Children who need hospital treatment for injury can develop post-traumatic stress, and experts have developed a simple test for it.
Children can be affected by PTSD
It could help find those whose psychological scarring has passed unnoticed by doctors.
Post traumatic stress disorder (PTSD), first highlighted in the 1980s, is now widely accepted as a genuine condition to which children are particularly vulnerable.
One study suggested that one in five children taken to hospital following a road accident developed the disorder - even if their injuries were not severe.
Symptoms of PTSD include recurring distressing images of the traumatic incident, both in dreams and while awake, coupled with an unwillingness to think about what happened, and general "jumpiness".
If left untreated, these feelings can persist for years, and a child's schooling and home-life can suffer.
A study of teenagers who had been involved years earlier in a cruise ship disaster in the Mediterranean found that 17% were still displaying clear signs of PTSD.
Researchers from the Children's Hospital of Philadelphia have devised a questionnaire that could be given to parents and children in an A&E setting.
It is designed to pick out those most likely to go on to develop PTSD.
Questions for children included whether they had been separated from their parents, or felt very afraid.
The parents - also at risk of PTSD after their child is hurt - were asked if they felt helpless, or seen the moment their child was injured.
Of the children who screened "positive" for PTSD risk, a quarter went on to develop full symptoms over the next few months.
Only one in 20 of those who screened "negative" developed PTSD.
Even more pronounced results were obtained from the parents.
Dr Flaura Winston, one of the study authors, said: "Until now, health care providers did not have a simple way to tell, early on, who could be at risk of PTSD after a child injury.
"We hope that acute care physicians can use this screening tool to help determine who should be referred for psychological evaluation and intervention."
Professor William Youle, from the Institute of Psychiatry at Kings College, London, has carried out extensive research into PTSD in children.
He said that it was hard to foresee busy A&E doctors having time to devote to psychological screening when they were trying to treat physical injuries.
He said: "Normally the A&E would write to the child's GP telling them what had happened, and it would be nice to think that the GP would then call in the child a couple of weeks later to see how they were getting on.
"Unfortunately, that is not routine at the moment."
He said that effective treatments did now exist for children with PTSD, which would be more effective if the problem was spotted early.
"The situation in the UK is far better than before - we have been preaching and teaching about this condition whenever we can.
"However, there are still people who think that children are pretty resilient, or that they will 'grow out of it' - and that isn't necessarily the case."
The study was published in the Journal of the American Medical Association.