Wednesday, April 30, 2014

WBC Correction for the Presence of Nucleated Red Blood Cells

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