Week 7

Question 1

List 2 types of point of care whole blood COAGULATION assays

Answer 1

Thromboelastography (TEG)
Rotational Thromboelastometry (ROTEM)

Question 2

List 2 whole blood PLATELET FUNCTION assays

Answer 2

Multiplate

TEG6s

Question 3

List the advantages of point of care coagulation tests

Answer 3

Fast turn-around
Whole blood (no need to centrifuge)
Real time visual display
Reduction in non-evidence-based transfusion

Question 4

List the disadvantages of point of care coagulation tests

Answer 4

Artificial conditions
Training and competency of non haematological staff
Rigorous quality assurance standards
More expensive

Question 5

Describe the principle of the ROTEM

Answer 5

There is a rotating axis, a formation of a clot leads to a change in the torque, computer develops a curve and numerical parameters.

Question 6

EXTEM = the combination of what

Answer 6

MCF (max clot firmness) = sum of fibrinogen + platelets + F XIII activity

Question 7

What is the principle of the TEG

Answer 7

Sample is vibrated with a multi tone frequency, movement of the meniscus is monitored

Question 8

What does ESR stand for?

Answer 8

Erythrocyte Sedimentation Rate

Question 9

ESR measures the rate of what?

Answer 9

Measures rate of fall of Red Blood Cells

Question 10

ESR is Influenced by _______charged plasma protein levels and ________ charged Erythrocytes

Answer 10

positive, negative - they repel eachother

Question 11

A High retic count =

Answer 11

high rate of release of RBC from marrow

Question 12

Reticulocyte is the last immature stage in

Answer 12

erythropoiesis

Question 13

Do babies have a higher retic count?

Answer 13

yes especially at birth

Question 14

What are reticulocytes? What are you seeing in on a blood film?

Answer 14

Remnants of cell production in cytoplasm

• RNA, organelles (mitochondria, ribosomes)

Question 15

Describe the principle behind Electrical impedance For WBCC, RBCC & Platelet counts.

Answer 15

Particles are drawn through a small aperture with a DC current, each particle = a count, displacement of volume = size

Question 16

Degree of light scatter is proportional to particle ______

Answer 16

size

Question 17

With the beckman coulter instrument what is measured directly and what is calculated/derived?

Answer 17

Directly: RBC, WBC, & Hb
Calc/Deriv: Hct, MCH, MCHC, RDW
MCV = average volume from size distribution data

Question 18

What are the advantages in automation in FBC

Answer 18

• Speed / throughput
• Reproducibility (precision)
• On-line to laboratory information system

Question 19

List some factors to consider when selecting

a haematology analyser

Answer 19

• Range of tests
• Time per analysis
• Automation
• Reagent supply
• Sample size and microsampling
• Accuracy, precision, and linearity
• Maintenance, calibration, and QC
• Results analysis and storage
• Footprint

Question 20

List 3 Pre-Analytical limitations and interferences that can occur

Answer 20

Collection - errors and artifacts
Age - deterioration
Transport - too hot, too cold

Question 21

List some Analytical limitations and interferences that can occur

Answer 21

• Very high cell counts (linearity)
• Lipaemia
• Nucleated red blood cells
• QC out of range
• Operator error (manual or automated)

Question 22

Reference range = interval within what percentage of population falls

Answer 22

95%

Question 23

List 2 Advantages of point of care testing units

Answer 23

• Rapid results

* Portability – ambulance, helicopter, operating theatre

Question 24

List some shortcomings of point of care testing units (4)

Answer 24

• Range of tests (usually limited)
• Operator variability
• Connectivity, capture of results
• Cost

Question 25

What are some factors that influence ESR results.

Answer 25

positively charged plasma proteins
negatively charged RBCs
Rouleaux would cause a raised ESR