Laboratory Diagnostics and Quality of Blood Collection

Abstract

Diagnostic blood samples collected by phlebotomy are the most common type of biological specimens drawn and sent to laboratory medicine facilities for being analyzed, thus supporting caring physicians in patient diagnosis, follow-up and/or therapeutic monitoring. Phlebotomy, a relatively invasive medical procedure, is indeed critical for the downstream procedures accomplished either in the analytical phase made in the laboratory or in the interpretive process done by the physicians. Diagnosis, management, treatment of patients and ultimately patient safety itself can be compromised by poor phlebotomy quality. We have read with interest a recent article where the authors addressed important aspects of venous blood collection for laboratory medicine analysis. The authors conducted a phlebotomy survey based on the Clinical and Laboratory Standard Institute (CLSI) H03-A6 document (presently replaced by the GP41-A6 document) in three government hospitals in Ethiopia to evaluate 120 professionals (101 non-laboratory professionals vs. 19 laboratory professionals) as regards the venous blood collection practice. The aim of this mini (non-systematic) review is to both take a cue from the above article and from current practices we had already observed in other laboratory settings, and discuss four questionable activities performed by health care professionals during venous blood collection. We refer to: i) diet restriction assessment; ii) puncture site cleansing; iii) timing of tourniquet removal and; iv) mixing specimen with additives.

Keywords: blood specimen collection; medical errors; patient safety; phlebotomy; specimen handling; tourniquet.

Figures

Figure 1

Schematic representation of the effects of stasis induced by tourniquet application on blood constituents. Normal flow of blood through an unobstructed vein (Figure 1-A). The obstruction due to tourniquet reduces blood flow thus creating venous stasis (Figure 1-B) with net efflux of water from the vessel to the interstice. Elements of low molecular mass diffuse with water whereas high molecular weight compounds and cells concentrate in the vein.