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n Medical Technology SA - Reducing unnecessary blood smear examinations : can Sysmex blood cell analysers help? : peer reviewed original article
Background The microscopic assessment of a peripheral blood smear is an essential diagnostic tool. Many haematology laboratories currently assess smears microscopically for every full blood count request, many of which may however be assessed unnecessarily - an important consideration in resource-constrained settings. Modern blood cell analysers are increasing in sophistication and can flag abnormal specimens that may require microscopy.
Objectives To evaluate the flagging efficiency of the Sysmex haematology analysers and to determine whether this potentially labour-saving technology could assist in safely reducing the number of unnecessary microscopic blood smear assessments.
Methods A total of 427 full blood count specimens collected consecutively over a 24-hour period at NHLS Pelonomi and NHLS Kimberley, were evaluated microscopically and compared with the instruments' abilities to flag potential morphological abnormalities.
Results The Sysmex blood cell analysers flagged 63.7% of specimens as "positive" and 36.3% as "negative". After microscopy, false positive flags were found to constitute 18.5% and false negative flags 5.4% of the total number of smears reviewed, giving a total of 23.9% incorrect assessments. No false negative flag was clinically critical.
Conclusion False negative results occurring with the Sysmex instruments' flagging systems in our settings are relevant, although not critical. The potential time and monetary savings of a flagging-based smear review policy may weigh heavier than occasional false negatives. In the African milieu, where laboratories are faced with the challenges posed by staff- and other shortages, relying on instrumentation flagging to guide smear review policy should be considered.
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