area.
Further enzymatic degradation causes the bruise to turn greenish and finally yellowish. Bleeding from larger vessels can be stopped by the body less easily and less quickly. There is a danger that the loss of blood has systemic effects.
The blood volume is 6-7% of the body weight. For a man weighing 80 kg, this means just under 6 litres of blood. In the case of a pelvic fracture, up to 4 litres of blood can be lost if the blood supply is not available – this is fatal for the person, as such a high blood loss can no longer be compensated.
With a normal bruise, however, there is normally no danger to life. Most bruises are caused by an injury. Falls, knocks or blows damage the tissue and cause a vessel to burst, whereupon blood leaks into the tissue and becomes colour-coded.
However, if a bruise occurs with no apparent cause, you should observe your body more closely. If bruises occur frequently, without an identifiable cause or the slightest minor trauma, the bruises could be caused by a serious disease. Possible examples are: Haemophilia Willebrand- Syndrome Blood coagulation disorder (sometimes familial, inherited) Leukaemia Torn muscle fibre Torn ligament or pulled ligament Sprain If bruises occur frequently without a recognisable cause, the family doctor should be consulted. – Haemophilia (blood disorder)
- Willebrand- Syndrome
- Blood coagulation disorder (partly familial, inherited)
- Leukaemia
- Torn muscle fibre
- Torn or strained ligament
- Sprain
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