Lab Investigation of the FBC Flashcards
Where are blood cells produced?
Bone Marrow
Long bones
Where do blood cells mature?
Maturation occurs in BM
Mature cells within peripheral blood
Outline the investigations of a full blood count (RBC results)
Hb: concentration of Haemoglobin Hct: Percentage of blood volume as RBC MCV: Average size of RBC MCH: Average haemoglobin content of RBC RDW: Range of deviation around RBC size Reticulocyte count Blood film
Describe the wbc results of a FBC
WHITE BLOOD CELL RESULTS
- Total WBC and differential
- Neutrophils, lymphocytes, monocytes,
- Basophils, eosinophils
What info do we obtain on platelets from a FBC?
Platelet count and size
What is the use of a blood film?
Blood films can confirm numbers of cells and their morphology – are the cells ‘normal’
Are there cells present that shouldn’t be?
Outline all the info we can obtain on RBCs from a blood film
Size - big / small (anisocytosis)
Colour - Hb count
Shape - round, TDP, irregular, elliptocytes, poikilocytosis
Polychromasia
Inclusions
Outline the info a blood film tells us about WBCs
Numbers - too many / few
Normal morphology - dysplastic features
Immature cells - myelocytes, precursors
Abnormal Cells - blasts, atypical lymphoid cells
Inclusions
What does a purple blood test tube indicate?
Purple lid - contains EDTA to stop blood clotting, FBC taken
What is the meaning of a yellow blood test tube lid?
Rust (yellow) lid - biochemistry samples; contain clotted gel at the bottom (tests for renal function etc.)
Describe what is meant by a turquoise blood test tube lid
Turquoise lid - citrate sample acts as an anticoagulant; threshold line on the tube to ensure correct amount of blood sampled
What does a pink blood test tube lid indicate?
Pink - EDTA used for transfusion and crossmatch (have to be handwritten)
What is the consequence of storing blood sample in the wrong tube?
If blood is put in the wrong tube, it can’t be used due to contamination risk
How are patient blood samples in test tubes identified?
Each sample gets a lab no. and barcode to identify
We process >1600 FBC samples/ day
What happens to a blood test sample once in a lab?
The sample is analysed and plotted based on light refraction and size
How are abnormal cells identified from the blood sample?
The machine changes these plots into quantitative numbers and alerts us to any abnormal cell presence
How can we identify a normal WBC distribution?
by size and staining can see where all the different types of cells sit normally on a plot
How are blood films prepared?
Blood films are prepared and stained using a staining machine and then analysed under a microscope
Diagnose a 65 y/o lady with the following sings and symptoms:
- tired
- shortness of breath on exertion
- ankle swelling
High neutrophil count
Low MCV
V. Low Hb
(IDA) Iron deficiency anaemia
Describe the blood film of IDA
Area of central pallor in most cells is much larger compared to normal cells
Decreased cell number
Elliptocytes seen in iron deficiency (really skinny elliptocytes known as ‘pencil’ cells)
Diagnose the following 50 y/o male patient:
History: gastrectomy due to cancer 20 yrs ago
Hb: v low (4.6)
MCV: very large 140 (normal range <95)
Macrocytic megaloblastic anaemia
Patient had gastrectomy so doesn’t contain parietal gastric cells; unable to produce IF and likely require B12 supplements → B12 deficiency
Describe the blood film of a macrocytic megaloblastic anaemia such as B12 deficiency
Oval shaped and debris present
Some very large RBCs; feature of macrocytic anaemias
What is the diagnosis of an 80+ male with:
Signs & symptoms: anaemia, jaundice and splenomegaly
Hb: low (5.7)
MCV: really large
WBCs: slightly higher
Acquired haemolytic anaemia due to development of antibodies destroying own RBCs
Splenomegaly due to absorption of faulty RBCs
Haemolysis - bone marrow still produces RBCs but they die too quickly (as reticulocytes) ⇒ polychromasia and spherocytosis
Jaundice due to intravascular breakdown of RBCs releasing bilirubin
Describe the blood film of an acquired haemolytic anaemia
Purple colour - polychromasia as reticulocytes contain RNA still
spherocytosis
Most RBCs in this blood film don’t have a central pallor and are v round - spherocytes
Describe the blood film of a SCA patient
Evident abnormal sickle cells present Target cells (central pallor with spot in the middle)
May be due to HbSS or HbSc
Polychromasia occurring due to early cell death
When are poikilocytes seen on a blood film?
Tear drop poikilocytes – seen in myelofibrosis (bone marrow scarring) or bone marrow infiltration with malignant disease
What are the potential diagnoses of a patient with plethora (red faced), splenomegaly, microcytic hypochromic anaemia with poikilocytes
Neutrophil leucocytosis -
V. closely packed, too many WBCs and RBCs due to infection and dehydration
Myeloproliferative process - genetic disorder where immune system produces excess WBC and RBCs
Diagnose the following patient with bruising, recent infection slow to clear
WBC: v.v. high (190 normal range (5-10))
Differentiation of WBCs is normal - something else is being counted as a WBC by machine
Platelet count: v low
Hb: low
Acute myeloblastic leukaemia - blast cells present
Machine counted blast cells as WBCs as they also contain nuclei and are of a similar size
This patient is unable to produce any normal healthy cells - leukaemia
What is the cause of this patient presenting with a painful foot, left sided discomfort ?
WBC: v.v. high (mostly flagging up as neutrophils)
Chronic granulocytic leukaemia – all stages of cell maturation represented
Describe the blood film of a patient with Chronic granulocytic leukaemia
Neutrophils with granulation present alongside myelocytes and promyelocytes (all stages of maturation occurring) - CM
What is the unusual diagnosis of this young man returning from kenya with a fever
Hb: normal
Platelet count: v.v.low
Malarial parasitization of red cells stained for
Visualized using blood film as not picked up by analyser
What test is carried out for malaria confirmation?
Malarial Antigen Test
Carried out to confirm diagnosis
