S3 L2 - Blood films

Question 1

when is a blood film carried out

how should results be interpretted

what values does the normal range include

One important thing to remember when interpretting

Answer 1

Samples with significant results outside of the normal range, significant change within the normal and abnormal (either immature or unable to identify) cells highlighted by the analyser are identified

Results should be interpretted in the clinical context of the patient and in relation to previous blood results

what values does the normal range include: 95% of people
(MAY BE NORMAL FOR THAT PERSON TO BE OUT OF THE NORMAL RANGE

One important thing to remember when interpretting: Just because a result is normal, doesn’t mean it is ‘healthy’ for that person, may still be high or low for this person (which is why looking back at previous blood work is helpful)

Question 2

dimorphisms

Answer 2

two distinct populations of red cells

Question 3

eliptocytosis

Answer 3

elliptical RBC

Question 4

normocytic

macrocytic

microcytic

Answer 4

normal size

abnormally large

abnormally small

Question 5

normochromic

hyperchromic

Answer 5

normal colour

densely packed Hb in the cell- appears darker than normal RBC

Question 6

hypochromic

Answer 6

less Hb in the cell- appears ligher and paler than ccells

Question 7

anisocytosis

Answer 7

variable sizes of RBC that is noticeably more than usual

Question 8

poikilocytosis

Answer 8

Variation in shape of RBC

Question 9

spherocytosis

Answer 9

RBC have a spehrical shape rather than a typical biconcave disck

Question 10

irregularly contracted cells

Answer 10

these are small dense RBC whose shape is not as regular as spherocytes, and have irregularly distributed condensed haemoglobin

Question 11

sickle cells

Answer 11

RBC are crescent (sickle) shaped

Question 12

tsarget cells (codocytes)

Answer 12

Hb is cocnentrated at the centre and the periphery of the RBC

Question 13

stomacytes

Answer 13

RBC have a pale slit in their centre, giving them a coffee bean appearance- lost biconcave shape so resemble a bowl

Question 14

schistocytes

Answer 14

RBC are fragmented

Question 15

acanthocytes

Answer 15

RBC have an irregular cell memrbane with a small number of spikey protrusions

Question 16

echinocytes (crenated cell)

Answer 16

RBC have an irregular cell membrane with a large number of regular spurs

• like acanthocyte

Question 17

inclusions of erythrocytes

Answer 17

howell-jolly bodies

basophilic stippling

papenheimer bodies

heinz bodies

Question 18

howell-jolly bodes

Answer 18

DNA or nuclear fragments present in RBCs

Question 19

basophilic stipping

Answer 19

there are RNA inclusion in the RBC

Question 20

pappenheimer bodies

Answer 20

Iron inclusions in RBC (pearl stain)

Question 21

heinz bodies

Answer 21

there are clumps of denature Hb present in RBC

Question 22

Haemoglobin H inclusion ​

Answer 22

Gold ball cells; denatured haemoglobin H (brilliant cresyl blue stain)

Question 23

iron deficiency: FBC and red blood cell indices

Answer 23

• Decreased:
  
  • Hb
  • MCV
  • MCG
  • MCHC
• May occur in haemoglobinopathies
• Increased RDW (more indicative of iron deficiency than thalassaemia

Question 24

iron deficiency: reticulocyte count

Answer 24

low or normal

• reduced for the degree of anaemia

Question 25

iron deficiency: blood film

Answer 25

• Hypochromic
• Microcytic
• Pencil cells
• A few target cells

Question 26

vitamin B12 deficiency

Answer 26

• Oval macrocytic
• Basophilic stippling
• Hyper segmental neutrophil

Question 27

platelets are very

Answer 27

reactive cells

• If any clots in the sample the platelet count will be reduced
  
  • Try to citrate (green tube) sample to prevent platelet clumping

Question 28

Where can errors arise with blood taking:
- 4 main and explain

Answer 28

Specimen collection error:

• There could be the wrong blood in the tube (blood is not that of the patient identified on the label).
• The wrong bottle could be used for the test (different bottles are required for different samples as they contain specific agents for that test).
• There could be pooling of different samples (repeated venepuncture to get a full tube).
• Poor technique or heavy handling of the sample can trigger the clotting cascade in the blood and alter the values affecting accuracy.

Delivery of specimen to laboratory error:

• The specimen can be delayed, not delivered or lost. A FBC must be processed within two hours of sampling, otherwise it is unusable.
• The specimen can be delivered by the wrong method. Some samples need to be delivered at certain temperatures while others need to be hand delivered (as the sample can be damaged) rather than by pneumatic tube like most samples.

Specimen analysis and result reporting error:

• Specimen mix up can occur at the lab due to human error.
• Incorrect clinical details can be recorded due to poor handwriting being misread, or incorrect information being written down.
• The wrong test requested or performed.
• There is inherent test variability for the analysers as they are not 100% accurate all of the time.
• Technical errors can occur with the analysers.

Responsive action error:

• Sometimes nothing is done in response to an abnormal result.
• Reflex tests (extra tests required in response to the results of the FBC) are not carried out.
• The right result is applied to the wrong patient.