Internal Quality Control in the Haematology Laboratory: Practices and Challenges

Abstract

Background: Internal quality control (IQC) is central to reliable haematology testing because plausible analytical results may still be sufficiently inaccurate to affect clinical decisions. Effective IQC therefore requires more than routine testing of commercial controls and should be integrated with analyser surveillance, specimen quality, staff competence, reagent management, equipment maintenance and result validation. Objective: This review examines the principles and routine practices of IQC in haematology laboratories, including statistical interpretation, automated and manual procedures, and common implementation challenges, with attention to resource-constrained settings. Main Discussion: A sustainable IQC programme requires a written, risk-based plan that defines controlled measurands, control levels, testing frequency, target means, standard deviations, acceptance limits, review responsibilities and responses to failure. Levey–Jennings charts and appropriate statistical rules should be interpreted alongside analyser flags, background checks, carry-over assessment, patient-based monitoring, delta checks and blood-film review. Manual cell counts, haemoglobin methods, erythrocyte sedimentation rate, morphology and coagulation testing require method-specific controls and careful management of observer and procedural variation. Conclusion: Major challenges include the cost and intermittent supply of control materials, unstable electricity, environmental limitations, delayed equipment service, inadequate staffing, weak documentation and inappropriate responses to failed controls. Improvement depends on management commitment, locally verified procedures, disciplined troubleshooting, regular trend review and external quality assessment.