Severe contamination (during laparotomy for faecal peritonitis)

Old laceration (>12 - 24 hours; depends on amount of contusion)

Shock (of any cause but usually haemorrhagic)

Devitalisation (poor local tissue perfusion)

Foreign body (either external or known dead tissue)

Kinetic energy (in wounds caused by explosions; implies presence of dead tissue and foreign material)