An Evaluation of Nucleated Red Blood Cell Count by an Automated Haematology Analyser- A Tertiary Centre Experience.

Corresponding Author:
Dr. Ruchee Khanna,
Department of Pathology,
Kasturba Medical College,
Manipal-576104, Manipal University,
Manipal, Karnataka, India.
E-mail: ruchee.khanna@manipal.edu

ABSTRACT

BACKGROUND

nRBCs also referred to as normoblasts are seen in the peripheral blood films in variable numbers; both in physiological as well as pathologic states. Enumeration of these cells by modern day automated analysers remains a challenge. We wanted to assess the precision of the Beckman Coulter LH 755 & 780 haematology analysers^TM in enumerating the nRBC count.

METHODS

This is a retrospective study conducted in the Clinical Laboratory and Haematology Division of Kasturba Hospital, Manipal over a 3-month period on the Beckman Coulter LH 755 & 780 haematology analysers^TM (Beckman Coulter Inc., Miami, FL, USA) after obtaining requisite clearance from the Institutional Ethics Committee. A data of 47,332 random blood samples run on the analysers was collected. Both descriptive and analytical statistics were performed using the SPSS software version 22.0^TM (Chicago, IL, USA). The sensitivity, specificity and kappa agreement were calculated using the same.

RESULTS

A total of 797 cases from the 47,332 samples showed a “flag” for nRBCs. Two Twenty of these cases were confirmed microscopically to have had nRBCs in the peripheral smear (true positives). 137 cases had nRBCs in the smear but were not definitively evaluated by the instrument (false negatives). A vast majority of the cases (577) did not reveal any nRBC on microscopic examination despite a flag generated by the machine (false positives). Additionally, a sensitivity of 27.6% and specificity of 99.7% were also noted. The kappa agreement was 0.376 which showed a fair agreement between the two methods.

CONCLUSIONS

The automated haematology analysers Beckman Coulter LH 755 & 780 were found to be less sensitive in adequately enumerating the nucleated red blood cells. The number of false positives can be reduced by noting the ‘cellular interference’ flag. A manual review of such smears is necessary to confirm or refute such instrument messages.

KEY WORDS

nRBCs, Analysers, Counting, Peripheral Smear