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2007 Specimens for Clinical Laboratories Policy
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Specimens for Clinical Laboratories

Page updated 30 April 2007

Specimens for Clinical Laboratories

Key Points

Ensure all specimens are labelled correctly

The freshness of the specimen determines its usefulness, so get all specimens to the laboratory as soon as possible

All specimens are potentially dangerous so should be bagged and must be transferred to laboratories in proper rigid containers

Contaminated and unlabelled specimens will be discarded

Label specimens 'HIGH RISK' when appropriate

Serum should be saved in Virology for those having major cardiac, cranial, or abdominal surgery

Quality

The usefulness of a specimen collected for laboratory investigation depends on the appropriateness of the specimen and the time it takes to reach the laboratory. Staff in the laboratories are always happy to give advice about specimens required for investigations, and once taken, every effort must be made to ensure that the specimen reaches the appropriate laboratory as soon as possible. When problems with internal transport are encountered, please refer them to the Chief MLSO for your laboratory.

UNLABELLED SPECIMENS WILL NOT BE PROCESSED.

SPECIMENS SHOULD BE LABELLED WITH THE PATIENT'S NAME IMMEDIATELY AFTER THEY HAVE BEEN TAKEN.

Specimens must be sent in a plastic bag, preferably with the request form attached and should be transported in a rigid container. There are strict regulations about the packing of specimens for postage so this must be done in the laboratory. The request forms at UCLH carry an integral plastic bag designed to contain the specimen safely. Please use only these forms, and follow the sealing instructions carefully. Otherwise send all specimens in a plastic bag. Make sure that no request form is ever in contact with a specimen, and that only the specimens appropriate to that patient are placed into the bag. Do not use pins or staples to hold forms together. If a paperless system is used, it is even more important to label the specimen properly and to indicate the tests required on the specimen.

All the relevant information requested on the forms must be given to ensure specimens are correctly processed.

Infection Hazards

All samples in all laboratories are treated as containing virulent organisms.

Specimens from patients known to have blood borne virus infections must be labelled "High Risk" (Guidance in "HIV and the Practice of Pathology". Royal College of Pathologists, 1995). However, all specimens must be treated by portering and laboratory staff as a Danger of Infection. It is most important that specimens are transported safely. Lids should be firmly tightened. Ensure that forms are properly filled in and place the specimen in the plastic wallet attached to the form. Do not use paper-clips, pins or staples or attach anything to a request card. All leaking or contaminated or broken specimens will be discarded.

The greatest danger of infection to laboratory staff comes from the specimens. This danger stems largely from specimens which have had clinical material spilt on the outside of the container, which may have been wiped "socially" clean. This may remove evidence of contamination but does not remove the risk of infection. When clinical material contaminates the outside of a specimen container, the specimen should be discarded on the ward.

Inevitably occasional specimen containers will leak. They should not be sent to the laboratory because this may lead to contamination of the porter, of the environment and of other specimens. Leaking specimens which arrive in the laboratory, except in very exceptional circumstances, will always be without immediate consultation. Further specimens will be requested but there will be a delay for the patient. When a specimen is seen to be leaking in a ward or department, if you are unable to deal with it safely, please consult the laboratory.

Haematology and Biochemistry

Specimens for haematological and biochemical investigations will be almost exclusively blood specimens. The problem is choosing the correct blood collection tube.

Bacteriology

Specimens for bacteriological investigations must be adequate. Delays in reaching the laboratory may result in death of some organisms or multiplication of others so that the number found in the specimen is meaningless. This is particularly important for urine specimens.

When aspirated pus, body fluids or faeces are available, do not use swabs. It is always better to send the original specimen in a sterile pot.

Always place a swab in appropriate transport medium. The transport media for bacteria, viruses and Chlamydia are different. When in doubt about which to use, please consult the laboratory. Eye swabs (for ophthalmia neonatorum), nasal swabs (for pertussis) and screening swabs (for staphylococci, etc) are best seeded directly onto fresh culture medium and are best taken by an ICN or a microbiologist after consultation.

Virology

Specimens for Virology fall into three types:

1. Culture and isolation of viruses: Special viral transport medium (VTM) is available. This preserves the viability of viruses but contains antibiotics to kill bacteria and fungi. VTM is useful for sensitive enveloped viruses (eg. herpes viruses) but not necessary for enteroviruses in stools, which can be sent untreated.

2. Antigenic and morphological identification of viruses: Clotted blood samples, faecal samples, fluids from ulcers or vesicles are required. Please consult the laboratory.

3. Serology: Serum samples (clotted blood) are required. Please use the correct request forms and send one form for each request. The serum sample will be divided in the laboratory.

Parasitology

"Hot stools" for amoebae should arrive in the laboratory within one hour of being passed. After this time the chances of seeing amoebic trophozoites will diminish rapidly. (The stools do not have to be kept warm).

Delays beyond 48 hours can result in parasite eggs in faeces hatching and the larvae disappearing from the sample. Similarly, urine samples for schistosome eggs need to be delivered to the laboratory quickly or in formalin to prevent hatching.

Blood films for malaria parasites should be made within two hours of phlebotomy. Later on, the morphology of the parasites may change so that identification and speciation are more difficult.

Special Infection Risks

Specimens from patients known to have blood borne virus infections must be labelled "High Risk" (Guidance in "HIV and the Practice of Pathology". Royal College of Pathologists, 1995). However, all specimens must be treated by portering and laboratory staff as a Danger of Infection.

Specimens from patients with suspected viral haemorrhagic fever must not be sent with the portering service. Transport must be agreed by Control of Infection Officers and specimens will carried by Microbiologists/Virologists.

Summary

 

Save Serum Policy

In view of the risks of patients acquiring blood borne viruses during surgery either from blood transfusion or from a member of the operative team, it is wise to save a sample of serum before such procedures. This should be saved at least for one year, preferably indefinitely, because of the long incubation of some of these infections. The serum would only be recovered and tested in the event of a possible acquisition incident.

 

Management of Specimens

Objectives

a. To collect an adequate amount of fluid un-contaminated from any other source. To preserve any organisms that are present.

b. To ensure that the specimen is correctly labelled and despatched to laboratory with complete request information.

c. To transport the specimen (and request form) to the laboratory safely with the minimum of delay.

Or

d. To store specimen in suitable conditions if delivery is delayed.

 

 

References

Schaffer SD , Garzon LS, Heroux DL. Korniewicz DM. Infection prevention and safe practice. 1996 Mosby , New York

Health Services Advisory Committee. Safety in Health Service laboratories. 1991. Also Health and Safety Commission. Safe working and the prevention of infection in clinical laboratories- model rules for staff and visitors. 1991 Department of Health, London

Packaging Requirements. Royal Mail Guidance 1999 UN 602