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📘 Why do bruises change colour as they fade?

Explain bruise colour changes through vessel leakage, hemoglobin breakdown, macrophage cleanup, biliverdin, bilirubin, and the limits of dating an injury by colour.

4
lessons
~20 min
to learn
Adults
level
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What you’ll learn

  1. The Mark Under The SkinExplain how a bruise begins as blood leaked from damaged small vessels beneath intact skin.A contusion is a local collection of leaked blood in soft tissue, whose appearance is filtered by depth and skin.
  2. Why The First Colour Is DarkConnect early bruise colours with red blood cells, hemoglobin, oxygen conditions, and light absorption.Early dark shades reflect concentrated blood products and changing forms of hemoglobin outside the circulation.
  3. The Cleanup Changes The PaletteDescribe how macrophages and heme breakdown products contribute to green and yellow stages.Immune cleanup transforms hemoglobin into pigments including biliverdin and bilirubin, changing the visible palette.
  4. Limits And The Short AnswerRecognize colour limits and state the complete fading mechanism.Bruise colours follow leakage, breakdown, and clearance; the sequence is real but not a precise clock.

Questions this course answers

What starts an ordinary bruise?

A contusion begins when injured small vessels leak blood into soft tissue without necessarily breaking the skin.

Put this simplified process in order.

The visible sequence follows leakage, breakdown, cellular processing, changing pigments, and removal, although the stages overlap in real tissue.

Why can a healing bruise look greenish or yellow?

Biliverdin is green and bilirubin is yellow; both can contribute to later bruise colours as heme is processed.

Why is bruise colour not a precise way to tell how old an injury is?

Depth, size, location, skin tone, blood flow, medications, injury force, and uneven pigment mixtures all affect appearance and healing speed.

Grounded in trusted sources

  • MedlinePlus Medical Encyclopedia, Bruise healing - series. https://medlineplus.gov/ency/presentations/100207_2.htm
  • MedlinePlus, Bruises. https://medlineplus.gov/bruises.html
  • MedlinePlus Medical Encyclopedia, Bruise. https://www.medlineplus.gov/ency/article/007213.htm
  • Macedo et al., Current and emerging methods for treatment of hemoglobin related cutaneous discoloration: a literature review. https://pmc.ncbi.nlm.nih.gov/articles/PMC7814147/
  • Hughes et al., The practical application of reflectance spectrophotometry for the demonstration of haemoglobin and its degradation in bruises. https://pmc.ncbi.nlm.nih.gov/articles/1770270/
  • Dunn et al., Natural History of the Bruise: Formation, Elimination, and Biological Effects of Oxidized Hemoglobin. https://pmc.ncbi.nlm.nih.gov/articles/PMC3671564/

Every Wunder lesson is built from real, reputable sources — never invented.

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