1. General considerations
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All specimens pose a potential infection risk therefore all standard precautions must be adhered to for collection, handling and transporting of all specimens to reduce the risk of healthcare associated infection. |
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All clinical staff responsible for handling specimens should have a responsibility and duty for the safe collection, labelling, handling and transporting of specimens. |
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All samples and accompanying paperwork must be transported in such a way as to maintain patient confidentiality at all times. They must never be left unattended in a public area. |
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The following information is required as a minimum and care is needed to ensure it is accurate ● Name of patient- last name and first name. ● Date of birth. ● Hospital Number. ● Team/ward location. ● Consultant name. ● Tests requested and relevant clinical details. ● Time of collection. ● Signed by requesting clinician with printed readable name of clinician and contact details. |
2. Venipuncture
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Make sure to collect the blood properly as the results can be misleading and inaccurate. |
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Follow the following techniques to prevent hemolysis. ● Mix all tubes with anticoagulant additives gently (vigorous shaking can cause hemolysis). ● Avoid drawing blood from a hematoma; select another draw site. ● If using a needle and syringe, avoid drawing the plunger back too forcefully. ● Make sure the venipuncture site is dry before proceeding with draw. ● Avoid a probing, traumatic venipuncture. ● Avoid prolonged tourniquet application (no more than 2 minutes; less than 1 minute is optimal). ● Avoid massaging, squeezing, or probing a site. ● Avoid excessive fist clenching. If blood flow into tube slows, adjust needle position to remain in the center of the lumen |
3. Blood Culture sampling
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Timing: As soon as possible after illness onset and ideally before initiation of antimicrobial therapy. |
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Collection technique: ● Use aseptic technique (Use antiseptic skin preparation, sterile eye towel, sterile gloves). ● Blood collected from single site is seldom appropriate. ● Always collect from two sites: Either percutaneous, central venous catheter, dialysis catheter or two different percutaneous sites. ● Amount: Volume of samples for blood culture depends on the type and size of culture bottle. Volume is generally taken in a ratio of 1:9 (i.e., 1ml blood for 9 ml broth volume). ● Label the bottle appropriately. All culture samples should reach lab within 30 mins of collection and processing should be started or else there will be less yield in culture. |
4. Urine Culture sampling
Urine Specimen should be always be sent for Routine examination, microscopic examination whenever it is planned for urine culture.
Collection technique
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Midstream Clean Catch Specimens ● The initial stream of the voided specimen should be discarded since the initial urine flushes urethral contaminants. ● It is the subsequent midstream sample that should be sent to the laboratory. |
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Collection from urinary Catheter ● Never obtain urine specimen from a catheter bag. ● Wash your hands, prepare equipment, and apply personal protective equipment. ● If taking a specimen from a sampling port, apply a clamp approximately 3 inches below the level of the sampling port. This allows urine to collect above the clamp so that a sample can be obtained. ● Clean the sampling port with alcohol and scrub for 15 seconds. ● Stabilize the tubing by holding it below the level of the sampling port. ● Insert the syringe tip into the sampling port. ● Aspirate at least 10 mL of urine and disconnect the syringe. ● Put the urine into a sterile specimen container, avoiding contact between the syringe and the cup. |
5. Sputum Expectorate sampling
Approaches used to improve the quality of the specimen obtained include
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Educate the patient about the difference between sputum and oral secretions. |
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Obtaining the specimen prior to antibiotic treatment. |
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Rinsing the mouth prior to expectoration. |
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No food for one to two hours prior to expectoration. |
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Inoculation of the culture media immediately after the specimen is obtained or immediately after prompt transport to the microbiology lab. |
6. Deep Tracheal Aspirate sampling
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Wear surgical cap, mask; scrub hands; wear sterile gown and sterile gloves. |
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Arrange all articles in a dressing set: 50 ml syringe with 50 ml sterile NS, 12Fr Suction catheter, mucus extractor, Catheter mount. |
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Preoxygenate the patient. |
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Attach sterile catheter mount into the endotracheal tube/tracheostomy tube and let the assistant help you in attaching the other side to ventilator. |
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Carefully pass the suction catheter through the catheter mount by opening its tip into the trachea. |
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Length of the catheter should be below the endotracheal tube/ tracheostomy tube. |
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Instill 50 ml Sterile NS into the trachea through the suction catheter. |
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Attach mucus extractor to the suction catheter. |
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Apply suction to aspirate the sample into the mucous extractor. |
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Collect the specimen through an endotracheal tube/ tracheostomy. |
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Send Deep Tracheal Aspirate for Gram stain and Culture both. |
7. Broncho-Alveolar Lavage (BAL) sampling
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Due to the invasive nature of BAL sampling the decision about whether to perform BAL should be based on the clinical judgement of the treating clinicians. |
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Timing: BAL samples may be obtained at any time during the clinical course but may be most informative if obtained prior to initiation of antimicrobial or steroid therapy. If antibiotics or steroids have been initiated course, duration and timing relative to BAL should be noted. |
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Sample collection: Complete aseptic technique (Use surgical cap, mask; scrub hand; sterile gown and sterile gloves. Collect samples in sterile containers. BAL fluid should undergo gram stain and culture. |
8. Cerebrospinal fluid sampling
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Complete aseptic technique (Use surgical cap, mask; scrub hand; sterile gown and sterile gloves. Whole body drape should be used. |
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Four samples of CSF should be collected into clearly labelled sterile containers, which indicate the sequence order of sampling. Additional sample of CSF is collected if needed. |
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Properly label the sample and send it to laboratory for processing within half an hour of collection for biochemistry and microbiological analysis. |
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Blood samples for total protein and glucose must be taken at the same time of lumbar puncture. |
Further Readings:
1. World Health Organization. (2010). WHO guidelines on drawing blood: best practices in phlebotomy. World Health Organization.
2. Ezzie, M. E., Aberegg, S. K., & O'Brien Jr, J. M. (2007). Laboratory testing in the intensive care unit. Critical care clinics, 23(3), 435-465.
3. Harvey, M. A. (1999). Point-of-care laboratory testing in critical care. American Journal of Critical Care, 8(2), 72.
4. Hall, J. R. (1990). Critical-care medicine and the acute-care laboratory. Clinical chemistry, 36(8), 1552-1556.
