ICSH guidance for internal quality control policy for blood cell counters.

This paper is a description of the ICSH guidance for internal quality control (IQC) policy for blood cell counters. It follows from and links to a separate ICSH review for such policies and practices. The ICSH has gathered information regarding the current state of practice through review of published guidance from regulatory bodies, a questionnaire to six major cell counter manufacturers and a survey issued to 191 diagnostic laboratories in four countries (China, the Republic of Ireland, Spain, and the United Kingdom) on their IQC practice and approach to the use of commercial IQC materials. This has revealed diversity both in guidance and in practice around the world. There is diversity in guidance from regulatory organizations in regard to IQC methods each recommends, clinical levels to use and frequency to run commercial controls, and finally recommended sources of commercial control materials. The diversity in practice among clinical laboratories spans the areas of IQC methods used, derivation of target values, and action limits used with commercial control materials, and frequency of running commercial controls materials. These findings and their implications for IQC Practice are addressed in this guidance document, which proposes a harmonized approach to address the issues faced by diagnostic laboratories.