Clinical suspicion of non-accidental injury. CT scan performed as part of a full skeletal survey and child protection review. CT confirms subdural collections containing mixed density material. The high-density material is acute blood. Blood remains dense for up to 2 weeks when it is generally accepted that the vast majority of blood will have reduced in density to that approaching parenchyma.

Fluid of different densities within the subdural space may occur because of:

• blood of different ages
• acute blood mixed with CSF
• acute blood mixed with fluid in the subdural space