WBC Correction for the Presence of Nucleated Red Blood Cells (nRBCs)
Due to the fact that nRBCs present in the whole blood are not lysed by the diluting fluid when a WBC count is performed and the fact that most automated analyzers will miscount them as small round lymphocytes, a WBC correction needs to be performed.
In most of the cases, when an instrument/automated analyser "flagged" for nRBCs seen/observed/suspected, a thin blood smear will be performed for manual microscopy. If there are more than 5 nRBCs seen per 100 WBC’s after performing a differential count, the total white count MUST be corrected for the presence of these nucleated red cells. The formula is as follows:
Uncorrected WBC count X 100 = corrected WBC count (mm3)
number of nRBC’s per 100 WBC’s + 100
The count should be reported as a corrected WBC count..
Example: 8 nucleated red blood cells are seen while performing a differential on a smear of peripheral blood from a patient. The WBC count reported by the Coulter Counter was 17,400 mm3. Hence to calculate the actual leukocyte count, the above formula will be activated
17,400 X 100 = 1740000 = 16,111 mm3 corrected
8 + 100 108