Required section · Section 4 of 6

Work the flagged case to a defensible result

For this flagged specimen, perform a 200-cell battlement count in the monolayer to inspect lymphocyte morphology. The count is 132 segmented neutrophils, 38 small lymphocytes, 10 reactive-appearing lymphocytes, 14 monocytes, 4 eosinophils, and 2 basophils. Convert each category to a percentage by dividing by 200 and multiplying by 100.

The manual lymphocyte total is 48 of 200, or 24%. It consists of 19% small lymphocytes plus 5% reactive-appearing lymphocytes, matching the analyzer lymphocyte percentage of 24%. The analyzer may use impedance, an electrical-resistance pulse method that estimates cell volume as cells pass an aperture, along with light scatter or fluorescence; it does not reliably name reactive morphology.

Calculate an estimated absolute reactive lymphocyte count from the total WBC: 9.8 × 10^9/L × 0.05 = 0.49 × 10^9/L. This is calculated rather than directly measured. The manual and automated neutrophil percentages both equal 66%, and the other categories agree in this case.

Bar chart showing identical automated and manual totals: neutrophils 66%, lymphocytes 24%, monocytes 7%, eosinophils 2%, and basophils 1%. The manual lymphocyte bar is partitioned into 19% small lymphocytes and 5% reactive-appearing lymphocytes. — Figure 1Automated and manual differential percentages in the flagged case; reactive-appearing lymphocytes are 5% within the 24% lymphocyte total.

Worksheet showing WBC 9.8 times ten to the ninth per liter multiplied by reactive lymphocytes 5 percent or 0.05 equals estimated absolute count 0.49 times ten to the ninth per liter. — Figure 2Worked estimate of the reactive-appearing lymphocyte absolute count.

Adult outpatient EDTA specimen, collected 08:10 and reported 08:52. Case reference interval for WBC: 4.0 to 11.0 × 10^9/L.
Category	Automated result	Manual count of 200	Manual percentage
WBC	9.8 × 10^9/L	Not applicable	Not applicable
Neutrophils	66% / 6.47 × 10^9/L	132	66%
Lymphocytes total	24% / 2.35 × 10^9/L	48	24%
Normal-appearing lymphocytes	Included above	38	19%
Reactive-appearing lymphocytes	Flagged for review	10	5%
Monocytes	7% / 0.69 × 10^9/L	14	7%
Eosinophils	2% / 0.20 × 10^9/L	4	2%
Basophils	1% / 0.10 × 10^9/L	2	1%

Knowledge checks

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Knowledge check 1

What is the manual total lymphocyte percentage in the 200-cell case?

Choose one option.

24%, from 38 normal-appearing plus 10 reactive-appearing lymphocytes out of 200.

19%, because reactive-appearing cells are excluded from lymphocytes.

5%, because only the flagged subset is counted.

Knowledge check 2

Using WBC 9.8 × 10^9/L and reactive-appearing lymphocytes 5%, what is the calculated estimate?

Choose one option.

0.49 × 10^9/L.

1.96 × 10^9/L.

4.9 × 10^9/L.

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