Pre-analytical issues in the haemostasis laboratory: guidance for the clinical laboratories

Abstract

Ensuring quality has become a daily requirement in laboratories. In haemostasis, even more than in other disciplines of biology, quality is determined by a pre-analytical step that encompasses all procedures, starting with the formulation of the medical question, and includes patient preparation, sample collection, handling, transportation, processing, and storage until time of analysis. This step, based on a variety of manual activities, is the most vulnerable part of the total testing process and is a major component of the reliability and validity of results in haemostasis and constitutes the most important source of erroneous or un-interpretable results.Pre-analytical errors may occur throughout the testing process and arise from unsuitable, inappropriate or wrongly handled procedures. Problems may arise during the collection of blood specimens such as misidentification of the sample, use of inadequate devices or needles, incorrect order of draw, prolonged tourniquet placing, unsuccessful attempts to locate the vein, incorrect use of additive tubes, collection of unsuitable samples for quality or quantity, inappropriate mixing of a sample, etc. Some factors can alter the result of a sample constituent after collection during transportation, preparation and storage.Laboratory errors can often have serious adverse consequences. Lack of standardized procedures for sample collection accounts for most of the errors encountered within the total testing process. They can also have clinical consequences as well as a significant impact on patient care, especially those related to specialized tests as these are often considered as “diagnostic”. Controlling pre-analytical variables is critical since this has a direct influence on the quality of results and on their clinical reliability. The accurate standardization of the pre-analytical phase is of pivotal importance for achieving reliable results of coagulation tests and should reduce the side effects of the influence factors. This review is a summary of the most important recommendations regarding the importance of pre-analytical factors for coagulation testing and should be a tool to increase awareness about the importance of pre-analytical factors for coagulation testing.

Pre‐analytical stability of coagulation parameters in plasma stored at room temperature

“…Storage conditions, storage time and temperature are some of the many variables that can affect the stability of coagulation factors and influence the results of coagulation assays . We studied the stability of aliquoted plasma samples stored at RT for up to 48 hours.…”

“…Understanding the potential impact of these variables on laboratory results is of great importance. Results affected by pre‐analytical errors can have a significant impact on patient outcomes, such as diagnosis or treatment . The Clinical and Laboratory Standards Institute (CLSI) guidelines (Document H21‐A5) state that whole blood samples or plasma samples, stored at room temperature (RT), for routine haemostasis tests or determination of coagulation factors should be analysed within 4 hours after sample collection, with exception of prothrombin time (PT) testing with stability up to 24 hours .…”

Multicenter in vitro thromboelastography and thromboelastometry standardization

“…There are various potential analytical and preanalytical sources of the variation observed here . We attempted to minimize sources of error we could control, including the analyzers, assay consumables, machine operators, and the samples.…”

Sources and solutions for spurious test results in coagulation

“…Occasionally, spurious results (SR) are observed, which unfortunately can lead to an incorrect diagnosis with harmful consequences . In addition to biologic variation (related to the physiology and pathology of the patient), the cause of SR can come from any facet of the laboratory testing process: Preanalytical Variables (inadequate blood samples, incorrect anticoagulants, inappropriate processing, and/or storage), Analytical and Technical Variables (factors pertaining to the testing methodology), and Postanalytical Variables (incorrect reference interval, misinterpretation by laboratorian or clinician) ).…”

“…A good understanding of the sources of laboratory errors aided by the establishment of procedures and policies to eliminate or at least reduce avoidable errors is paramount to good coagulation laboratory operations . Although the laboratory testing process is divided into three stages: preanalytical (including biological variation), analytical, and postanalytical (including interpretation), most SR occur in the preanalytical stage followed by SR in the analytical and postanalytical stages . Each stage has components that must be regulated to ensure a correct result and subsequent interpretation to minimize SR.…”