Preanalytical Errors in Clinical Laboratory Testing at a Glance: Source and Control Measures

The accuracy of diagnostic results in clinical laboratory testing is paramount for informed healthcare decisions and effective patient care. While the focus has traditionally been on the analytical phase, attention has shifted towards optimizing the preanalytical phase due to its significant contribution to total laboratory errors. This review highlights preanalytical errors, their sources, and control measures to improve the quality of laboratory testing. Blood sample quality is a critical concern, with factors such as hemolysis, lipemia, and icterus leading to erroneous results. Sources of preanalytical errors encompass inappropriate test requests, patient preparation lapses, and errors during sample collection, handling, and transportation. Mitigating these errors includes harmonization efforts, education and training programs, automated methods for sample quality assessment, and quality monitoring. Collaboration between laboratory personnel and healthcare professionals is crucial for implementing and sustaining these measures to enhance the accuracy and reliability of diagnostic results, ultimately improving patient care.

Observations from the Proteomics Bench

Many challenges in proteomics result from the high-throughput nature of the experiments. This paper first presents pre-analytical problems, which still occur, although the call for standardization in omics has been ongoing for many years. This article also discusses aspects that affect bioinformatic analysis based on three sets of reference data measured with different orbitrap instruments. Despite continuous advances in mass spectrometer technology as well as analysis software, data-set-wise quality control is still necessary, and decoy-based estimation, although challenged by modern instruments, should be utilized. We draw attention to the fact that numerous young researchers perceive proteomics as a mature, readily applicable technology. However, it is important to emphasize that the maximum potential of the technology can only be realized by an educated handling of its limitations.

A two-sample approach to retrograde extrapolation of blood THC concentrations - Is it feasible?

BACKGROUND

Retrograde extrapolation of drug concentrations in blood can be relevant in cases of drug-impaired driving and is regularly used in forensic toxicology in Norway. Δ9-tetrahydrocannabinol (THC) has complex, multi-compartmental pharmacokinetics, which makes retrograde extrapolation of blood THC concentrations problematic. In the present study, we evaluated an approach to retrograde extrapolation in which momentary rates of decrease of THC were estimated from two consecutive blood samples in apprehended drivers.

MATERIAL AND METHODS

Data were collected from apprehended drivers in Norway 2000-2020. We included 548 cases in which THC was detected in two consecutive blood samples collected ≥ 20 min apart. THC concentrations were measured by GC-MS and UHPLC-MS/MS. In each case, THC concentrations and the time between the two sampling points (Δt) were used to estimate the rate constant k. The relationship between THC concentration and k was modelled by linear regression.

RESULTS

The median Δt was 31 min (interquartile range, IQR = 9). The median blood THC concentration was 2.4 μg/L (IQR = 3.4) at the first sampling point and 2.3 μg/L (IQR =3.1) at the second. The concentration decreased in 62% and increased in 38% of all cases. However, considering measurement uncertainty, the changes were not statistically significant in 87% of cases. The mean of k was 0.12 h-1, corresponding to an apparent t1/2 of 6.0 h. The t1/2 predicted from linear regression of k against THC concentration ranged from 0.93 to 13 h for the highest and lowest concentrations observed (36 and 0.63 μg/L, respectively). The time from driving to blood collection had a median of 1.7 h (IQR = 1.5), and did not correlate with k.

CONCLUSIONS

The apparent t1/2 of THC calculated from the mean of k was 6.0 h, which is shorter than the terminal elimination t1/2 suggested in previous population studies. This indicates that blood samples were often taken during the late distribution phase of THC. Because Δt was short relative to the rates of decrease expected in the late distribution and elimination phases, the underlying true concentration changes related to in vivo pharmacokinetics were small and masked by the relatively larger "false" changes introduced by random analytical and pre-analytical error. Therefore, individual values of k calculated from only two blood samples taken a short time apart are unreliable, and a two-sample approach to retrograde extrapolation of THC cannot be recommended.

Implementing Individualized quality control plans and managing risk at the point-of-care for molecular diagnostics

INTRODUCTION

Faster turnaround times can lead to rapid patient treatment. Implementing a point-of-care (POC) molecular COVID-19 test requires careful planning. In the POC setting, there are numerous operators and regular monitoring of their activities is key to the successful implementation of a POC molecular test. Test errors can arise from samples, operators, reagents, the testing system, and even from the environment. These sources of error should be considered when implementing a new test.

AREAS COVERED

We outline the importance of establishing well-defined policies for staff to follow at the preanalytic, analytic and postanalytic phases of SARS-CoV-2 testing. As these factors are crucial for the accuracy and reliability of the test results. The key discussion points are from the CLSI EP23-Ed2 document on developing individualized quality control plans and medical literature search engines such as EMBASE, MEDLINE and MedlinePlus.

EXPERT OPINION

The risk management principles applied when implementing nucleic acid POC tests can identify specific control processes to help mitigate common sources of error when conducting molecular testing at the POC.

Preanalytical Errors in a Hematology Laboratory: An Experience from a Tertiary Care Center

BACKGROUND

Laboratory errors arise at any stage of testing. Detecting these inaccuracies before results are revealed might delay diagnosis and treatment, causing patient distress. Here, we studied the preanalytical errors in a hematology laboratory.

METHODS

This one-year retrospective analysis was conducted at the laboratory of a tertiary care hospital and included information on blood samples that were taken for hematology tests from both outpatients and inpatients. Laboratory records included sample collection and rejection information. The type and frequency of preanalytical errors were expressed as a proportion of total errors and sample number. Microsoft Excel was utilized to enter data. The results were presented in the form of frequency tables.

RESULTS

This research included 67,892 hematology samples. For preanalytical errors, 886 samples (1.3%) were discarded. The most common preanalytical error was insufficient sample (54.17%), and the least common was an empty/damaged tube (0.4%). Erroneous samples in the emergency department were mostly insufficient and clotted, whereas pediatric sample errors were caused by insufficient and diluted samples.

CONCLUSION

Inadequate samples and clotted samples account for the vast majority of preanalytical factors. Insufficiency and dilutional errors were most frequent from pediatric patients. Adherence to best laboratory practices can drastically cut down on preanalytical errors.

Blood-based traumatic brain injury biomarkers - Clinical utilities and regulatory pathways in the United States, Europe and Canada

INTRODUCTION

Traumatic brain injury (TBI) is a major global health issue, resulting in debilitating consequences to families, communities, and health-care systems. Prior research has found that biomarkers aid in the pathophysiological characterization and diagnosis of TBI. Significantly, the FDA has recently cleared both a bench-top assay and a rapid point-of-care assays of tandem biomarker (UCH-L1/GFAP)-based blood test to aid in the diagnosis mTBI patients. With the global necessity of TBI biomarkers research, several major consortium multicenter observational studies with biosample collection and biomarker analysis have been created in the USA, Europe, and Canada. As each geographical region regulates its data and findings, the International Initiative for Traumatic Brain Injury Research (InTBIR) was formed to facilitate data integration and dissemination across these consortia.

AREAS COVERED

This paper covers heavily investigated TBI biomarkers and emerging non-protein markers. Finally, we analyze the regulatory pathways for converting promising TBI biomarkers into approved in-vitro diagnostic tests in the United States, European Union, and Canada.

EXPERT OPINION

TBI biomarker research has significantly advanced in the last decade. The recent approval of an iSTAT point of care test to detect mild TBI has paved the way for future biomarker clearance and appropriate clinical use across the globe.

Computer-Aided Medical Microbiology Monitoring Tool: A Strategy to Adapt to the SARS-CoV-2 Epidemic and That Highlights RT-PCR Consistency

Since the beginning of the COVID-19 pandemic, important health and regulatory decisions relied on SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) results. Our diagnostic laboratory faced a rapid increase in the number of SARS-CoV-2 RT-PCR. To maintain a rapid turnaround time, we moved from a case-by-case validation of RT-PCR results to an automated validation and immediate results transmission to clinicians. A quality-monitoring tool based on a homemade algorithm coded in R was developed, to preserve high quality and to track aberrant results. We present the results of this quality-monitoring tool applied to 35,137 RT-PCR results. Patients tested several times led to 4,939 pairwise comparisons: 88% concordant and 12% discrepant. The algorithm automatically solved 428 out of 573 discrepancies. The most likely explanation for these 573 discrepancies was related for 44.9% of the situations to the clinical evolution of the disease, 27.9% to preanalytical factors, and 25.3% to stochasticity of the assay. Finally, 11 discrepant results could not be explained, including 8 for which clinical data was not available. For patients repeatedly tested on the same day, the second result confirmed a first negative or positive result in 99.2% or 88.9% of cases, respectively. The implemented quality-monitoring strategy allowed to: i) assist the investigation of discrepant results ii) focus the attention of medical microbiologists onto results requiring a specific expertise and iii) maintain an acceptable turnaround time. This work highlights the high RT-PCR consistency for the detection of SARS-CoV-2 and the necessity for automated processes to handle a huge number of microbiological results while preserving quality.

Computer-Aided Medical Microbiology Monitoring Tool: A Strategy to Adapt to the SARS-CoV-2 Epidemic and That Highlights RT-PCR Consistency

Since the beginning of the COVID-19 pandemic, important health and regulatory decisions relied on SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) results. Our diagnostic laboratory faced a rapid increase in the number of SARS-CoV-2 RT-PCR. To maintain a rapid turnaround time, we moved from a case-by-case validation of RT-PCR results to an automated validation and immediate results transmission to clinicians. A quality-monitoring tool based on a homemade algorithm coded in R was developed, to preserve high quality and to track aberrant results. We present the results of this quality-monitoring tool applied to 35,137 RT-PCR results. Patients tested several times led to 4,939 pairwise comparisons: 88% concordant and 12% discrepant. The algorithm automatically solved 428 out of 573 discrepancies. The most likely explanation for these 573 discrepancies was related for 44.9% of the situations to the clinical evolution of the disease, 27.9% to preanalytical factors, and 25.3% to stochasticity of the assay. Finally, 11 discrepant results could not be explained, including 8 for which clinical data was not available. For patients repeatedly tested on the same day, the second result confirmed a first negative or positive result in 99.2% or 88.9% of cases, respectively. The implemented quality-monitoring strategy allowed to: i) assist the investigation of discrepant results ii) focus the attention of medical microbiologists onto results requiring a specific expertise and iii) maintain an acceptable turnaround time. This work highlights the high RT-PCR consistency for the detection of SARS-CoV-2 and the necessity for automated processes to handle a huge number of microbiological results while preserving quality.

Competitive Real-Time Near Infrared (NIR) Vein Finder Imaging Device to Improve Peripheral Subcutaneous Vein Selection in Venipuncture for Clinical Laboratory Testing

In this study, near-infrared (NIR) technology was utilized to develop a low-cost real-time near infrared (NIR) guiding device for cannulation. A portable device that can be used by medical practitioners and also by students for their skills development training in performing cannulation. Methods. First, is the development of a reflectance type optical vein finder using three (3) light emitting diode (LED) lights with 960 nm wavelength, complementary metal-oxide-semiconductor-infrared (CMOS-IR) sensor camera with 1920 × 1080 UXGA (1080P), IR filter set for the given wavelength, and an open-source image processing software. Second, is the actual in-vitro human testing in two sites: the arm and dorsal hand of 242 subjects. The following parameters were included, such as gender, age, mass index (BMI), and skin tone. In order to maximize the assessment process towards the device, the researchers included the arm circumference. This augmented subcutaneous vein imaging study using the develop vein finder device compared the difference in the captured vein images through visual and digital imaging approaches. The human testing was performed in accordance with the ethical standards of the Trinity University of Asia—Institutional Ethics Review Committee (TUA—IERC). Results. The NIR imaging system of the developed vein finder in this study showed its capability as an efficient guiding device through real-time vein pattern recognition, for both sites. Improved captured vein images were observed, having 100% visibility of vein patterns on the dorsal hand site. Fourteen (5.79%) out of 242 subjects reported non-visible peripheral subcutaneous veins in the arm sites. Conclusions. The developed vein finder device with the NIR technology and reflected light principle with low-energy consumption was efficient for real-time peripheral subcutaneous vein imaging without the application of a tourniquet. This might be utilized as a guiding device in locating the vein for the purpose of cannulation, at a very low cost as compared to the commercially available vein finders. Moreover, it may be used as an instructional device for student training in performing cannulation.

Six Sigma performance of quality indicators in total testing process of point-of-care glucose measurement: A two-year review

Objectives

The error rate in the total testing process (TTP) of point-of-care (POC) glucose measurement remains high although a total quality management system has been applied. Quality indicators (QIs) in the TTP of glucose meter were established via risk assessment. Their two-year Six Sigma values were reviewed for quality improvement.

Design

The TTP of POC glucose measurement was mapped to identify risks in key steps. The risks were assessed for their frequency and severity of impact on patient safety. Whenever possible, measurable data from the data management system and other sources was collected to establish QIs for risk monitoring. Average Six Sigma value of each QI in the last two years was calculated for acceptance and for determining corrective action.

Results

29 risks were identified in eight key steps of the TTP. Eight QIs were established for monitoring six risks and three QIs for two accepted risks were established for improving operator testing skill. The QIs had a good coverage to key steps. Two, five and four QIs showed Six Sigma values <3, 3-4 and >4 respectively. Six Sigma values of two QIs related to quality control (QC) testing were improved by using meters with accurate QC sample loading.

Conclusions

The establishment of QIs for glucose measurement by risk assessment with measurable data from the data management system and on Six sigma scale was effective, efficient, and manageable. Most of QIs’ Six Sigma values were between 3 and 5, which could be improved by using upgraded meters.

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The total testing process of POC glucose measurement was assessed to identify all risks that might impact patient safety.

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QIs that established from data management system monitored the risks related to all of the meters and operators.

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Six Sigma values of QIs provided a straightforward acceptance in their performance evaluation.

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Most of the Six Sigma values of QIs for glucose meters were between 3 and 5 under current total quality management system.

Preanalytical variables affecting the measurement of serum paraoxonase-1 activity in horses

Paraoxonase-1 (PON-1) activity is a new inflammatory and oxidative marker. Technical effects and biological factors could affect the accuracy of PON-1 activity measurement. We investigated the effects of storage at different temperatures, repeated freeze-thaw cycles, interferences from hemolytic, lipemic, and icteric samples, and seasonal effects on PON-1 activity in horses. We evaluated 2 substrates with an automated spectrophotometer. Ten equine serum samples were stored under different conditions. Although storage at room (21°C) or refrigeration (4°C) temperature induced a statistically significant decrease (p < 0.05) in PON-1 activity, this is not diagnostically relevant. PON-1 activity in frozen samples (-20°C) was stable for short-term storage; diagnostically significant (p < 0.01) fluctuations were observed after 1 mo. Four repeated freeze-thaw cycles were assessed, and all cycles affected PON-1 activity (p < 0.01); however, this was diagnostically significant only after the 4th cycle. Hemolysis induced an overestimation of PON-1 activity; lipemia and hyperbilirubinemia did not change PON-1 activity. Thirty-four horses were sampled monthly for 1 y, and PON-1 activity was higher in autumn (p < 0.05) and winter (p < 0.05) than in spring and summer.

Measurement uncertainty as a universal concept: can it be universally applicable in routine laboratory practice?

Measurement uncertainty (MU) of results is one of the basic recommended and accepted statistical methods in laboratory medicine, with which analytical and clinical evaluation of laboratory test quality is assessed. Literature data indicate that the calculation of MU is not a simple process, but that its assessment in daily laboratory practice should be reduced to routine and simple presentation, understandable to both laboratory professionals and physicians. In order to achieve this, it is necessary to understand the purpose of the test for which MU is to be determined. Various suggestions have been given for presentation of MU as a quantitative indicator of the quality of the final measurement result in the medical laboratory. Although MU refers to the final measurement result, this metrological concept reflects the entire laboratory measurement process. The data on estimated MU is used to interpret the measured numerical result, and represents quantitatively the quality of the measurement itself, i.e. how different are the results of multiple measurements of the analyte of interest in the same sample, as well as whether the method of determination itself is subjected to significant random and systematic deviation. Initially, in the metrological concept, the MU is viewed in relation to the true value of the analyte of interest. However, the true value of the analyte measured in the biological fluid matrix of the study population cannot be known. It is therefore considered the closest value obtained by the perfect method, for which the bias and inaccuracy, as measures of systematic and random error, are equal to zero, which is practically impossible to achieve in routine laboratory practice. Although current standards require accredited medical laboratories to estimate MU, none of these guidelines provide clear guidance on how this can be achieved in daily laboratory work. This review examines literary data and documents dealing with MU issues, but also highlights what additional terms and data should be considered when interpreting MU. This paper ultimately draws attention, and once again points out, that a simpler solution is needed for this universal concept to be formally and universally applicable in routine laboratory medicine practice.

Case report of spuriously low sodium and calcium in a 36-year-old male in primary care

An unseparated serum specimen for a 36-year-old male was received from primary care. The specimen arrived in the laboratory at Cork University Hospital one day after collection, as documented on the paper request card, and was promptly centrifuged. Analysis was delayed for three days due to operational constraints and serum indices were run at the same time as the biochemical analyses. Results showed a moderately haemolysed specimen with remarkably low concentrations of both sodium (119 mmol/L) and total calcium (1.15 mmol/L), with all other parameters within their appropriate reference intervals (RIs). The complete report was released electronically and both sodium and calcium results were phoned to, and acknowledged by, the requesting general practitioner (GP). Discussion between the medical scientists and clinical biochemist on duty raised the possibility that the specimen was significantly older than initially thought. Further discussion of results with the GP clarified that the documented time of collection corresponded with specimen receipt by the courier, rather than the time of phlebotomy. Thus, the specimen was 7 days old when received in the laboratory and 10 days old when analysed. This case illustrates the dangers of multiple convergent preanalytical errors. Laboratories should be mindful of the stability of analytes in unseparated blood and unusual patterns of results which might suggest a specimen is "old", and that this may coexist with erroneous request information. Any potential adverse effects on patient care were prevented in this case by laboratory vigilance.

Liquid materials for biomedical research: a highly IT-integrated and automated biobanking solution

Various information technology (IT) infrastructures for biobanking, networks of biobanks and biomaterial management are described in the literature. As pre-analytical variables play a major role in the downstream interpretation of clinical as well as research results, their documentation is essential. A description for mainly automated documentation of the complete life-cycle of each biospecimen is lacking so far. Here, the example taken is from the University Medical Center Göttingen (UMG), where the workflow of liquid biomaterials is standardized between the central laboratory and the central biobank. The workflow of liquid biomaterials from sample withdrawal to long-term storage in a biobank was analyzed. Essential data such as time and temperature for processing and freezing can be automatically collected. The proposed solution involves only one major interface between the main IT systems of the laboratory and the biobank. It is key to talk to all the involved stakeholders to ensure a functional and accepted solution. Although IT components differ widely between clinics, the proposed way of documenting the complete life-cycle of each biospecimen can be transferred to other university medical centers. The complete documentation of the life-cycle of each biospecimen ensures a good interpretability of downstream routine as well as research results.

Vein Pattern Locating Technology for Cannulation: A Review of the Low-Cost Vein Finder Prototypes Utilizing near Infrared (NIR) Light to Improve Peripheral Subcutaneous Vein Selection for Phlebotomy

One of the most common means for diagnosis is through medical laboratory testing, which primarily uses venous blood as a sample. This requires an invasive method by cannulation that needs proper vein selection. The use of a vein finder would help the phlebotomist to easily locate the vein, preventing possible pre-analytical error in the specimen collection and even more discomfort and pain to the patient. This paper is a review of the scientific publications on the different developed low-cost vein finder prototypes utilizing camera assisted near infrared (NIR) light technology. Methods: Electronic databases were searched online, these included PubMed (PMC), MEDLINE, Science Direct, ResearchGate, and Institute of Electrical and Electronics Engineers (IEEE) Xplore digital library. Specifically, publications with the terms vein finder prototype, NIR technology, vein detection, and infrared imaging were screened. In addition, reference lists were used to further review related publications. Results: Cannulation challenges medical practitioners because of the different factors that can be reduced by the utilization of a vein finder. A limited number of publications regarding the assessment of personnel performing cannulation were observed. Moreover, variations in methodology, number of patients, type of patients according to their demographics and materials used in the assessment of the developed prototypes were noted. Some studies were limited with regard to the actual human testing of the prototype. Conclusions: The development of a low-cost effective near infrared (NIR) vein finder remains in the phase of improvement. Since, it is being challenged by different human factors, increasing the number of parameters and participants/human for actual testing of the prototypes must also be taken into consideration for possible commercialization. Finally, it was noted that publications regarding the assessment of the performance of phlebotomists using vein finders were limited.

Retrospective study showed that blood sampling errors risked children's well-being and safety in a Swedish paediatric tertiary care

AIM

Blood analyses containing preanalytical errors (PAEs) are hazardous for patients. This study investigated the frequency of PAEs in blood analysis and the corresponding quality indicators of the sampling process in Swedish paediatric tertiary care.

METHODS

Data were retrieved from the laboratory at Astrid Lindgren Children's Hospital between 2013 and 2014. Preanalytical blood sampling performance was analysed according to the Six Sigma scale, ranging from 0 to 6 (933 137-3.4 defects per million [DPM]).

RESULTS

Of the 1 148 716 analyses, 61 656 (5.4%) were rejected due to PAEs. The PAEs ranged between hospital specialities from 1.9 to 9.4% (p < 0.001) and work shift times, from 6.0% in the day to 5.7% in the evening and 4.3% at night (p values <0.001). Clotting was the most prominent error (51.3%), affecting mostly haematology and coagulation analyses. Incorrectly filled samples represented almost 25% of all PAEs, with effects on chemistry, haematology and coagulation analyses. The sigma score for the overall preanalytical phase (3.2) corresponded to 44 565 DPM.

CONCLUSION

Samples with PAEs were frequently clotted and insufficiently filled, and the distribution of errors varied within working shifts and specific analyses. The overall quality control in paediatric blood sampling was barely acceptable.

Internal quality assurance in diagnostic microbiology: A simple approach for insightful data

Given the importance of microbiology results on patient care, high quality standards are expected. Internal quality assurance (IQA) could mitigate the limitations of internal quality control, competency assessment and external quality assurance, adding a longitudinal insight, including pre- and post-analytical steps. Here, we implemented an IQA program in our clinical microbiology facilities with blind resubmission of routine samples during 22 months. One-hundred-and-twenty-one out of 123 (98.4%) serological analyses and 112 out of 122 (91.8%) molecular analyses were concordant. Among the discordances in molecular biology analyses, 6 results were low positive samples that turned out negative, likely due to stochastic repartition of nucleic acids. Moreover, one identified retranscription error led us to implement automated results transmission from the Applied Biosystems instruments to the laboratory information system (LIS). Regarding Gram stain microscopy, 560 out of 745 (75.2%) of compared parameters were concordant. As many as 67 out of 84 (79.8%) pairs of culture results were similar, including 16 sterile pairs, 27 having identical identification or description and semi-quantification and 24 only showing variations in semi-quantification with identical description or identification of colonies. Seventeen pairs had diverging identification or description of colonies. Culture was twice only done for one member of the pairs. Regarding antibiotic susceptibility testing, a major discrepancy was observed in 5 out of 48 results (10.4%). In conclusion, serological tests were highly reproducible. Molecular diagnosis also revealed to be robust except when the amounts of nucleic acids present in the sample were close to the limits of detection. Conventional microbiology was less robust with major discrepancies reaching 39.5% of the samples for microscopy. Similarly, culture and antibiotic susceptibility testing were prone to discrepancies. This work was ground for reconsidering multiples aspects of our practices and demonstrates the importance of IQA to complete the other quality management procedures.

Novel Opportunities for Improving the Quality of Preanalytical Phase. A Glimpse to the Future?

The preanalytical phase is crucial for assuring the quality of in vitro diagnostics. The leading aspects which contribute to enhance the vulnerability of this part of the total testing process include the lack of standardization of different practices for collecting, managing, transporting and processing biological specimens, the insufficient compliance with available guidelines and the still considerable number of preventable human errors. As in heavy industry, road traffic and aeronautics, technological advancement holds great promise for decreasing the risk of medical and diagnostic errors, thus including those occurring in the extra-analytical phases of the total testing process. The aim of this article is to discuss some potentially useful technological advances, which are not yet routine practice, but may be especially suited for improving the quality of the preanalytical phase in the future. These are mainly represented by introduction of needlewielding robotic phlebotomy devices, active blood tubes, drones for biological samples transportation, innovative approaches for detecting spurious hemolysis and preanalytical errors recording software products.