RBC morphology Flashcards
Morphology of normal mammalian erythrocytes
Varies among species
Canine- biconcave disc shape with a distinct area of central pallor
Feline- round with little or no central pallor
Avian, reptiles, amphibians, and fish all have nucleated RBCs
Camellidae family have elliptical RBCs
Procedure for reporting RBC morphology
Under high dry (40x) find an appropriate monolayer area to evaluate (where you would perform your differential count)
Look for agglutination, reuleaux, parasites or an abnormal sized monolayer
Under oil immersion examine the erythrocytes for variations in size, shape, colour and the presence of inclusions
Morphological characteristics Categorized according to
Cell arrangement
Cell size
Cell colour
Cell shae
The presence of structures on or in the erythrocyte
Erythrocyte arrangement on blood smears: Rouleaux is
Is when the red blood cells appear in linear stack(like stocked coins)
A normal finding in horse
Cats and pigs will normally have a slight rouleaux
It can be an artefact if the blood has been stored too long before the smear is made, or it was refrigerated before a blood film was made
May be seen with increased total protein levels in the blood
Must be reported
Exception: rouleaux is not reported in the horse and is only reported in cats if it is 3+
Accompanied by an increase in erythrocyte sedimentation rate
Agglutination is and looks like
Results in irregular, spherical clumps of cells
In early stages, it may appear as increased rouleaux with some cells appearing to be connected by long, thin extensions of the RBCs cytoplasm
As it progresses, the cells will take on a muddy brown colour and “melted together” appearance
Occurs due to a reaction between antibodies (usually) and the antigens present on the surface of the RBCs
To differentiate rouleaux formation from true agglutination the following test can be performed
Mix a small amount of blood at a ratio of 50;50 with warm (or room temp) isotonic saline
Make a smear and stain as usual
If the formation disappears, it is due to a high total protein concern of the plasma
If agglutination is still visible, there is antibody involvement
Normocytic means
Cells of a normal size
Macrocytic means
Larger then a normal size cell
Microcytic means
Smaller then normal cells
Ansicytosis means
Variation in size
Common in cattle and rates therefore not reported
Macrocytic erythrocytes look like
Large in diameter, generally twice the size as normal
Dogs: erythrocytes only need to be slightly larger than normal to be classified as macrocytes
The cells have an increased MCV
Microcytic erythrocytes looks like
Smaller in diameter than normal
Often accompanied by hypochromasia
MCV will be lower than normal
RBCs should be what colour
RBCs are said to be normochromic when there are no abnormalities in cell colour
MCH (mean corpuscular hemoglobin) in normal
MCHC( mean corpuscular hemoglobin concentration) is normal
Polychromasia means
refers to a cell being darker in colour than normal
How to stain in order to see colour
Wright’s stain: appear as macrocytic, blue tinged red cells
They are immature RBCs
Blue staining is due to the presence of organelles within the cells
Polychromasia is important why and usually accompanied by
AN EXTREMELY IMPORTANT ELEMENT OF A PATIENT’S BLOOD PROFILE
Usually accompanied by
An increased number of nucleated RNCs
Hypersegmented neutrophils
Howell Jolly bodies
What does polychromasia indicate
Horses will release macrocytic RBCs that are not polychromatic
An increase indicates regenerative anemia→ good prognosis
A lack of macrocytic cells indicates a non-regenerative anemia→ poor prognosis
Hypochromasia look like
Cells are more pale in colour than normal
Increased central pallor
Due to a decreased hemoglobin concentration within the cell
Macrocytic RBCs can appear to be hypochromic because of enlarged cell size
Hypochromasia is caused by
Due to a decreased hemoglobin concentration within the cell
Can be due to poor smear technique
-Have what looks like a punched out center
What can hypochromasia indicate
Micrystosis often accompanies hypochromasia
-Iron deficiency
Hyperchromasia is
Cells that are stained darker than normal
RBC have a fixed maximum so versaturation is not possible
Hyperchromasia is usually seen spherocytes or microcytic cells
Erythrocyte shape can indicate
When describing the RBC shape, be as specific as possible
Certain shapes indicate specific diseases
Your role as a tech for erythrocyte shapes
Identify if abnormal cells are present
Name the abnormal cells
Quantify the abnormal cells
Schistocytes look like and are a result of
These are RBC fragments
They are generally the result of shearing the cell from intravascular trauma
Echinocytes look like
Have short, evenly spaced, blunt to sharp surface projections that are uniform in size and shape
Often an artefact from drying the slide too slowly, being refrigerated, or put in a hypertonic solution
Can be due to pathological processes
Echinocytes are classified as and how to tell the difference
Echinocyte 1 (crenated cells)- very short projections
Echinocyte 3 (Burr cells)- very thin, tall, quill like projections
Projections are of equal length and are evenly spaced over the periphery of the cell
Acanthocytes look like
An irregularly, spiculated RBCs
Have a few unevenly distributed surface projections of variable size and diameter
Can be a normal finding in cattle
There is often underlying pathology if they are present in large numbers in small animals
Drepanocytes look like and indicate
Look like smushed RBCs
Also called sickle cells
Normal finding in deer and angora goats
Keratocytes look like
These are RBC containing 2 or more spicules (long projections tha outlook like horns or crescents)
May appear to contain a vacuole
May appear in small numbers on blood smears from healthy animals
Sphyrocytes look like
Darkly staining RBCs that don’t contain central pallor (appear to be hyperchromic)
Smaller than normal RBCs with normal MCV
Almost perfectly round
Usually only detectable in dogs
Seen with IMHA
Leptocytes look like and are caused by
A large cell membrane to volume ratio which causes the membrane to fold
The cell looks like it has two areas of central pallor
Usually due to improper filling of EDTA tubes (not enough blood)
Has several variations, depending on the reference
Considered an artefact of the areas of central pallor are all perpendicular to the feathered edge
Different types of leptocytes
They are often separated out and treated as separate cell types
Codocyte
Stomatocyte
Knizocytes
Codocytes are
Also known as target cells
Cells look like a bullseye or target
The cells have a dense, central area of hemoglobin that is separated from the peripheral hemoglobin by a clear zone
Up to 50% are normal in dogs - rarely seen on other species
Can be due to artefact or underlying disease process
Stomatocytes are
Contain an oval central pallor
Seen with hereditary stomatocytosis of Alaskan Malamutes
Clinical significance is unknown
Knizocytes look like
Has a dark bar of hemoglobin across the center of the cell
Elliptocytes /ovalocytes look like and are normal in
Normal in camelids
These are oval shaped red blood cells
Abnormal in other species
Eccentrocytes look like
Believed to be the precursor to the keratocyte
Loss of central pallor
Have 1 or 2 large clear zones outlined by a membrane
Often accompany heinz bodies
Can be an artifact
Dacrocytes look like
Cells are shaped like a tera drop
If all the tails of the dacrocytes are the same direction, they are likely an artefact
Ghost cells look like
These are cells that have been leached of their hemoglobin
Poikilocytes look like and is used when
This is a blanket term that means that the erythrocytes have an abnormal shape
It should only be used when none of the other descriptors apply
Structures on or in RBCs
Basophilic stippling
Howell-jolly bodies
Heinz bodies
Nucleated erythrocytes
Siderotic granules
Parasites
Basophilic stippling looks like
Looks like a blue dustin on the cell
Caused by residual RNA
Howell-jolly bodies look like
Nuclear remnants
These are small, round, dark- blue inclusions of variable size usually just off center
Not to be confused with stain sediment
Heinz bodies look like
Oxidative denaturation of the hemoglobin
1-5% in normal cats
Appear as small, eccentric ale structures within RBCs
They appear to stick out or protrude from the edge
In cats they are single and large
In dogs they are small and multiple
Nucleated erythrocytes look like
The red blood cell will be slightly larger than a mature cell and will contain a nucleus
Usually associated with an underlying pathology
How to Record nucleated RBCs
Count the number of nucleated RBCs (nRBC) seen while examining 100 WBCs for the differential count
Recorded as nRBCs/100 WBCs
Used to perform a corrected WbC count
Corrected white blood count
Corrected WBC count = (total WBC x 100)/ (100+ nRBCs)
Siderotic granules look like
Stainable iron granules within mitochondria and lysosomes (generally on the side of cells, lighter than Howell-Jolly bodies)
Extremely rare
Parasites can look like
Often seen with agglutination and spherocytes due to immune mediated anaemia
Blood parasites found in domestic animal species include
Dirofilaria immitis
Anaplasma
Babesia
Ehrlichia
Mycoplasma
What are the most common parasites by species
Dogs are most commonly affected with dirofilaria immitis or babesia canvas
Horses are most commonly affected with babesia caballi
The most common blood parasite of cats is mycoplasma haemofelis
Dirofilaria immitis (heartworm) looks like
The immature stage circulates in the bloodstream and can be drawn into a syringe with a blood sample
It will be a large worm on the slide and seen under low power
Mycoplasma haemofelis is
Cause feline hemotrop(h)ic mycoplasmosis (previously known as feline infectious anemia) due to lysis of the RBCs
How to tell the difference on a slide between Mycoplasma haemofelis and stain sediment
Can be difficult to differentiate from stain sediment of drying artefacts
Stain sediment will be seen between the RBCs in equal proportions as on top of the RBCs
Drying artefacts will be refractive and of varying shapes
The microscope is only slightly refractive and goes in and out of focus when doing the red blood cells
Mycoplasma haemofelis looks like
They appear as small, oval to slightly rod shaped structures along the cells periphery as single organisms or in chains or rings (tiny strings of pearls)
Agglutination is usually present as well
Transmitted through blood- outdoor cats are more susceptible, particularly males
Ectoparasites- most common
Blood transfusions, fights- less common
Possible from the queen to her kittens
It may take several blood samples taken over the course of days/weeks to find the organism
PCR test
Ehrlichia and anaplasma is in what animals
Various species of organisms affect cattle and dogs
Transmitted by arthropods or ticks
Significant name changes within this group of parasites has occurred in recent years
Ehrlichia and anaplasma looks like
Gram negative, rod shaped, spherical, coccoid, or ring shaped bodies within the RBCs
Must be differentiated from Howell-Jolly bodies
Blood smears made from the buffy coat may aid in diagnosis
Diagnosis is usually confirmed with an ELISA snap test (immunological test)
Has been found in Saskatoon in non-travelling dogs (previously only seen in US)
Babesia canis is infected by what
A protozoan infection
Transmitted by ticks
Babesia canis looks like
Produces severe hemolytic anemia
Usually appears as paired teardrop shaped organisms within the red blood cells
The organisms stain darker than the rest of the red blood cell
Babesia cabelli are very similar but are found in horses
Babesia spp. affect cattle, goats, sheep, and cats
Viral inclusions in blood cells look like
Distemper inclusions are rarely seen in dogs
When found, they appear as faint blue to magenta, round structures of variable size and number
Usually seen in polychromatophilic red blood cells
Can be seen in neutrophils as well
How many cells need to be examined to quantify abnormal morphology
Subjective Assessment–at least 200 cells should be examined (100x magnification in a non-anemic patient)
Quantifying rouleaux
1+ majority of cells are free, some chains of cells, maximum of 2-3 cells in a chain
2+ At least 1/2 of the cells are free, many chains of cells, usually <5 in a chain
3+ almost no free cells are present, most cells are in chains, >5 cells in a chain
Organization of a CBC
You should always perform tests in the same order
It makes it less likely to miss a test component
You can also separate tasks into categories to help minimize them from being missed
Categories include:
Direct measurements
Microscopic procedures
Calculations
Direct measurements are
PCV
RBC count
MCV
WBC count
Total protein
Platelet count
Mean platelet volume
Microscopic procedures are
Differential white blood cell count
WBC estimation
Toxic change
RBC morphology
Platelet morphology
Platelet estimation
Reticulocyte enumeration
Calculations for RBC
Absolute WBC count
RBC indices
MCV
MCHC
MCH
Hemoglobin concentration
Reporting RBC morphology results
To report this data, one should organize by cell line or cell fragment
Leukocytes
Erythrocytes
Platelets
Keep each cell lien information together and always in the same order
This will allow for a more efficient interpretation of results
