Short-term venous stasis influences routine coagulation testing

Clinical application of a fully automated blood collection robot and its assessment of blood collection quality of anticoagulant specimens

Background and objectives

To investigate the application of intelligent puncture blood collection robots in anticoagulated blood specimens, the satisfaction of subjects with the two blood collection methods, and the feasibility of intelligent blood collection devices to replace manual blood collection methods in clinical work.

Materials and methods

A total of 154 volunteers from Zhongshan Hospital Fudan University were recruited to compare the test results of anticoagulant blood samples between blood collection robot and manual blood collection, a questionnaire was used to inquire about the volunteers' feelings about the two blood collection methods; the blood collection data of 6,255 patients willing to use the robot for blood collection were collected to analyze the success rate of blood collection.

Results

The blood collection robot is superior to manual specimen collection in terms of volume and pain of specimen collection, and the puncture success rate is 94.3%. The anticoagulated blood specimens collected by the robot had 11 indexes statistically different from the results of manual blood collection, but the differences did not affect the clinical diagnosis and prognosis.

Conclusion

The intelligent robotic blood collection is less painful and has better acceptance by patients, which can be used for clinical anticoagulated blood specimen collection.

Impact of specific preclinical variables on coagulation biomarkers in cancer-associated thrombosis

Coagulation biomarkers are being actively studied for their diagnostic and prognostic value in patients with venous thromboembolism and cancer, as well as in the study of pathogenic mechanisms between cancer and thrombosis. For the results of such studies to be accurate and reproducible, attention must be paid to minimize sources of error in all phases of testing. The pre-analytical phase of laboratory testing is known to be fraught with the majority of errors. Coagulation testing is particularly susceptible to conditions during collection, processing, transport and storage of specimens which can lead to clinically significant errors in results. In addition, changes in pre-analytical conditions can impact different biomarkers differently. Therefore, research studies investigating coagulation biomarkers must carefully standardize not just the analytical phase, but also the pre-analytical phase of testing to ensure accuracy and reliability. We briefly review the impact of pre-analytical conditions on coagulation testing in general, and on specific biomarkers in cancer and thrombosis. In addition, we provide recommendations to reduce pre-analytical errors by developing and sharing standard operating procedures that specifically target standardization of methodologies for collecting specimens and measuring current and emerging coagulation biomarkers in cancer studies.

International Council for Standardisation in Haematology (ICSH) recommendations for collection of blood samples for coagulation testing

This guidance document has been prepared on behalf of the International Council for Standardisation in Haematology (ICSH). The aim of the document is to provide guidance and recommendations for collection of blood samples for coagulation tests in clinical laboratories throughout the world. The following processes will be covered: ordering tests, sample collection tube and anticoagulant, patient preparation, sample collection device, venous stasis before sample collection, order of draw when different sample types need to be collected, sample labelling, blood-to-anticoagulant ratio (tube filling) and influence of haematocrit. The following areas are excluded from this document, but are included in an associated ICSH document addressing processing of samples for coagulation tests in clinical laboratories: sample transport and primary tube sample stability; centrifugation; interfering substances including haemolysis, icterus and lipaemia; secondary aliquots-transport and storage; and preanalytical variables for platelet function testing. The recommendations are based on published data in peer-reviewed literature and expert opinion.

Joint EFLM-COLABIOCLI Recommendation for venous blood sampling

This document provides a joint recommendation for venous blood sampling of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group for Preanalytical Phase (WG-PRE) and Latin American Working Group for Preanalytical Phase (WG-PRE-LATAM) of the Latin America Confederation of Clinical Biochemistry (COLABIOCLI). It offers guidance on the requirements for ensuring that blood collection is a safe and patient-centered procedure and provides practical guidance on how to successfully overcome potential barriers and obstacles to its widespread implementation. The target audience for this recommendation are healthcare staff members directly involved in blood collection. This recommendation applies to the use of a closed blood collection system and does not provide guidance for the blood collection with an open needle and syringe and catheter collections. Moreover, this document neither addresses patient consent, test ordering, sample handling and transport nor collection from children and unconscious patients. The recommended procedure is based on the best available evidence. Each step was graded using a system that scores the quality of the evidence and the strength of the recommendation. The process of grading was done at several face-to-face meetings involving the same mixture of stakeholders stated previously. The main parts of this recommendation are: 1) Pre-sampling procedures, 2) Sampling procedure, 3) Post-sampling procedures and 4) Implementation. A first draft of the recommendation was circulated to EFLM members for public consultation. WG-PRE-LATAM was also invited to comment the document. A revised version has been sent for voting on to all EFLM and COLABIOCLI members and has been officially endorsed by 33/40 EFLM and 21/21 COLABIOCLI members. We encourage professionals throughout Europe and Latin America to adopt and implement this recommendation to improve the quality of blood collection practices and increase patient and workers safety.

Accuracy of laboratory tests collected at referring hospitals versus tertiary care hospitals for acute stroke patients

BACKGROUND

The standard treatment of acute ischemic stroke patients is thrombolytic therapy within 60 minutes of a patient's arrival in stroke center hospitals. Based on the policy of the Lampang Referral System Committee, blood samples of suspected stroke patients need to be collected before transfer to the stroke center (Lampang Hospital). It was still questionable as to whether these blood samples are valid for clinical use and the present study aimed to confirm or deny their validity.

METHODS

A diagnostic study was conducted from June 2015 to May 2016. After exclusion, 340 patients were deemed eligible for analysis. Blood samples were collected just before normal saline infusion at referring hospitals and stored in blood collecting tube boxes set during transportation. At the stroke center, informed consents was requested, blood samples were re-collected to serve as a 'gold standard'. Prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT), platelet count, hemoglobin (Hb), hematocrit (Hct), blood urea nitrogen (BUN), and creatinine (Cr) were compared using paired t-tests. Binary regression was used to analyze for accuracy (%) to adjust for extraneous influences and was presented by modified Bland-Altman plots.

RESULTS

The laboratory results of referring hospitals vs. the stroke center were: PT, 12.4±3.2 vs. 12.5±3.0 sec; INR: 1.0±0.3 vs. 1.0±0.3; and platelet count: 239.8±77.1 vs. 239.8±74.8 (x103/μL). The adjusted accuracy of the PT, INR, and platelet counts were 96.8%, 96.8%, and 95.3% respectively.

CONCLUSION

Laboratory tests from referring hospital were determined to be valid. Blood samples should thus be collected at referring hospitals in order to avoid unnecessary blood collection at the stroke center.

Preanalytical investigations of phlebotomy: methodological aspects, pitfalls and recommendations

Phlebotomy is often addressed as a crucial process in the pre-analytical phase, in which a large part of laboratory errors take place, but to date there is not yet a consolidated methodological paradigm. Seeking literature, we found 36 suitable investigations issued between 1996 and 2016 (April) dealing with the investigation of pre-analytical factors related to phlebotomy. We found that the largest part of studies had a cohort of healthy volunteers (22/36) or outpatients (11/36), with the former group showing a significantly smaller median sample size (N = 20, IQR: 17.5-30 and N = 88, IQR: 54.5-220.5 respectively, P < 0.001). Moreover, the largest part investigated one pre-analytical factor (26/36) and regarded more than one laboratory test (29/36), and authors preferably used paired Student’s t-test (17/36) or Wilcoxon’s test (11/36), but calibration (i.e. sample size calculation for a detectable effect) was addressed only in one manuscript. The Bland-Altman plot was often the preferred method used to estimate bias (12/36), as well as the Passing-Bablok regression for agreement (8/36). However, often papers did assess neither bias (12/36) nor agreement (24/36). Clinical significance of bias was preferably assessed comparing to a database value (16/36), and it resulted uncorrelated with the size of the effect produced by the factor (P = 0.142). However, the median effect size (ES) resulted significantly larger if the associated factor was clinically significant instead of non-significant (ES = 1.140, IQR: 0.815-1.700 and ES = 0.349, IQR: 0.228-0.531 respectively, P < 0.001). On these evidences, we discussed some recommendations for improving methodological consistency, delivering reliable results, as well as ensuring accessibility to practical evidences.

Pre-analytical phase management: a review of the procedures from patient preparation to laboratory analysis

The pre-analytical phase encompasses all the procedures before the start of laboratory testing. This phase of the testing process is responsible for the majority of the laboratory errors, since the related procedures involve many sorts of non-laboratory professionals working outside the laboratory setting, thus without direct supervision by the laboratory staff. Therefore, either correct organization or management of both personnel and procedures that regard blood specimen collection by venipuncture are of fundamental importance, since the various steps for performing blood collection represent per se sources of laboratory variability. The aim of this (non-systematic) review addressed to healthcare professionals is to highlight the importance of blood specimen management (from patient preparation to laboratory analyses), as a tool to prevent laboratory errors, with the concept that laboratory results from inappropriate blood specimens are inconsistent and do not allow proper treatment nor monitoring of the patient.

Preanalytical Issues in Hemostasis and Thrombosis Testing

Hemostasis testing is critical to many hemorrhagic and thrombotic disorders, wherein laboratory diagnostics can provide critical information for diagnosis, prognostication, and therapeutic monitoring. Due to this crucial role in modern medicine, hemostasis tests should be carried out at their highest degree of quality, thus encompassing standardization and monitoring of all phases of the testing process. It is now clearly established that the preanalytical phase is the most critical and vulnerable part of the total testing process, since up to 70% of diagnostic errors are due to highly manual activities encompassing patient preparation and collection of biological samples, as well as handling, transportation, preparation and storage of blood specimens. Due to the peculiar sample matrix required for hemostasis testing (i.e., plasma anticoagulated with buffered sodium citrate), additional critical issues may impair the reliability of these tests. Therefore, this article aims to provide an updated overview of the most important preanalytical variables that may ultimately impair the quality of hemostasis and thrombosis testing.

Phlebotomy, a bridge between laboratory and patient

The evidence-based paradigm has changed and evolved medical practice. Phlebotomy, which dates back to the age of ancient Greece, has gained experience through the evolution of medicine becoming a fundamental diagnostic tool. Nowadays it connects the patient with the clinical laboratory dimension building up a bridge. However, more often there is a gap between laboratory and phlebotomist that causes misunderstandings and burdens on patient safety. Therefore, the scope of this review is delivering a view of modern phlebotomy to "bridge" patient and laboratory. In this regard the paper describes devices, tools and procedures in the light of the most recent scientific findings, also discussing their impact on both quality of blood testing and patient safety. It also addresses the issues concerning medical aspect of venipuncture, like the practical approach to the superficial veins anatomy, as well as the management of the patient's compliance with the blood draw. Thereby, the clinical, technical and practical issues are treated with the same relevance throughout the entire paper.

Are Inflammatory Biomarkers Increased in Varicose Vein Blood?

OBJECTIVES

To test for the presence of inflammatory biomarkers in blood taken from varicose veins versus antecubital blood of the same patient and compare this to levels in healthy controls.

METHODS

Using a multiplex biochip array method (Randox, United Kingdom), the interleukins (ILs) IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, and IL-10; vascular endothelial growth factor; interferon γ, tumor necrosis factor α ; monocyte chemotactic protein 1 (MCP-1); and epidermal growth factor were measured in citrated plasma samples drawn from the arms and legs of 24 patients with varicose veins and 24 controls.

RESULTS

Expressed as median (interquartile range) in pg/mL, leg samples from patients with varicose veins had significantly higher levels of IL-8 and MCP-1 compared to their own arm samples (IL-8: local 2.3 [1.71-3.3] vs systemic 2.3 [1.62-2.98], P = .023; MCP-1: local 114.42 [84.29-139.05] vs systemic 103.56 [79.75-126.42], P < .0005). This was not observed in the control group. Leg samples from both patients with varicose vein and controls had higher levels of IL-6 compared to their own arm samples (patients: local 1.67 [0.82-4.48] vs systemic 1.24 [0.58-3.26], P = .002; controls: local 1.23 [0.83-1.7] vs systemic 1.03 [1.7-1.52], P = .005). No significant differences were detected with the other biomarkers.

CONCLUSIONS

Blood drawn from the site of varicose veins appears to have significantly increased concentrations of IL-6, IL-8, and MCP-1 when compared to the same patient's arm blood. This supports the hypothesis that inflammation is activated from the tissues drained by the varicose veins.

Endogenous pro-thrombotic biomarkers from the arm and leg may not have the same value

Objective

Assessments of endogenous pro-thrombotic biomarkers are performed invariably on arm blood. However, the commonest site for thrombosis is in the leg. A leg blood sample may reflect local pro-thrombotic processes more accurately than systemic arm blood. The aim was to determine whether pro-thrombotic biomarkers from standard venous arm samples differed significantly from leg samples.

Method

Concurrent blood samples were taken from an ankle/lower calf varicose vein and an ante-cubital vein in 24 patients awaiting laser treatment as well as age approximated and sex matched healthy controls without venous disease. The following assays were performed: thrombin–antithrombin (ng/ml), antithrombin (%) activity, microparticles (nM), fibrinogen (mg/dl), prothrombin fragment 1.2 (F1.2) (pM) and P-selectin (ng/ml).

Results

Expressed as median (inter-quartile range). Significant arm/leg differences were observed in thrombin–antithrombin, antithrombin, prothrombin fragment 1.2 and P-selectin. The legs of patients had significantly reduced antithrombin activity and P-selectin concentrations compared to their arms (leg: 101 (90–108) versus arm: 112 (99–126), P = 0.001 and leg: 42 (26–52) versus 45 (27–52), P = 0.044, respectively). Control leg samples had significantly increased thrombin–antithrombin and P-selectin compared to control arm samples (leg: 2.1 (0.9–3.2) versus arm: 0.8 (0.5–1.7), P = 0.015 and leg: 36 (24–50) versus arm: 30 (23–41), P = 0.007, respectively). However, the control legs had significantly reduced F1.2 (leg: 265 (230–333) versus arm: 299 (236–361), P = 0.028). No significant arm/leg differences were detected in the microparticle or fibrinogen levels.

Conclusions

These findings indicate that venous arm blood is significantly different from venous leg blood in four out of six biomarkers studied. Recognition of local venous leg sampling as a site for investigation may unravel why the leg has a greater predisposition to thrombosis and lead the way towards an arm/leg differential test.

d-Dimer Levels are Significantly Increased in Blood Taken From Varicose Veins Compared With Antecubital Blood From the Same Patient

d-Dimer is a prothrombotic biomarker and a very sensitive measure of endogenous fibrinolysis. It is used as a screening test for suspected deep vein thrombosis. This study investigated whether d-dimer levels were increased in the varicose veins of patients in comparison to their own arm samples. Patients, n = 24, 17 male, age 45 (25-91), C2-6, awaiting saphenous laser ablation were compared to matched controls, n = 24, 17 male, age 42 (24-89). Concurrent venous blood samples were taken from the arm and a lower calf/ankle (varicose) vein. The median (interquartile range) d-dimer (ng/mL) level was significantly greater in the ankle than in the arm blood of the same patient at 319 (164-631) versus 281 (167-562), P = .003, Wilcoxon. This did not occur in the controls at 269 (80-564) versus 262 (106-526), P = .361, Wilcoxon. The results indicate increased endogenous fibrinolysis in varicose veins compared with arm blood. This suggests there is more thrombotic activity or dissolution of formed subclinical fibrin thrombus which may explain the association of varicose veins with superficial vein thrombosis. This contrasts with earlier studies reporting a local reduction in fibrinolysis in venous disease.

The effective reduction of tourniquet application time after minor modification of the CLSI H03-A6 blood collection procedure

Introduction:

The phlebotomists’ procedures are a still source of laboratory variability. The aim of this study was to verify the efficacy of minor modification in procedure for collection of diagnostic blood specimens by venipuncture from CLSI H03-A6 document is able to reduce the tourniquet application time.

Materials and methods:

Thirty phlebotomists were invited to participate. Each phlebotomist was trained individually to perform the new venipuncture procedure that shortens the time of tourniquet release and removal. The phlebotomy training program was delivered over 8h. After training, all phlebotomists were monitored for 20 working days, to guarantee the adoption of the correct new procedures for collection of diagnostic blood specimens. After this time frame the phlebotomists were evaluated to verify whether the new procedure for blood collection derived from CLSI H03-A6 document was effective to improve the quality process by decrease in tourniquet application time. We compared the tourniquet application time and qualitative difference of phlebotomy procedures between laboratories before and after phlebotomy training.

Results:

The overall mean ± SD tourniquet application time before and after this intervention were 118 ± 1 s and 30 ± 1 s respectively. Minor modifications in procedure for blood collection were able to reduce significantly the tourniquet application time (−88 s, P < 0.001).

Conclusions:

The minor modifications in procedure for collection of diagnostic blood specimens by venipuncture from CLSI H03-A6 document were able to reduce the tourniquet application time. Now the proposed new procedure for collection of diagnostic blood specimens by venipuncture could be considered usefulness and should be put into practice by all quality laboratory managers and/or phlebotomy coordinators to avoid preanalytical errors regard venous stasis and guarantee patient safety.

Controlling sources of preanalytical variability in doping samples: challenges and solutions

The use of illicit substances and methods contravenes the ethics of sports and may be associated with side effects. Antidoping testing is an essential tool for preventing or limiting the consequences of cheating in sports. As for conventional laboratory testing, major emphasis has been placed on analytical quality, overlooking the inherent risks that may arise from analysis of unsuitable doping samples. The adherence to scrupulous criteria for collection, handling, transportation and storage of samples, especially blood and urine samples, is essential. The leading preanalytical variables that influence doping sample quality include biological variability, sample collection, venous stasis, spurious hemolysis and presence of other interfering substances, sample manipulation and degradation, and inappropriate conditions for transportation and storage. This article provides a personal overview about the current challenges in preanalytical management of doping samples, as well as potential solutions for preventing the negative impact of preanalytical variables on sample quality and test results.

Impact of the phlebotomy training based on CLSI/NCCLS H03-a6 - procedures for the collection of diagnostic blood specimens by venipuncture

Introduction:

The activities involving phlebotomy, a critical task for obtaining diagnostic blood samples, are poorly studied as regards the major sources of errors and the procedures related to laboratory quality control. The aim of this study was to verify the compliance with CLSI documents of clinical laboratories from South America and to assess whether teaching phlebotomists to follow the exact procedure for blood collection by venipuncture from CLSI/NCCLS H03-A6 - Procedures for the Collection of Diagnostic Blood Specimens by Venipuncture might improve the quality of the process.

Materials and methods:

A survey was sent by mail to 3674 laboratories from South America to verify the use of CLSI documents. Thirty skilled phlebotomists were trained with the CLSI H03-A6 document to perform venipuncture procedures for a period of 20 consecutive working days. The overall performances of the phlebotomists were further compared before and after the training program.

Results:

2622 from 2781 laboratories that did answer our survey used CLSI documents to standardize their procedures and process. The phlebotomists’ training for 20 days before our evaluation completely eliminated non-conformity procedures for: i) incorrect friction of the forearm, during the cleaning of the venipuncture site to ease vein location; ii) incorrect sequence of vacuum tubes collection; and iii) inadequate mixing of the blood in primary vacuum tubes containing anticoagulants or clot activators. Unfortunately the CLSI H03-A6 document does not caution against both unsuitable tourniquet application time (i.e., for more than one minute) and inappropriate request to clench the fist repeatedly. These inadequate procedures were observed for all phlebotomists.

Conclusion:

We showed that strict observance of the CLSI H03-A6 document can remarkably improve quality, although the various steps for collecting diagnostic blood specimens are not a gold standard, since they may still permit errors. Tourniquet application time and forearm clench should be verified by all quality laboratory managers in the services. Moreover, the procedure for collecting blood specimens should be revised to eliminate this source of laboratory variability and safeguard the quality.

Influence of mechanical trauma of blood and hemolysis on PFA-100 testing

Although the appropriate quality of samples is essential for platelet function testing, information is lacking on interference from mechanical trauma of blood and hemolysis on PFA-100 analyzer. Citrated blood collected from nine healthy volunteers was divided into three aliquots. The first aliquot ('A') was processed without further manipulation, whereas the second and third were subjected to mechanical trauma by two ('aliquot B') or four passages ('aliquot C') through a very fine needle (30 gauge) to produce hemolysis and cell trauma mimicking poor sample collection. Samples were tested on PFA-100 and Advia 2120, and plasma then separated and tested for lactate dehydrogenase (LDH) and hemolysis index. Negligible hemolysis was present in aliquot A (hemolysis index 0.2 ± 0.1, cell-free hemoglobin 0-0.5 g/l), whereas an increasing amount was present in aliquots B (hemolysis index of 13.1 ± 1.8, cell-free hemoglobin 6.0-6.5 g/l) and C (hemolysis index 24.0 ± 1.1, cell-free hemoglobin 11.5-12.0 g/l). Increases in LDH, and concomitant reductions in platelet and red blood cell counts were observed in aliquots B and C. In hemolyzed aliquots B, four out of nine samples yielded 'flow obstruction' with both PFA-100 agonist cartridges, whereas the closure times were dramatically prolonged in the remaining five samples. In hemolyzed aliquots C, flow obstruction was recorded in six of nine samples for collagen and ADP and all samples for collagen and epinephrine, whereas closure times of collagen and ADP in the remaining three samples were dramatically prolonged. Mechanical trauma of blood causing hemolysis makes PFA-100 testing unreliable. When flow obstructions are observed, the potential presence of hemolysis should be investigated.

Biological variation of INR in stable patients on long-term anticoagulation with warfarin

Within-individual biological variation of INR (CV(B)) was assessed in 245 selected stable warfarin-treated patients monitored by three thrombosis centers. Selection criteria were: treatment period of six months or longer before the observation period; at least six consecutive INRs within the therapeutic range of 2.0 - 3.0; interval between consecutive INR measurements of two weeks or longer; no change in warfarin dose; no changes in the patient's circumstances which may influence the INR, such as intercurrent diseases, invasive procedures, starting or stopping drugs interacting with warfarin. The minimum, maximum and mean within-individual coefficient of variation CV(B) of the INR measurements in the 245 selected patients were 0.4%, 14.5%, and 9.0%, respectively Analytical performance goals for the INR measurement (imprecision) could be derived from the mean CV(B). For a therapeutic range of 2.0 - 3.0 with warfarin, the desirable and optimum imprecision of INR determination is <4.5% CV and <2.25% CV, respectively. The biological variation and analytical performance goals have been derived using classic laboratory methods but should be applicable to point-of-care testing as well.

Transillumination: a new tool to eliminate the impact of venous stasis during the procedure for the collection of diagnostic blood specimens for routine haematological testing

INTRODUCTION

The collection of diagnostic blood specimens for routine haematological testing (RHT) is traditionally performed with tourniquet. However, the transillumination devices based on cold near-infrared LEDs have been formerly proposed as a valuable tool for identifying reliable venous accesses, especially in patients with difficult or small veins, such as children. This study was aimed to evaluate whether a transillumination device can advantageously replace the use of the tourniquet during the procedure for collection of blood specimens for RHT and thereby eliminating the discomfort and risk of spurious results caused by excessive or prolonged venous stasis.

METHODS

Two hundred and fifty volunteers were divided into five groups (G1, G2, G3, G4 and G5) to compare the results of RHT between blood sample collected with transilluminator device (left arm) and with tourniquet application (right arm) for 30 s(G1), 60 s(G2), 90 s(G3), 120 s(G4) and 180 s(G5).

RESULTS

No significant increases were observed in any of the haematological parameters tested in G1 when compared with blood collected by the transilluminator device. From G2 to G5, significant increases were observed for the platelet count, red blood cell count, haemoglobin, haematocrit, white blood cell count, neutrophils, monocytes and eosinophils. From G3-G5, further increases were observed for lymphocytes. Clinically significant variations were, however, observed for basophils in G2; red blood cell count, haemoglobin, haematocrit and basophils in G3 and eosinophils in G3 only.

CONCLUSION

As such, considering that inappropriate use of the tourniquet is commonplace, we conclude that transillumination devices can represent a suitable tool to eliminate the venous stasis and to improve the quality of phlebotomy procedures.

Blood sample collection and patient identification demand improvement: a questionnaire study of preanalytical practices in hospital wards and laboratories

Scand J Caring Sci; 2010; 24; 581-591 
 Blood sample collection and patient identification demand improvement: a questionnaire study of preanalytical practices in hospital wards and laboratories

BACKGROUND

  Most errors in venous blood testing result from human mistakes occurring before the sample reach the laboratory.

AIMS

  To survey venous blood sampling (VBS) practices in hospital wards and to compare practices with hospital laboratories.

METHODS

  Staff in two hospitals (all wards) and two hospital laboratories (314 respondents, response rate 94%), completed a questionnaire addressing issues relevant to the collection of venous blood samples for clinical chemistry testing.

RESULTS

  The findings suggest that instructions for patient identification and the collection of venous blood samples were not always followed. For example, 79% of the respondents reported the undesirable practice (UDP) of not always using wristbands for patient identification. Similarly, 87% of the respondents noted the UDP of removing venous stasis after the sampling is finished. Compared with the ward staff, a significantly higher proportion of the laboratory staff reported desirable practices regarding the collection of venous blood samples. Neither education nor the existence of established sampling routines was clearly associated with VBS practices among the ward staff.

CONCLUSIONS

  The results of this study, the first of its kind, suggest that a clinically important risk of error is associated with VBS in the surveyed wards. Most important is the risk of misidentification of patients. Quality improvement of blood sample collection is clearly needed, particularly in hospital wards.

Shortened activated partial thromboplastin time: causes and management

Throughout the long history of the hemostasis laboratory, and as an evaluation of the coagulation cascade, the results of the activated partial thromboplastin time (APTT) have primarily been considered as an index of loss-of-function and rarely as an index of gain-of-function. Nevertheless, there are now several clinical and technical reasons that no longer allow us to simply ignore or overlook shortened APTTs in laboratory practice. It has long been suspected that the leading cause of shortened APTTs are related to preanalytical problems, in which case it would be inappropriate for a laboratory to issue such a test result, which would expectedly not adequately mirror the patient's true condition. Should such artifactual results be reliably ruled out, that is by confirming short APTT values on subsequent samples, it would then be worth considering to troubleshoot potential causes, inasmuch as this phenomenon may reflect a variety of clinically meaningful conditions, including an increased risk of thromboembolic events, cancer, myocardial infarction, thyroid disorders, diabetes, and pregnancy. Although there are no univocal data supporting the origin of this singular phenomenon as yet, we strongly encourage the utility of postanalytical laboratory guidance, including a relevant short accompanying comment in the laboratory report linked to the APTT test result, for example, noting 'Short APTT-potentially reflective of in-vitro activation of blood coagulation due to difficult collection. If the value is systematically confirmed in subsequent samples, please contact the laboratory to help assess the cause'.

Laboratory reporting of hemostasis assays: the final post-analytical opportunity to reduce errors of clinical diagnosis in hemostasis?

The advent of modern instrumentation, with associated improvements in test performance and reliability, together with appropriate internal quality control (IQC) and external quality assurance (EQA) measures, has led to substantial reductions in analytical errors within hemostasis laboratories. Unfortunately, the reporting of incorrect or inappropriate test results still occurs, perhaps even as frequently as in the past. Many of these cases arise due to a variety of events largely outside the control of the laboratories performing the tests. These events are primarily preanalytical, related to sample collection and processing, but can also include post-analytical events related to the reporting and interpretation of test results. The current report provides an overview of these events, as well as guidance for prevention or minimization. In particular, we propose several strategies for the post-analytical reporting of hemostasis assays, and how this may provide the final opportunity to prevent serious clinical errors in diagnosis. This report should be of interest to both the laboratory scientists working in hemostasis and clinicians that request and attempt to interpret the test results. Laboratory scientists are ultimately responsible for these test results, and there is a duty to provide both accurate and precise results to enable clinicians to manage patients appropriately and to avoid the need to recollect and retest. Also, clinicians will not be in a position to best diagnose and manage their patient unless they gain an appreciation of these issues.

Patient hydration: a major source of laboratory uncertainty

Movement of body water from compartment to compartment during any time period is attributable to forces active within and upon each space. The result of these forces leads to transfer of water between intravascular and extravascular compartments, as well as shifts between extracellular and intracellular spaces. The importance of these shifts and of the associated mechanism was described by Ernest Starling in 1896 in very much the same manner as it is viewed today. The end result of fluid transfer and its physiological and laboratory consequences has not been fully appreciated. Despite awareness that fluid shifts can affect laboratory analytical results, little recent investigation has addressed the problem in the routine clinical laboratory. Thus, the potential for significant misinterpretation remains. For example, it is known that individual laboratory test values can vary widely, depending on many factors including the subject's posture during and immediately before phlebotomy, leading to significant changes in the interpretation of blood analyte values. Furthermore, a variety of ubiquitous environmental effects have additional impact on fluid distribution and thus on test values. In other words, patient hydration status is a major pre-analytical variable that needs to be addressed by the clinical laboratory. The need to adjust data for patient hydration status is especially important in the case of colloid analytes for which the dynamic range includes a narrow "gray zone" where hydration changes of a few percentage points can change the clinical implications. The crucial importance of this adjustment is underscored by the fact that neither the testing laboratory nor the clinician are aware of this unseen circumstance and are thus compelled to work with data that do not necessarily reflect the clinical situation.

Influence of the needle bore size on platelet count and routine coagulation testing

The phlebotomy technique, particularly the use of small-bore needles, may influence the reliability of coagulation testing and platelet count. Routine coagulation tests were assayed in blood specimens collected from 22 consecutive patients in three separate, sequential phlebotomies, using butterfly devices with different needle sizes. Test results of samples collected with 23 and 25 G needles were compared with those obtained with the currently recommended 21 G needle. Although both the prothrombin time and activated partial thromboplastin time displayed a trend towards lower values employing the smaller 23 and 25 G needles, results did not differ significantly from the reference 21 G needle specimen, with the exceptions of D-dimer (25 G versus 21 G needle, 186 +/- 70 versus 178 +/- 66/ml, P < 0.01) and platelet count (23 G versus 21 G needle, 246 +/- 55 versus 254 +/- 56 x 10(-3)/l, P < 0.01; 25 G versus 21 G needle, 240 +/- 55 versus 254 +/- 56 x 10(-3)/l, P < 0.01). None of the mean biases recorded for the parameters was clinically meaningful, nor did they exceed the current desirable analytical quality specifications for desirable bias. Results of the present investigation suggest that, when a proper technique is used and within certain limitations, butterfly devices with small-bore needles may be a reliable alternative to draw venous blood for platelet count and coagulation testing.

Quality and reliability of routine coagulation testing: can we trust that sample?

Poor standardization of preanalytic variables exerts a strong influence on the reliability of coagulation testing, consuming valuable health care resources and compromising patient outcome. Most uncertainties emerge from patient misidentification and the procedures for specimen collection and handling. Location of unsuitable venous access or problematic phlebotomies may produce spurious activation of the hemostatic system and hemolytic specimens. Prolonged venous stasis is associated with hemoconcentration and spurious variations of most coagulation assays. Additional pitfalls can be introduced by inappropriate phlebotomy tools and small-gauge needles. Inappropriate filling and mixing of the tube, unsuitable procedures for centrifugation and storage of the specimens are additional aspects that need accurate standardization. Besides traditional preanalytic variables affecting routine coagulation testing, thrombin-generation assays require specific criteria to be accurately fulfilled. These aspects include the type of specimen (platelet-poor plasma, platelet-rich plasma or whole blood), blood collection tubes, storage conditions and the presence of residual platelets. Compliance with new international quality assessment programs, which will also involve coagulation laboratories, encompasses the adoption of suitable strategies for reducing undue variability throughout the whole testing process. Such strategies would not entail extraordinary costs and are affordable with a structured outlay of existing resources, educational policies and compliance with reliable guidelines.

Preanalytical variability: the dark side of the moon in laboratory testing

Remarkable advances in instrument technology, automation and computer science have greatly simplified many aspects of previously tedious tasks in laboratory diagnostics, creating a greater volume of routine work, and significantly improving the quality of results of laboratory testing. Following the development and successful implementation of high-quality analytical standards, analytical errors are no longer the main factor influencing the reliability and clinical utilization of laboratory diagnostics. Therefore, additional sources of variation in the entire laboratory testing process should become the focus for further and necessary quality improvements. Errors occurring within the extra-analytical phases are still the prevailing source of concern. Accordingly, lack of standardized procedures for sample collection, including patient preparation, specimen acquisition, handling and storage, account for up to 93% of the errors currently encountered within the entire diagnostic process. The profound awareness that complete elimination of laboratory testing errors is unrealistic, especially those relating to extra-analytical phases that are harder to control, highlights the importance of good laboratory practice and compliance with the new accreditation standards, which encompass the adoption of suitable strategies for error prevention, tracking and reduction, including process redesign, the use of extra-analytical specifications and improved communication among caregivers.