Specimen collection part 3 - collecting a stool specimen
This article, the third in a six-part series on specimen collection, explains how to collect a stool specimen
Dan Higgins, RGN, ENB 100, ENB 998, is senior charge nurse in critical care, University Hospital Birmingham.
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Collecting a specimen is often a first crucial step in determining diagnosis and the mode of treatment (Dougherty and Lister, 2004). In all aspects of specimen collection the process must be one that reduces health and safety risk to all groups of staff handling the sample and one that reduces the risk of erroneous data/results.
Collecting a stool specimen
Stool specimens should be submitted for microbiological analysis from all patients in whom a diagnosis of gastrointestinal infection is suspected, as this process can identify the origin of any infection, be it bacterial, parasitic or viral.
Stool specimens should also be sent for microbiological analysis whenever patients present with diarrhoea of potentially infectious aetiology (Department of Health, 2003).
A stool specimen is required to diagnose Clostridium difficile, an infection associated with antibiotic use, which causes significant morbidity and mortality. It is a significant cause of antibiotic-associated diarrhoea, particularly in the frail and elderly. It can also be the result of cross-infection from another patient.
Stool specimens may be required for non-microbiological testing to detect the presence of other substances, for example occult blood. They are also collected for use in the national screening programme for colorectal cancer introduced in May 2006. Generally patients themselves collect this specimen at home and send it in the post to the screening unit on a special card.
Laboratory data should complement basic specimen analysis. The stool characteristics should be analysed. Many tools are available to classify stool types, these should be used as organisational policy. The most widely used is the Bristol Stool Chart, which classifies stools into seven groups from hard through to watery.
Stool aroma should also be documented as certain organisms may have a particular aroma, for example C. difficile. Frequency of diarrhoea should be noted and accounted for in any fluid balance calculations.
Recommendations regarding the timing of specimen collection may vary, particularly when looking for specific organisms. The nurse should refer to organisational policy or contact the microbiology service for advice. Specimens may also be required following a course of treatment for a specific infection, for example C. difficile. Again, microbiological advice should be sought for timing.
Any specimens should be sent to the laboratory immediately. This may not be practical in some situations, thus special procedures such as refrigeration (in a designated specimen fridge) may be required. Again, local policy will dictate.
The independent patient
For the independent patient who is able to obtain their own specimen, optimising specimen quality and reducing the risk of any potential cross-infection depends on patient education.
The patient should be encouraged to defecate into a clinically clean receiver, for example a bedpan, and taught how to collect the specimen using the stool pot.
If the specimen is being obtained in the community setting, cling film can be used as a ‘trap’ placed strategically over the toilet to gather it. Emphasis should be given to ensuring good hand hygiene, disposal of waste and decontamination following the procedure.
The nurse needs to be aware that the patient may find the procedure of collecting a specimen embarrassing and all attempts must be made to optimise dignity.
The following equipment should be gathered before taking the specimen:
- Disposable apron and gloves;
- Clinically clean bedpan or disposable receiver;
- Stool specimen pot, usually with an integral ‘spoon’ attached to the pot lid;
- Appropriate documentation.
- Obtain informed consent, provide education, and reassurance as required (Fig 1).
- Wash hands using soap and water and then dry them thoroughly.
- Apply gloves and apron.
- Ask the patient to defecate into a clinically clean bedpan or receiver, provide assistance as necessary. Using the ‘spoon’ provided, scoop up stool (Fig 2).
- If the patient has been incontinent, a sample may be obtained from bedlinen or pads; try to avoid contamination with urine (Fig 3).
- Using the ‘spoon’ that is provided, scoop up enough stool in order to fill approximately one-third of the container (usually greater than 10ml) (Fig 4).
- Apply specimen lid.
- Attend to patient hygiene as required.
- Dispose of gloves/apron, wash hands and dispose of waste (Fig 5).
- Complete the appropriate documentation, make a note of any characteristics of the specimen in the patient’s notes, for example colour, consistency or any particular aroma (Fig 6).
- Dispatch the specimen in accordance with organisational policy.
Department of Health (2003) National Clostridium Difficile Standards Group: Report to the Department of Health. www.dh.gov.uk
Dougherty, L., Lister, S. (2004) The Royal Marsden Hospital Manual of Clinical Nursing Procedures (6th ed). Oxford: Blackwell Publishing.
This procedure should be undertaken only after approved training, supervised practice and competency assessment, and carried out in accordance with local policies and protocols.