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.
