Laboratory diagnosis has undergone several changes due to automation. Both equipment supplying and the introduction of quality assurance programs (QAP) have led to higher precision in tests. With the aim to promote quality control, the processing of biological samples comprises three phases: pre-analytical, analytical and post-analytical. Most errors occur in the pre-analytical phase. Thus, their determination and corresponding assessment maximize QAP efficiency. In this study, by means of a systematic review, which comprised 14 articles, we describe the main biological variations found in the pre-analytical phase at clinical laboratories. The biological parameters described in the review included glucose, cholesterol, triglycerides, enzymes and hormones. As far as venipuncture is concerned, a common error was the prolonged use of tourniquet. The main error causes were the following: storage time, tourniquet time, phlebotomy techniques, insufficient information to patients, incorrect blood/anticoagulant ratio, inadequate tubes, contaminated samples, medication and interlaboratory alterations. Our results corroborated other studies, although we did not find other investigations that specifically evaluated changes in the pre-analytical phase due to the use of medication. The most assessed biological parameters coincided with clinical tests. Accordingly, both the implementation of an efficient QAP and the development of professional awareness may prevent laboratory inaccuracies.
Pre-analytical; Quality control; Systematic review; Laboratory error
