The elevated WBC flagged and reflex testing indicated that a manual differential should be performed.
The technologist performed the differential and noted several items:
• The WBC count of 35,000 did not correlate with the slide.
• 100 nRBCs were counted while completing the differential.
• The patient had anisocytosis, probably due to younger polychromatic cells.
• The patient had poikilocytosis including moderate target and moderate sickle cells present.
• The patient had the presence of RBC inclusions: Pappenheimer and Howell-Jolly bodies.
It was obvious to the technologist that this was a sickle cell patient in a crisis with an elevated RDW and the peripheral smear indicative of sickle cell crisis. The presence of 100 nRBCs counted in the differential is a significant finding. nRBCs were most likely being counted as white cells, falsely elevating the white cell count. The Coulter LH750 usually corrects for the presence of nRBCs when the nRBCs are in the low range, but an nRBC count of 100 is fairly high and the instrument calculation has not been reliable in the high range. The instrument reported out a white count of 35,000, but the technologist thought that this count did not agree with the peripheral smear. The technologist needed to manually correct the white count. In order to perform this function, the technologist referred to the raw data function available in the Coulter instrument, to find what the WBC count was prior to correction by the instrument. The number of the WBC was 49,800 and represents the raw number of white cells counted on the initial run of this sample. This number was used to correct for the nRBCs using the formula shown in Figure 8.4.
Uncorrected WBC X 100 49.8 X 100
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