A skin contusion (bruise) is a closed, blunt injury that ruptures small subcutaneous vessels without breaking the skin. Blood leaks into surrounding tissues, producing a predictable sequence of local and sometimes systemic changes.

1. Immediate pain and tenderness
   Nociceptors are activated at the moment of impact; the area is sore to touch and may throb with movement or pressure.
2. Colour evolution
   Erythema appears within minutes, followed by reddish-purple or dark-blue discoloration as blood accumulates. Over 5–10 days the pigment breaks down, passing through blue, green, yellow and finally light-brown before fading .
3. Swelling and induration
   Plasma exudation and blood clot formation create a palpable, slightly raised plaque; larger collections produce a fluctuant haematoma.
4. Warmth and localized fever
   Acute inflammation increases skin temperature; however, spreading heat, red streaks or purulent discharge signals secondary infection.
5. Functional limitation
   Contusions near joints or muscle bellies reduce range of motion and strength because of pain-induced guarding; weight-bearing on a bruised limb is often avoided.
6. Resolution timetable
   Most superficial bruises resolve in about 2 weeks. Hematomas, bone bruises or lesions in patients on anticoagulants may persist for >1 month and leave transient post-inflammatory hyperpigmentation.
7. Warning signs
   Persistent expansion, severe pain out of proportion to appearance, rapid colour change to dusky purple, or associated numbness mandates evaluation for compartment syndrome, necrotising fasciitis or major vessel injury.