Laboratory Medicine Department
Saudi German Hospital-Jeddah

 Discuss the procedure for proper red blood cell examination
 Discuss aspects of red cell morphology related to size
 Discuss aspects of red cell morphology related to color
 Discuss different types of poikilocytosis

 Red cell morphology can be defined as the appearance of the erythrocytes on a Giemsa stained smear.
 Careful examination of the red cells for the purpose of identifying abnormalities is part of the differential procedure.

 differentiating normal morphology from abnormal and artificial morphology.
 provide valuable diagnostic information to the physician,
 provide a quality control mechanism to verify red cell indices values as determined by automated or manual methods.

 Assess RBC morphology by examining the smear in the feathered (thinner) edge where the
RBC are randomly distributed and, for the most part, lie singly, with occasional doublets.
 This area is referred to as the
"critical area."

 If the area is too thin, the red cells will appear flat and somewhat square (cobblestone effect) with no central pallor.
 If the area examined is too thick, the cells will be too close together to evaluate the morphology of individual cells.

 To begin the red cell morphology examination, use the low power
(10X) objective to locate the
"critical area."
 The oil immersion objective (100X) is used for the actual evaluation.

 Round, elastic, nonnucleated, bi-concave discs
 Many RBCs have an area of central pallor which covers about one-third of the cell.
 The pallor occurs as a result of the discshaped cells being spread on the slide.

 Average diameter of 7.2 microns with a range of 6-
9 microns, almost the same size as the nucleus of a small lymphocyte,

 A view of the
"critical area" using the low power (10X) objective is shown here.

 Once the correct area has been located on low power, switch to oil immersion
 Notice the red cells are lying singly with occasional doublets.

 The area shown in this field is too thin for accurate red cell morphology evaluation.
 The cells have large spaces between them, show no central pallor and many are somewhat square, showing a
"cobblestone effect."

 These cells are in an area which is too thick, and should not be used for red cell morphology assessment.
 Some of the cells appear to be stacked like coins because of the large number of cells present in this section of the slide.

 The morphology seen in the too thin and too thick areas of the smear is referred to as artificial
morphology.

 Red blood cells can vary in size from smaller than normal, microcytes, to larger than normal, macrocytes.
 When red cells of normal size, microcytes and macrocytes are present in the same field, the term anisocytosis is used.

 Size of normal
RBC is almost the size of the nucleus of the lymphocyte.

 Smaller than a nucleus of the lymphocyte, central pallor is greater than 1/3 of the cell

 microcytes have a diameter of less than 7 microns and an MCV of less than 80 cubic microns.
 Two types of microcytes can be seen, those with increased central pallor and those with normal central pallor.

 diameter of 9-14 microns (1.5 - 2 times larger than normal red cells)
 MCV is 100 cubic microns or more.

 Megalocytes are the result of decreased DNA synthesis, frequently due to vitamin B12 and/or folic acid deficiencies.
 Decreased DNA synthesis causes the nucleus in the developing red cells to mature at a slower than normal rate.
 Since hemoglobin production is not affected, the mature red cell is larger than normal

 appears larger than the lymphocyte but in contrast to megalocytes has an area of central pallor.
 size is the result of exaggerated flattening and thus the presence of the central pallor.
 in patients with cirrhosis of the liver, obstructive jaundice, post splenectomy.

 two types of macrocytes:-
• True macrocytes (megalocytes).
Increased MCV, MCH
• Pseudomacrocytes. Normal MCV,
MCH

 Increased variation in size of the red cell population present on a blood smear.
 Normal, small and large cells can be seen in one field.
 Normal MCV, high RDW
 As the severity of the anemia increases, the amount of significant anisocytosis present also increases.

• RDW is an expression of the homogeneity of the RBC population size.
• A large RDW says there's a wide variation in the RBC diameters within the test pool.
• It doesn't say the cells are large or small, rather that the population is not homogenous.
• Younger cells are larger (reticulocytes).
• Older, and generally beat up, RBCs are smaller.

 Erythrocytes, when spread on a glass slide, show varying degrees of central pallor
 This central pallor is related to the hemoglobin concentration present in the red cells.

 the central area (1/3 of the cell) is white, while buff-colored hemoglobin is visible in the outer 2/3 of the cell.
 The MCHC (32-36 gm/dl) is the index value which is used to verify the presence of adequate hemoglobin concentration in the cells visible on the peripheral smear.

 A decreased amount of hemoglobin is referred to as hypochromasia or hypochromia.
 MCHC values of 30% or less reflect this condition.
 Hyperchromasia and hyperchromia, refer to a hypothetical situation rather than an actual occurrence.

 Cells located in the "too thin" portion of the smear often appear to be "hyperchromic".
 Megalocytes (macrocytes) are normochromic.

 Variations in shape.

 Uniform terminology based on
Greek roots

 1+ = 2 – 4 /OIF
 2+ = 5 - 7
 3+ = 8 - 10
 4+ = >10
 The terms few, moderate, many, and marked may be substituted for the 1+ - 4+ grading system.

• 3-12 thorn-like projections irregularly spaced around the cell.
• Smaller than normal and have little or no central pallor.
• Acanthocytes have an excess of cholesterol
• Large numbers of these cells on a smear can be of diagnostic significance.

• Abetalipoproteinemia
• Hereditary acanthocytosis,50 –
100% of blood cells.
• Alcoholic cirrhosis
• lipid disorders
• splenectomy

• Target cells are thinwalled cells showing a darkly-stained centre area of hemoglobin which has been separated from the peripheral ring of hemoglobin.

 Codocytes appear in conditions which cause the surface of the red cell to increase disproportionately to its volume.
 This may result from a decrease in hemoglobin, as in iron deficiency anemia, or an increase in cell membrane.

 Thalassemias, Hb C disease, post splenectomy, obstructive jaundice.

• Dacryocytes are pearshaped or teardrop shaped cells.
• myelofibrosis/myeloid metaplasia,

• Drepanocytes or sickle cells are formed as a result of the presence of hemoglobin S in the red cell.
• As the red cell ages, it becomes less flexible or deformable and becomes rigid as it passes through the low oxygen tension atmosphere of the small capillaries in the body.
• In the absence of oxygen, hemoglobin S polymerizes into rods, causing the sickle cell shape.
• Sickle cells can be somewhat pointed at the ends,

• Most sickled cells can revert back to the discoid shape when oxygenated.
• About 10% of sickled cells are unable to revert back to their original shape after repeated sickling episodes.

• Echinocytes are reversible,
• The projections are rounded and evenly spaced around the cell.
• Acanthocytes have irregularly spaced thorn-like projections.

• Uremia,
• Following heparin injection,
• Pyruvate kinase deficiency.
• Artificial

• Elliptocytes can vary in appearance from slightly oval to thin pencil-shaped forms.
Less than 1% of red cells in normal blood are oval.

• Hereditary
Elliptocytosis
• Thalassemia, megaloblastic anemia, iron deficiency.

Elliptocytosis

• A streak of hemoglobin through the centre of the cell.
• In some hemolytic anemia cases

 Keratocytes are cells which have been damaged due to contact with fibrin strands.

 intravascular coagulation
 microangiopathic hemolytic anemia
 glomerulonephritis
 rejection of renal transplants.

 Schistocytes are red cell fragments which are formed when fibrin strands come in contact with circulating red cells. The strands cut a small piece from the original cell.

• cells which have a decreased surface-tovolume ratio.
• cell is thicker in diameter than normal red cells
• they appear to be round, darkly-stained cells without central pallor.

Spherocytes

 Hereditary spherocytosis
 Immune hemolytic anemia
 Severe burns
 In-vitro prolonged storage of blood

• cup-shaped erythrocytes which have an elongated or slit-like central pallor.
• hereditary stomatocytosis, neoplastic disorders, liver disease and Rh null disease, in-vitro change in pH

 Forms of poikilocytosis describing a group of cells.
 True and false

 most of the red cells, in the proper viewing area, are stacked together like coins.
 Four or more cells make up each formation, leaving much of the field empty of cells (increased white space).
 Rouleaux is clinically significant when increased globulins are present, as in multiple myeloma.

• Cells clumping together rather than stacked like coins.
• Autoagglutination is caused by the presence of antibody in the plasma.

 Match the following terms with their synonyms.
 Target cell
 Helmet cell
 Ovalocyte cell

 Match the following terms with synonyms:
 Crenated cell
 Tear drop cell
 Sickle cell

 Match the forms of poikilocytosis with the physiological/environmental condition associated with their formation :
 Damaged by fibrin strands
 Absence of abetalipoprotein
 Hemoglobin S

 A general term describing variation in size:
 anisocytosis
 macrocytosis
 microcytosis
 poikilocytosis

 helmet cell
 echinocyte
 crenated cell

 hypochromic
 hyperchromic
 normochromic
 polychromatophilic

 macrocytic/normochromic
 microcytic/hypochromic
 normocytic/normochromic
 normocytic/hypochromic