At the end of this chapter, the reader should be able to do the following: 1. Estimate the hematocrit if given the hemoglobin using the rule of three and vice versa. 2. Estimate the hemoglobin if given the red blood cell count. 3. Calculate red blood cell indices (MCV, MCH, MCHC). 4. Correct the WBC count for the presence of nucleated red blood cells. 5. Calculate white blood cell, red blood cell, and platelet counts performed on a hemacytometer for blood and body fluids. 6. Calculate the sperm concentration per milliliter. 7. Calculate the sperm count per ejaculation. 8. Calculate the number of reticulocytes by both the slide and Miller disk method. 9. Correct the reticulocyte count for anemia using the reticulocyte index. 10. Correct the reticulocyte count when increased reticulocyte production is present. The majority of RBC, WBC, and platelet counts are performed by automated hematology analyzers. Occasionally, the count may be too low for the instrument to count the cells accurately. WBCs in body fluids are often counted manually. In these instances, cells are counted with the aid of a microscope using a counting chamber called a hemacytometer (Figure 9–1). The most common hemacytometer used in clinical hematology is the Neubauer hemacytometer. This hemacytometer consists of two identical counting chambers. Each chamber contains an etched grid constructed to have a total surface area of 9 mm2. The chambers are identical, so that a sample can be counted in duplicate using the same hemacytometer. The count from each chamber should be within 10% of each other to ensure an accurate count. A dilution of whole blood is used and a small amount of diluted sample is allowed to flow between the coverslip and hemacytometer chamber. The distance between the coverslip and the surface of the hemacytometer is 0.1 mm. Figure 9–1 is a schematic of a Neubauer hemacytometer grid in which each of the large squares is numbered 1 to 9. WBCs are counted in the four corner squares (squares Nos. 1, 3, 7, and 9), whereas platelets and RBCs are counted in the central square (square No. 5). Each large square is 1-mm2 in area. The large squares are further divided into 16 smaller squares to facilitate ease of counting the WBCs. The center square is divided into 25 small squares. Each of the 25 small squares is further divided into 16 smaller squares for RBC and platelet counting. The small square A is shown enlarged in Figure 9–2. The mathematical formula to calculate the number of cells per cubic millimeter is as follows: Area counted = number of large squares counted Depth factor = reciprocal of depth [1/(1/10)] = 10 Dilution factor = reciprocal of dilution The WBC count reference range in adults is 4–11 (109/L) The mathematical formula to calculate the factor is as follows: Factor = 1/area × depth factor × dilution factor Area counted = number of large squares counted Depth factor = reciprocal of depth [1/(1/10)] = 10 Dilution factor = reciprocal of dilution = [1/(1/20)] = 20 Multiply the amount of cells counted by the factor of 50: A manual WBC count was performed by a medical laboratory technician/clinical laboratory technician student in a student laboratory experiment. The four large squares of one side of a hemacytometer were used, and the dilution used was Since the four large squares were used, and the dilution was A manual WBC count was performed by a medical laboratory technologist/clinical laboratory scientist student in a student laboratory experiment. The four large squares of one side of a hemacytometer were used, and the dilution was Since the four large squares were used, and the dilution was As there are so many more RBCs than WBCs, the cells are diluted The formula to calculate the factor for RBC counts is as follows: Factor = 1/area × depth factor × dilution factor Area counted = area of small squares counted = 0.2 mm2 Depth factor = reciprocal of depth [1/(1/10)] = 10 Dilution factor = reciprocal of dilution = [1/(1/200)] = 200 The mathematical formula for the factor for platelets is as follows: Factor = 1/area × depth factor × dilution factor Area counted = area of small squares counted Depth factor = reciprocal of depth [1/(1/10)] = 10 Dilution factor = reciprocal of dilution = [1/(1/100)] = 100 A platelet count was performed using a The factor for platelets is 1000. Therefore, the platelet count is 1000 × 85 or 85,000/mm3. A platelet count was performed using a Samples for these fluids are usually collected in a heparinized or an EDTA tube. Table 9–1 contains the body fluid normal results. TABLE 9–1
Hematology Laboratory
RED BLOOD CELL INDICES
CELL COUNTING BY THE HEMACYTOMETER METHOD
White Blood Cell Count
Example 9–7
Example 9–8
Red Blood Cell Count
Platelet Count
Example 9–10
BODY FLUIDS
Cell Counts for Synovial, Pleural, Pericardial, and Peritoneal Fluid
CSF
Serous (Pleural, Pericardial, Peritoneal)
Synovial
Adult
Neonate
Appearance
Clear and colorless
Clear and colorless
Pale yellow and clear
Pale yellow and clear
RBC
0 to 1/mm3
0 to 3/mm3
0 to 1/mm3
0 to 1/mm3
WBC
0 to 5/mm3
0 to 30/mm3
0 to 200/mm3
0 to 200/mm3
Neutrophils (includes bands)
2% to 6%
0% to 8%
<25%
<25%
Lymphs
40% to 80%
5% to 35%
<25%
<25%
Monocytes
5% to 45%
50% to 90%
Included with others
Included with others
Others
Rare
Rare
Monocytes and macrophages 65% to 75%
Monocytes and macrophages 65% to 75% Stay updated, free articles. Join our Telegram channel
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