Previously, doctors only had to report cases of gun crime
Doctors in the UK should tell police every time they treat a victim of gun and knife crime, new guidelines from the General Medical Council will state.
They are also told they can breach patient confidentiality by giving police information if they believe a crime has or will be committed.
If a patient is diagnosed with a genetic disease doctors will be able to tell relatives, without consent.
The revised guidance on confidentiality will be published on Monday.
It is the first time doctors have been explicitly told they should report all knife crime as previously they only had to report patients with gunshot wounds.
It is hoped this will help police get better statistics on where and when violent crime is taking place.
'Not entirely innocent'
Doctors will also be asked to decide whether they should breach confidentiality and pass on the patient's details to the police if they suspect a crime has or will be committed.
Jane O'Brien, head of standards and ethics at the GMC, who drew up the guidance said: "This is mostly going to be used in A&E, for example, where the injury could be the result of gang culture, with gunshot wounds or knife injuries and the victim may also not be entirely innocent.
"In which respect they might not want the police to be involved and might be thinking about revenge attacks. Normally you would expect the doctors to go along what the patient wanted in these circumstances."
But she said doctors should still decide on a case-by-case basis.
Tunji Lasoye, lead consultant, emergency department at Kings College Hospital, said it was important for doctors to play a part in protecting the public.
"The guidance will help doctors to recognise how to report injuries resulting from violence while making the care of their patient their first concern."
The guidelines also say when a patient is diagnosed with a genetic disease, including some forms of cancer, doctors will be obliged to inform relatives about potential risks to their health.
The GMC said in cases where the information would benefit others the duty to protect them should outweigh the individual's right to privacy.
It will allow them to explain risks to health in situations involving family breakdown or children who have been adopted.
Dr Henrietta Campbell, who chaired the GMC's working group on confidentiality, said: "This guidance makes clear that , in the first instance, doctors should explain to a patient if their family might be at risk of inheriting a condition.
"In those circumstances, most will readily share information about their health. However if a person refuses, it is the responsibility of the doctor to protect those who may be at risk."
The British Medical Association said it broadly supported the new guidance on confidentiality.
Chairman of its medical ethics committee, Dr Tony Calland, said: "Ultimately confidentiality is the cornerstone of the doctor-patient relationship and it should only be breached in the rare circumstances where it is clearly in the public interest to do so."
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