NOTE: When performing the white cell count, you may observe abnormal white cells such as distorted lymphocytes, smudge cells, and disintegrated cells. Distorted lymphocytes, which appear squashed or distorted, are caused by excessive pressure on the cell during the process of making the smear. Distorted cells should be recorded as normal lymphocytes. Smudge cells are white cells that have ruptured and only the nucleus remains. Afew smudge cells may be found in a normal blood smear. Smudge cells should not be added to the count or recorded. Disintegrated cells are ruptured cells, but the nucleus and cytoplasm still remain. Disintegrated cells should not be counted as one of the 100 cells, but should be recorded on the report as “disintegrated cells.” 8. Once the differential count is completed, proceed to step 4, reporting the count. NOTE: If it is desirable to save a smear for reexamination, remove the immersion oil by placing a piece of lens tissue over the slide and moistening the tissue with xylene. Draw the damp tissue across the slide, and dry the smear with another piece of lens paper. REPORTING THE COUNT.—When you have calculated the differential count, the report is given according to either the Schilling classification or filament and nonfilament classification methods. We will be covering the Schilling classification, since it is the simplest and most popular method. The Schilling Classification.—The Schilling classification was established when Victor Schilling, a German hematologist, noticed that in many diseases there is an increase in the percentage of immature neutrophils. The blood chart he developed reported the percentages of the different neutrophilic cell types and (in part) was arranged in the following manner: Normal % Myelocytes Meta- myelocytes Band Cells Segmented Cells 0 0 2 to 6 55 to 75 Note that the immature cells are on the left side of the chart. If percentages of immature cell increased, Schilling referred it as a “shift to the left.” When the shift to the left was accompanied by a low white cell count, Schilling called it a “degenerative shift to the left.” A degenerative shift to the left is seen in such diseases as typhoid fever. This shift is caused by a depression of the cell factories in the bone marrow. When the shift to the left is accompanied by a high white cell count, it is called a “regenerative shift to the left.” A regenerative shift to the left is seen in such diseases as pneumonia. This shift is caused by a stimulus of the cell factories in the bone marrow. A “shift to the right” implies an increase in hypersegmented neutrophils. It may be seen in pernicious anemia, an anemia caused by the malabsorption of vitamin B₁₂. The Schilling classification for an adult differen- tial white cell count is provided below in table 7-2. NOTE: Normal values for differential counts vary with the age of the patient. For example, children’s blood normally contains 0% to 2% basophils, 0% to 5% eosinophils, 25% to 75% neutrophils, 30% to 70% lymphocytes, and 0% to 8% monocytes. Normal values may also be adjusted by hospitals that have evaluated the normal differential value for their local population. General Interpretations of Leukocyte Changes.—Together, the total white cell count and differential count aid physicians in interpreting the severity of infections. Some general interpretations of leukocyte changes are as follows:  Leukocytosis with an increase in the percentage of neutrophils indicates a severe infection with a 7-24 Cell Normal % Neutrophilic myelocytes 0 Neutrophilic metamyelocytes 0 Neutrophilic band cells 2 to 6 Neutrophilic segmented cells 55 to 75 Lymphocytes 20 to 35 Monocytes 2 to 6 Eosinophilic segmented cells 1 to 3 Basophilic segmented cells 0 to 1 Table 7-2.—Schilling Classification of the Differential White Cell Count