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Left Shift 1+ flag for the detection of band neutrophils: interlaboratory variations and recommendations for the
F Weerkamp1, P H Taal, B A De Boer
1Department of Clinical Chemistry, Maasstad Ziekenhuis, Rotterdam, The Netherlands.
Insights
The left shift (LS) 1+ flag on hematology analyzers can help reduce manual blood cell counts. Optimizing its use decreases unnecessary microscopic reviews in diagnostic labs.
Area of Science:
- Hematology
- Clinical Pathology
- Laboratory Medicine
Background:
- Manual leukocyte differential analysis is time-consuming in routine diagnostics.
- Strict criteria are needed to determine when manual differentials are necessary.
- The left shift (LS) 1+ flag indicates the presence of band neutrophils, potentially streamlining workflows.
Purpose of the Study:
- To evaluate the utility of the LS 1+ flag from ADVIA hematology analyzers.
- To provide recommendations for optimizing the use of the LS 1+ flag in diagnostic laboratories.
- To reduce the workload associated with manual leukocyte differential counts.
Main Methods:
- The LS 1+ flag from ADVIA 120 and 2120 analyzers was assessed in 6 Dutch hospital laboratories.
- Microscopic examination determined band neutrophil percentages in 2683 samples with an LS 1+ flag.
- Inter-laboratory variation in band cell assessment was analyzed using standardized neutrophil images.
Main Results:
- 18% of samples with only an LS 1+ flag showed 5% or more band neutrophils.
- Significant inter-laboratory differences were observed in LS 1+ flag frequency and band neutrophil counts.
- Factors influencing the LS 1+ flag included microscopist counting, differential request specificity, and sample storage.
Conclusions:
- Critical control over factors affecting the LS 1+ flag can reduce microscopic sample reviews.
- Optimizing LS 1+ flag usage is valuable for routine differentials across various hematology analyzers.
- Standardized protocols can enhance the reliability and efficiency of automated flagging systems.
Introduction:
Microscopic differential analysis of leukocytes is a time-consuming activity for routine diagnostic laboratories. The criteria used to decide whether a manual differential should be performed should therefore be as strict as possible. The goal of this investigation was to give recommendations for the use of the left shift (LS) 1+ flag, which signals the presence of band neutrophils.
Methods:
The LS1+ flag of the ADVIA 120 and 2120 hematology analyzers was evaluated in 6 peripheral hospital laboratories in the Netherlands. In 2683 samples with exclusively a LS1+ flag, the percentage of band neutrophils were determined microscopically. A set of photographs of neutrophils were used to examine the differences between laboratories in the assessment of band cells.
Results:
In 18% of all samples with only a LS1+ flag, 5% or more band neutrophils were found. However, this percentage differed greatly between laboratories, as did the proportion of samples that received a LS1+ flag. Several factors were found to influence the amount and accuracy of the LS1+ alarm, i.e. band neutrophil counting by microscopists, specificity of request for leukocyte differentials, percentage of general practitioners requesting a leukocyte differential, and sample storage. Based on these findings, a number of recommendations were formulated.
Conclusion:
Critical control of the factors influencing the LS1+ flag can significantly decrease the number of microscopic samples to be reviewed and may be valuable for every laboratory performing routine differentials, using any type of hematology analyzer.
