directorate of laboratory medicine1 sample handling malcolm dunlop directorate quality manager

Directorate of Laboratory Medicine 1

Sample handling

Malcolm DunlopDirectorate Quality Manager

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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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