Pre-analytic phase in molecular biology: criticism and non-compliance management

Introduction: During workflow in Laboratories the most delicate and important step is pre-analytic sample treatment because it involves more than one operator of the same structure and often different health services. In fact, the biological materials used for the diagnosis should be collected, sent and properly treated before the analytic phase. Correct methods for collecting and handling biological materials, including guidelines to users of laboratory services, improve performance of Laboratory testing activity. In the pre-analytic phase the operators check sample integrity, and prepare the sample for the subsequent analytic phase: in all these steps monitoring and control of “non- compliance” is crucial. Methods: During 2007-2008 we created a “non- compliance” check-list, to monitor errors which occurred in different sectors of the preanalytic phase, particularly in the nucleic acid extraction step. These “non-compliances” are analysed to identify and to remove errors, adopting preventive and corrective proceedings. Since 2008 we have been using DNA/RNA internal controls synthesized in our Laboratory. They can be amplified by the same primers and recognized by different probes. Results: Examination of the “non compliance” check-list for molecular biology investigations shows that the percentage of urine repeat samples decreased from 17% to 2% and the percentage of stool repeat samples from 27% to 2%. Regarding use of internal controls, they allow the assessment of inhibitory factors that can prevent gene amplification. Conclusions: Monitoring “non-compliance” cases and dividing them by typology allow us identifying the most frequent causes of incorrect sample handling, as a non optimal procedure of pre-treatment, thus improving the pre-analytic phase. Therefore by monitoring the preanalytic phase we can prevent the introduction of confounding factors that may negatively influence the accuracy of results and their interpretation. Before proceeding to gene amplification, biological samples must be properly purified to eliminate lipids, proteins, polysaccharides and other potential inhibitors of DNA polymerase.