Clinical Hematology Procedures Flashcards
Processing and testing the specimen
◦ When a preserved specimen stands for a time, the components settle into three distinct layers:
◦ Top layer: plasma
◦ Middle layer: buffy coat, a grayish-white cellular layer composed
of WBCs and platelets ◦ Bottom layer: RBCs
◦ Appearance of specimens
◦ Hemolysis
◦ Unsuitable hematologic specimens ◦ Homeostasis
Why we cancel the specimen?
when we run plate is low it get cloth
Layers of Normal Blood (using Microhematocrit tube)
Plasma.
Buffy coat (white blood cells and platelets).
Red blood cells.
Clay.
Hemoglobin measurement in the laboratory ◦ Cyanmethemoglobin method
Automated hemoglobinometry
◦ Point-of-care hemoglobin assay
◦ Principle: Hemoglobin determination: Hemocue method
Hematocrit (Packed Cell Volume)
◦ The hematocrit (Hct), or packed cell volume, is a macroscopic observation of volume of the packed RBCs in a sample of whole blood.
◦ The Hct is
the percentage of RBCs in a volume of whole blood.
◦ Hct is used
in evaluating and classifying the various types of anemias according to RBC indices.
Methods for Measurement
Complete Blood Cell count (CBC)
◦ Counting the various cells.
found in blood is a fundamental procedure in the hematology laboratory.
Complete Blood Cell count (CBC).
◦ In modern laboratories,
most cell counts are performed with automated equipment.
Complete Blood Cell count (CBC).
◦ Electronic counting devices
avoid human error, which is significant in manual cell counts, and are statistically more accurate because of sampling; these devices count many more cells than can be counted manually.
Blood cell counts – manual methodology Diluents used
White cell counts
Counting red and white blood cells
Clinical significance of cell counts Red blood cell counts
White blood cell counts
Platelet counts Specimens
Methods used to count platelets Clinical signifi
Automated hematology
instrument technology ◦ Principles of cell counting
Hemoglobin measurement
Automated cell counting methods ◦ Electrical impedance principle
◦ Optical detection principle
Histograms
Histograms
◦ Erythrocyte histogram
◦ Red cell distribution width
Examples of automated hematology technology
Automated leukocyte differentiation
◦ Platelet histograms
◦ Mean platelet volume calculation
◦ Platelet distribution width
◦ New automation technology
◦ Quality control
Reticulocyte counts (using new methylene blue supra-vital stain).
◦ Reticulocytes are red blood cells that have lost their nuclei but not all of their
cytoplasmic RNA.
Normal erythropoiesis and reticulocytes
◦ High reticulocyte count, reticulocytosis, is a clinical indication that the body is attempting to meet an increased need for RBCs.
◦ Clinical uses for reticulocyte counts ◦ Follow therapy for anemia
◦ Reference values
◦ Adults: 0.5% to 1.5% of circulating red blood cells ◦ Newborn: 2.5% to 6.0%
Erythrocyte sedimentation rate ◦ Rate depends on the following:
- Number and size of erythrocyte particles
- Plasma factors
- Certain technical and mechanical factors
The most important factor determining the rate of fall of the RBCs
(Erythrocyte sedimentation rate ◦ Rate depends on the following):
is the size of the falling particle. The size of the falling particles depends on the formation of RBC rouleaux.
◦ Results reported
(Erythrocyte sedimentation rate ◦ Rate depends on the following:)
in mm/hour
Clinical significance:
(Erythrocyte sedimentation rate ◦ Rate depends on the following:)
indicator of inflammation
Red Blood Cell Indices
Mean corpuscular volume (MCV)
the average volume of RBCs in femtoliters, as calculated in this equation:
Hct × 10
MCV (fL) = ————————————
RBC
where MCV is mean corpuscular volume, fL is femtoliters, Hct is hematocrit,
and RBC is red blood cell count. ◦ Reference range is 80 to 96 fL
Mean corpuscular hemoglobin (MCH) is
the content (weight) of hemoglobin in the average RBC, as calculated in this equation:
Hb × 10
MCH (pg) = ———————
RBC
where MCH is mean corpuscular hemoglobin, pg is picograms, and Hb is hemoglobin.
◦ Reference range is 27 to 33 pg.
Mean corpuscular hemoglobin concentration (MCHC) is
the average Hb concentration in a given volume of packed RBCs, as calculated with the equation:
MCH
MCHC (g/dL) = ————— × 100
MCV
where MCHC is mean corpuscular hemoglobin concentration, g is grams, and dL is deciliters.
Reference range is 33 to 36 g/dL
Red cell distribution width
◦ Red cell distribution width (RDW) is a measurement of the degree of anisocytosis present, or the degree of variability in RBC size, in a blood specimen, as shown in this calculation:
Standard deviation (SD) of MCV
RDW (%) = ——————————————— × 100 Mean MCV
Reference range is 11% to 15%.
in a blood specimen, as shown in this calculation:
Standard deviation (SD) of MCV
RDW (%) = ——————————————— × 100 Mean MCV
Reference range is 11% to 15%.
Microscopic Examination of the Peripheral Blood Film
Lymphocyte alterations
Variant lymphocytes (reactive or atypical lymphocytes)
Associated with viral infections Amount of cytoplasm increases
Nuclear changes generally include a sharper separation of chromatin and parachromatin.
Smudge or basket cells
Smudge cells are damaged white blood cells.
Lymphocyte alterations
Variant lymphocytes (reactive or atypical lymphocytes)
Associated with viral infections Amount of cytoplasm increases
Nuclear changes generally include a sharper separation of chromatin and parachromatin.
Smudge or basket cells
Smudge cells are damaged white blood cells.
Granulocyte alterations
Toxic changes and granulocyte alterations Dőhle bodies
Round or oval, small, clear, light-blue staining areas found in the neutrophil cytoplasm
Round or oval, small, clear, light-blue staining areas found in the neutrophil cytoplasm
Toxic granulation
Deeply staining basophilic or blue-black larger-than-normal granules found in the cytoplasm of neutrophils, bands, and metamyelocytes
Toxic vacuolization
Vacuoles in the cytoplasm of neutrophils and bands
Leukocytosis
is a white blood cell (WBC) count above normal.
Leukopenia is
a WBC count below normal.
Quantitative changes in any of the cell types are described by the
following terms:
Neutrophilia (increase) or neutropenia (decrease) Eosinophilia
Basophilia
Lymphocytosis or lymphopenia
Monocytosis
Hypochromic-microcytic anemias
Can be the most common types encountered
If iron deficiency-related, can result from
Decreased iron intake
Increased iron loss
An error of iron metabolism
Increased iron requirements in infancy, pregnancy, and lactation
Can also result from disorders in globin synthesis, porphyrin synthesis, and heme synthesis.
Types of anemias
Macrocytic anemias
Primarily represented by
megaloblastic anemias resulting from vitamin B12 or folic acid deficiency, or both.
The deficiency may be nutritional or may result from a malabsorption syndrome.
The deficiency
may be nutritional or may result from a malabsorption syndrome.
.
Megaloblastic changes are characterized by
by larger cells having a more open chromatin pattern in the nucleus and by the presence of larger, hypersegmented mature neutrophils in the peripheral blood.
Types of anemias Normochromic-normocytic anemia
Characterized by
normal-appearing RBCs on the peripheral blood film and RBC indices within the reference range
The cells produced by
the marrow are normal, but the number of cells in circulation is reduced for a variety of reasons, including acute blood loss.
Clinical significance of erythrocyte alterations
Clinically, alterations in erythrocyte morphology are
associated with many diseases and especially with anemia.
Anemia is
not a specific, single disease
Anemia is
a condition in which there is a decrease in the oxygen-carrying capacity of the blood that results in decreased oxygenation of the tissues and organs.
It has many causes, and the type of anemia and its underlying cause
must be determined before treatment can be effectively undertaken.
Perform the differential count of white cells.
The differential count consists of identifying and counting a minimum of 100 WBCs.
In cases of leukopenia,
only 50 cells need to be counted; then the differential percentages will need to be calculated.
Examine the leukocytes for morphologic alterations.
All WBCs in the circulating blood should be mature.
Persons with limited training in hematology should not attempt to identify abnormal WBCs.
Platelet estimation
Estimate the platelet count.
Normally, 6 to 20 platelets per.
oil-immersion field represents a normal platelet count of 150 to 450 × 109 per liter.
Report the platelet count as adequate
if 6 to 20 are seen per oil-immersion field.
Report the platelet count as decreased
.
if fewer than 6 are seen per oil-immersion field.
Report the platelet count as increased if more than 20 are seen per oil-immersion field.
Evaluate platelets for morphologic changes
if more than 20 are seen per oil-immersion field.
Microscopic examination of the blood film
◦ Accurate examination of the blood film depends on proper use of the microscope.
◦ Estimate of the RBC and WBC counts
◦ Scanning the blood film for abnormal cells and clumps of platelets
◦ High-dry objective is not suitable for examination of blood films.
◦ Oil-immersionobjective
◦ Low-powerobjectiveexamination
◦ Evaluation of the overall quality of the blood film smear preparation and staining
Estimate of the RBC and WBC counts
◦ Scanning the blood film for abnormal cells and clumps of platelets
◦ High-dry objective is not suitable for examination of blood films.
◦ Oil-immersionobjective
◦ Examination of the erythrocytes for alterations and variations in morphology
◦ Estimation of platelet count and evaluation of morphologic changes
◦ Differential count of the leukocytes
◦ Examination of the leukocytes for morphologic alteratio
Erythrocyte alterations
● Characteristics to note:
. Variations in color or staining reaction
2. Variations in size (anisocytosis)
3. Variations in shape (poikilocytosis)
4. Variations in structure and inclusions
5. Artifacts and abnormal distribution patterns
6. Presence of nucleated red cells
Sources of blood for the blood film
Fresh blood from a finger or heel puncture can be used for morphologic examination of the white and red cells.
◦ Only the drop of blood should touch the slide.
◦ If blood is collected in EDTA for morphologic studies, the film should be prepared as soon as possible, certainly within 2 hours.
Variations in color or staining
reaction Normochromic erythrocytes
Central pallor
Hypochromic erythrocytes
Variation in staining color
(pinkish blue) is called
polychromatophilia.
Polychromasia refers to RBCs that show a faint
blue or blue- orange color with Wright stain.
