Sample Handling

Question 1

What are the different types of specimen handled within diagnostic and research labs?

Answer 1

Blood
Urine
Swabs
CSF
Needle biopsies
Bone
Tissue
Pus from absess
Non-sterile fluids

Question 3

Green top tube - what test?

Answer 3

Clinical biochemistry - electrolyte profile, bone profile, liver function tests, CRP

Question 4

Green top tube - what additive?

Answer 4

Lithium heparin - prevents clotting and coagulation of blood

Question 5

Green top tube - what sample?

Answer 5

Blood - plasma

Question 6

Yellow top tube - what additive?

Answer 6

Clot activator
Promotes clotting of blood. The sample must be given time for clot activator to take effect before centrifugation

Question 7

Yellow top tube- sample?

Answer 7

Blood - serum

Question 8

Yellow top tube - use?

Answer 8

When lithium heparin samples are not suitable - eg lithium, serum protein electrophoresis

Question 9

Separator gel - why used in green and yellow top samples?

Answer 9

Gel forms a barrier between 2 layers ie red blood cells and serum plasma. The gel prevents mixing. Increases stability of the sample

Question 10

Purple top - what additive?

Answer 10

K3 EDTA - irreversible anticoagulant
Chelates calcium, preserving RBC morphology

Question 11

Purple top tube - sample?

Answer 11

Whole blood

Question 12

Purple top tube - use ?

Answer 12

Most common in clinical haematology
Full blood count, ESR and also used in clinical biochemistry for HbA1C

Question 13

Blue top - additive?

Answer 13

Sodium citrate
Binds calcium to prevent clotting but is reversible.

Question 14

Blue top - sample?

Answer 14

Whole blood

Question 15

Blue top - use?

Answer 15

Within clinical haematology
D-Dimer
Pro-thrombin time

Question 16

Grey top - additive?

Answer 16

Fluoride oxalate
Inhibits glycolysis

Question 17

Grey top - sample type

Answer 17

Mostly plasma but also CSF and fluids

Question 18

Use of grey top

Answer 18

Measurment of glucose

Question 19

Microbiology sterile container - additive

Answer 19

None.
Purpose is sterile environment to transport samples

Question 20

Microbiology sterile container sample type?

Answer 20

Various fluids - sputum/ brain fluid
Use is respiratory culture eg

Question 21

Charcoal microbiology swab

Answer 21

Contains charcoal which mops up antibiotics. Use eg gonorrhoeae

Question 22

Amies gel microbiology swab

Answer 22

Contains Amie’s gel which prevents sample drying out and maintains anaerobic environment.
Example of use is for group B strep

Question 23

Microbiology growth bottles

Answer 23

Additive is growth mixture which allows bacteria to grow
Sample is blood and is used in blood cultures

Question 24

How do samples get to lab?

Answer 24

Hospital porters - every few hours collect samples from ward from inpatient request.

Pneumatic tube system - PTS - only used for urgent samples and connects ward to lab.

Van collection - collects samples from GPs and satellite hospitals. Collection several times a day. Most common

Question 26

Sample transport considerations

Answer 26

Properly sealed Hazard group 3 samples packaged separately with warning label - can’t do PTS. Eg HIV Unrepeatable samples always sent via porter.

Question 27

Pre analytic processing of samples post transport

Answer 27

Sorted and prioritised into urgent, inpatient and routine. Any labile samples that require immediate prep should be immediately actioned

Question 28

Urgent based upon what? In pre analytical sorting

Answer 28

What type of test is requested eg troponin in heart attack The source eg emergency dep Clinical need Red flags

Question 29

Sample specimen reception (checking) post sorting

Answer 29

Samples checked to ensure The sample type is correct from test requested Details sufficient on form and sample Details match on form and sample - minimum acceptance criteria Any errors? Form and sample given unique accession number

Question 30

Minimum acceptance criteria on sample

Answer 30

On sample Need H+C number Patient full name DOB Name of staff taking sample

Question 31

Minimum acceptance criteria on request form

Answer 31

On request form Full name H+c number DOB Sex, date and time of collection Consultant name HCP code of consultant Source Test requests Specimen type and site Name of staff taking sample

Question 32

What happens post checking details and MAC?

Answer 32

Test requests are put on the lab info managment system A unique accession number is linked to patient info and test requested

Question 33

Examples of unrepeatable samples?

Answer 33

Timed samples Histopathology samples CSF samples

Question 34

Post sample checking what happens?

Answer 34

Specimen prep for analysis Eg centrifugation for biochemistry Slides prepped for histo/cyto chemistry Inoculation/plating for microbiology

Question 35

Sample storage - plasma/serum

Answer 35

48h after final report

Question 36

Blood films storage

Answer 36

7 days after final report

Question 37

Histology slides storage

Answer 37

10 years

Question 38

Monitoring of samples in storage

Answer 38

Samples must be stored under correct conditions Eg RT, refrigerated, frozen Safe and secure Monitors in place - temperature probes used. Alarms if temp changes

Question 39

What is used to preserve a samples ?

Answer 39

Tissue removed from body no longerr blood supplyy and it will doe Fixation neccesary to prevent autolysis Samples routinely fixed in 10% formalin which also hardens the tissue.