High Risk Samples


The ‘high risk’ refers to the danger of infection from accidental exposure to material which is known to be, or suspected to be present in specimens. The laboratories and people transferring samples require to know when such a risk is present so that appropriate extra precautions, which are required by the Health and Safety at Work regulations, may be used while investigations are processed, and during transport and storage of the samples.

It is the doctor’s responsibility to inform the laboratories of such a risk.

These special precautions apply to all specimens from patients known to be or suspected of being infected with the following pathogens which are in Hazard groups 3 or 4 of the Advisory Committee on Dangerous Pathogens (ACDP) categorisation of pathogens :

Hazard group 3 – for example Anthrax, Brucella, Salmonella typhi and paratyphi, Creutzfeldt-Jakob Disease (CJD) and E. coli 0157.
Hazard group 4 – for example viral haemorrhagic fever (Ebola, Marburg), Crimean Congo Haemorrhagic Fever (CCHF)

Since Anthrax remains a real possibility with injecting drug users (IVDU), ALL samples from these patients with suspected infection MUST be labeled as HIGH RISK on both the request and sample.

Where there is a suspicion of a viral haemorrhagic fever in someone with a febrile illness within 21 days of return from an endemic area (for example tropical Africa), the case must be discussed with the on call duty microbiologist BEFORE specimens are collected. Special transportation and handling precautions are required. Such samples must NOT be sent via the pneumatic tube.

Specimens from patients with suspected prion disease such as CJD present particular problems for pathology laboratories because of the difficulty in sterilising and disposing of infected materials. Only specimens that are vital for examination should be sent to the laboratories.

Where patients are known positive for M. tuberculosis , all microbiology and histopathology samples submitted from them should be identified with a HIGH RISK sticker on the request form and sample.

As CJD is designated as a category 3 agent, specimens must be “flagged” as high risk and the relevant clinical information should be included on the request form. Laboratories MUST be alerted before any specimens are sent on ‘known’, or ‘suspected’ cases of prion disease or from the ‘at risk’ patient group especially specimens from brain, CSF, and eye. This will allow for segregation of the specimens, and give staff time to put into place the necessary arrangements for disposal.

High risk specimens must be identified by a “Danger of Infection” or equivalent ‘high risk’ sticker on the request form and on the specimen container (specifying which infection, on the request form). Specimens should be placed within a bag labeled “High Risk” or “Danger of Infection”.

In the case of electronic requests the high risk sticker should be placed on the sample and the bag and the appropriate information added to the clinical details box.