What Do I Do When the Hematology Analyzer Fails to Report a Differential Count?
An 82-year-old man came through the emergency department with altered mental status. His initial WBC through the hematology analyzer was 31.3 X 109/L, but the instrument voted out the differential and gave a platelet clump warning message. The technologist proceeded with several corrective actions as she was beginning to doubt the reported white count. She took the following steps:
• She physically checked the specimen for clots; there were none.
• She vortexed the sample, because according to the SOP at this hospital this was the optimal method when the platelet clumping flag appeared and there were no visible clots.
The CBC was repeated, and the WBC increased to 39.1 X 109/L and the platelet count was 178.0 X 109/L. The technologist decided to hold the CBC for further study and proceeded to make a differential. When she observed the differential, the white cell count appeared much lower, no platelet clumps were observed, but strange, foamy purple blobs were observed. While canvassing the laboratory for other specimens, the technologist noticed that the centrifuged coagulation samples on the same patient contained a 2-cm layer of what appeared to be lipemia but the rest of the plasma was clear. This is not the typical picture of lipemia. The technologist knew that something was wrong with the plasma, but she could not pinpoint the problem. At this point, the technologist cancelled the CBC and coagulation tests and called the emergency department to inform them of this action and inquire about the patient. Additional patient samples were also requested. The technologist was informed that the patient had Waldenstrom's macroglobulinemia. The samples were redrawn and run through the hematology analyzer again with a WBC of 12.1 X 109/L. The instrument again gave messages such as platelet clumps and interfering substances. A slide examination was performed, and again the white cell estimate appeared lower than the instrument-reported WBC. As a last step, the technologist per formed a manual white count and platelet
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218 Part III • White Cell Disorders
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