directorate of laboratory medicine1 sample handling malcolm dunlop directorate quality manager
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Directorate of Laboratory Medicine 1
Sample handling
Malcolm DunlopDirectorate Quality Manager
Directorate of Laboratory Medicine 2
Clinical Sciences Building 1
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Clinical Sciences Building 2
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Laboratory Departments
Typical DGH
• Clinical Biochemistry (Chemical Pathology)
• Haematology
• Histopathology
• Microbiology
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Laboratory Departments
Teaching hospital / tertiary referral• Clinical Biochemistry (Chemical Pathology)
• Haematology
• Histopathology
• Microbiology
• Immunology
• Virology
• Sub Fertility – associate department
• Cytology
• Others e.g. Genetics
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What constitutes a sample• Any biological material taken from a
patient for diagnostic, prognostic or therapeutic monitoring
• Under the new Human Tissues Act tissue includes
• blood • urine & other fluids• faeces • sweat • semen• tissue
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Infection risks• All samples must be considered to be
infectious
• Use of “Universal Precautions” handling
• Never assume any sample is “safe”
• Today’s symptoms may be tomorrow’s diagnosis of infection
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Phases of analysis• Pre-analytical (from the patient to the
lab)
• Analytical
• Post-analytical (from the lab to the notes)
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From the patient to the lab• What can (and does) go wrong
• Incorrect identification of patient
• Patient preparation – fasting, diet, supine, time, drugs.
• Sample poorly/ incorrectly taken
• Inaccurate timing
• Wrong type of sample
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From the patient to the labWhat can (does) go wrong?
• Incorrect container(s)
• Under-filling
• Mislabelling/ no labelling
• Incorrect storage/ transport (ice, warm, delay)
• Loss, breakage etc.
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The Patient• Do patients always disclose history?
• Confused
• Frightened
• In pain
• Want to help !!!
• Are previous diagnoses available?
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Quality
• Laboratories can only produce quality results on quality samples
• And on quality requests
• Rubbish In Rubbish Out
• Ideal sample mimics the in vivo state
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Requesting• Requested on PAS = electronic return
• Requested manually = NO electronic return
• Electronic/ manual mixed requesting = break in electronic record
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Results• Telephoned results are the most
unsafe method
• Electronic are safest and quickest
• Hardcopy reports must be filed as per instructions
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Blood collection• Ask patients to identify themselves
• When blood taken write all relevant details on collection tubes immediately
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Sample acceptance• Patient safety is of the utmost
importance
• Samples and requests MUST allow clear identification the patient
• Samples identified incorrectly will NOT be processed
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Sample acceptance• The sample MUST include patient’s:-
– Surname– Forename– Date of Birth or Hospital Number or NHS
number– Histology specimens MUST include
Hospital number
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Other information• SHOULD include
– Ward– Date of collection– Time of collection e.g. Cortisol
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Sample acceptance• Request form MUST contain
patient’s:-
– Surname– Forename– Date of Birth and/ or Hospital or NHS
number– Ward or clinic– Tests requested
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Samples for Blood Transfusion
• MANDATORY identification requirements– As previous plus signature and printed
name of requestor on form– Signature of person collecting the blood
on the sample tube(s) and on request form
– Date of request and of sample
• See Blood Transfusion Policy
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Venous blood sampling
Syringe Hybrid Evacuated
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Blood collection• Use the blood collection system in
use• Advantages over needle & syringe
– Higher quality sample– Minimises clotting mechanism– Produces correct blood to anticoagulant
ratio when properly filled– Easier– Quicker
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Sampling problems - blood• Inappropriate site – drip arm,
mastectomy, burns etc
• Timing
• Incorrect use of tourniquet
• Wrong container
• Incorrect order of draw
• Transportation
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Urine collection• 24 hour sample must include all urine
passed in this period
• If less than 24h, inform the lab
• Mid stream sample – self explanatory
• Early morning sample – often best
• Correct container type
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Urine samples• Incorrect timing
• Inappropriate for test required
• Sterility
• Volume
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Other considerations• Swabs for culture may need specific
transport media e.g. Chlamydia
• Blood cultures – special bottles & technique for taking the blood
• Tissue for Histology – fixative * Extreme care needed when using
formalin
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