Can a digital smear review be helpful in the routine haematology laboratory?

This issue of the Journal of Laboratory Medicine focuses on current aspects of routine haematological diagnostics.

The differential blood count (CBC) is one of the most common tests performed in the routine clinical haematology laboratory. Depending on the patient population, more than 90 % of blood counts are now performed on automated analysers. Although only a few of these haematology analysers dominate the market, this does not mean that the results of morphological detection and classification of immature or pathologically altered blood cells are comparable. This is the conclusion of a comparative study of two leading instruments by Oprea et al. [1].

Abnormal differential blood counts are automatically flagged with warnings by the haematology analyser. Even if the proportion is low, an experienced haematology specialist is still required to check the suspicious blood counts by using conventional microscopy. This long-established procedure is labour-intensive, time-consuming and costly, which is why routine laboratories increasingly intend lowering the intervention limits.

Although routine smear review of all flagged samples with pathological changes of myelopoiesis does not necessarily contribute with additional information. Microscopic smears are often the only way to detect reactive and neoplastic changes in lymphocytes as well as congenital and acquired changes in erythrocytes and thrombocytes.

With the introduction of computerised and intranet-based digital microscopy [2], cost-effectiveness and turnaround-time of CBC improved significantly, especially if the samples were sent by general practitioners or remote hospitals. Corresponding data from Canada, confirming the results of other working groups, are reported by Mayes and colleagues [3] in this issue.

The idea of being able to maintain a 7/24 staffing level in the laboratory with well-trained haematology specialists is no longer possible in view of the increasing age-related retirement of technicians specialised in haematology and the cost-saving reduction in personnel. It is therefore necessary for newly recruited or existing staff to receive effective haematological and morphological training in the shortest possible time.

New training and practice methods in morphological haematology are therefore needed to replace the current training and practice on so-called demonstration microscopes, which can only be used by a limited number of individuals under the direct supervision of an experienced specialist.

Today, internet-based digital programmes such as the “Cellavision Proficiency Tool” enable less time-consuming morphological training for any number of interested individuals in a self-study format, without being tied to a laboratory workstation. In this issue, Ingalls [4] reports on such a training concept and the experience gained with it.

However, the conventional microscope cannot be completely replaced because the edge areas of a smear cannot be captured by the most common digital microscopy systems, as Jandel points out in his article [5]. At low leukocyte counts, digital microscopy can differentiate a greater number of cells and thus capture and document cell inclusions and nuclear changes that are not present in all cells [6].

The article by Strasser et al. [7] deals with a topic that differs from the morphological view but should certainly be of interest to practitioners: Myelodysplastic neoplasms have different transfusion requirements in advanced stages, which correlate with the type and number of mutations associated with the disease. According to the findings of this retrospective study, it may be possible to optimise the transfusion management in these patients.