What makes a bruise purple yellow brownish

Why do blue spots change color?

Bruises - called hematomas in medicine - are part of everyday life for many of us. But why do they change color as they heal?

Overlook the coffee table and it happened - only a short time later a bruise adorns the shin. The naming is not entirely appropriate here, however, because: The hematoma not only glows in blue, but also in all variations from red, purple to brown through green and yellow.

The explanation for this is simple: In the case of a hematoma, pressure from the outside - for example, a bump on a nasty desk edge - causes many small blood vessels (capillaries) under the skin to burst. If the skin itself is not injured, the leaking blood will collect underneath. This will initially make a reddish spot visible through the skin.

Decomposition products cause the stains to vary in color

Gradually, the accumulated blood coagulates: the stain slowly shows a dark red, purple, bluish color. The body then begins to break down the leaked blood and its components.

One of those components of blood is hemoglobin, which is responsible, among other things, for the red color of our blood. In the case of a hematoma, this is broken down by enzymes in different processes. The resulting degradation products cause the different colors. These include:

  • Brown-black (choleglobin and verdoglobin)
  • Dark green (biliverdin)
  • Yellow-brown (bilirubin)

Bruises: Healing process about two weeks

These breakdown products are gradually excreted from the body until the stain disappears. The healing process takes about two weeks - it cannot be accelerated. However, by cooling immediately after a mishap, the spread can be contained because it constricts the blood vessels and less blood can leak out.

Important: In the event of major hematomas in connection with an accident, a fall while exercising or severe pain, a doctor should be consulted in order to rule out major injuries.

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Katrin Derler, BA
Editorial editing:
Elisabeth Mondl, Dr med. Kerstin Lehermayr

Updated on:

Hirner et al .: Surgery. Thieme Verlag, 2nd edition, 2008

Horn: Human biochemistry, textbook for medical students. Thieme Verlag, 6th edition, 2015

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