Coagulation Specimens Research Articles

The impact of laboratory staff training workshops on coagulation specimen rejection rates.

BackgroundPre-analytical variables can have a significant adverse impact on the quality and credibility of coagulation test results. Therefore, correct and consistent identification of pre-analytical variables that compromise coagulation specimen quality is of paramount importance. Lack of standardization and heterogeneity among laboratory staff when assessing coagulation specimens can lead to inconsistent identification of these variables. Failure to recognize such pre-analytical variables results in the analysis of poor quality specimens and the authorization of spurious test results.ObjectivesTo determine the impact of a laboratory staff training workshop on coagulation specimen rejection rates and to ascertain the level of knowledge of laboratory personnel concerning coagulation specimen rejection criteria before and after the workshop.MethodsA retrospective three-month audit was performed with rejection data of incorrect blood to additive ratio, clotted, aged and haemolysed specimens collected. Training workshops and evaluation sessions were subsequently presented. A revised standard operating procedure delineating coagulation specimen rejection criteria was implemented and a repeat three-month audit was conducted.ResultsIn total, 13 162 coagulation specimens were received during the initial audit with 1 104 specimens (8.39%) rejected. Following the workshops, the rejection rate increased by 3.49% to 11.88% with 12 743 coagulation specimens received and 1 514 specimens rejected. Evaluation sessions performed before and after the workshops revealed that 95.2% of attendees attained improved knowledge.ConclusionThis study demonstrated the pivotal importance of regular laboratory staff training. The increase in specimen rejection following the workshops signifies their success in educating laboratory personnel regarding the correct identification of pre-analytical variables. Since most pre-analytical variables occur outside the laboratory, educational workshops need to be extended to non-laboratory personnel responsible for specimen collection and transport.

Interferences between Clot in the Erythrocyte Sediment and Hemostasis Exploration.

The selection and rejection of non-conforming coagulation specimens is essential in safeguarding quality management in hemostasis laboratories that provide routine testing for bleeding and thrombotic disorders. In order to increase quality, it is important to reduce pre-analytical errors that generally account for 60 - 70% of total laboratory failure. The accidental presence of clots in vitro, in the pre-analytical phase of the coagulation, is a reason for coagulation specimen rejection, given that the reliability of test results can be adversely compromised. This study aimed to ascertain the effect of clots identified in the post-analytical phase within the blood sample sediments upon standard laboratory tests such as PT (prothrombin time) and APTT (activated partial thromboplastin time). From a total of 24,670 coagulation specimens gathered and prospectively collected and analyzed at the Haematology Laboratory of the ˮSf. Spiridonˮ Emergency County Hospital Iasi, Romania, during four months, 671 were identified with clot. Of the coagulated samples, 153 (22.80%) were considered for this study, including those specimens pinpointed with sediment clot through a post-analytical new reverification procedure. The comparative study of the PT and APTT results obtained based on the samples identified with sediment clots in relation to the actual results recorded after the repetition of the sampling, pointed out 43.93% false results for PT1 test, with a significant difference between the variances of the values at the two evaluated moments (t = 2.961, p = 0.0037). The pattern was congruent in the case of the APTT test as well, exhibiting 69.04% false results, for which the variances of values at the two evaluated moments displayed significant differences (t = 2.208, p = 0.0306). In both of the cases significantly lower mean values were noted in the second determination of PT (PT1: 33.1 ± 39.6 vs. PT2: 25.8 ± 30.5) and APTT (APTT1: 42.8 ± 42.7 vs. APTT2: 38.1 ± 26.1. Results are important as they highlight the actual interference between the clot in the erythrocyte sediment and the evaluation of the patient's hemostasis. Our results confirm that the presence of clots in the erythrocyte sediment, with no identification prior to centrifugation, significantly affect the PT and APTT analysis, their accurate results being critical for the proper diagnosis and monitoring of anticoagulant therapy.

Thrombin generation estimates the anticoagulation effect of direct oral anticoagulants with significant interindividual variability observed.

: Direct oral anticoagulants (DOACs) are increasingly being used, primarily due to their drug stability and patient convenience. Although these drugs have been evaluated to be well tolerated in numerous clinical trials, their impact on in-vivo anticoagulation effect, variability and therapeutic drug level remains unknown. Hence, we aim to study the effect and variability of DOACs on thrombin generation via the calibrated automated thrombogram. Anonymized coagulation specimens from outpatients on warfarin were collected. Pooled normal plasma samples were spiked with increasing concentrations of dabigatran, rivaroxaban and apixaban. Similarly, plasma samples with normal coagulation profiles were spiked with two concentrations each of dabigatran, rivaroxaban and apixaban. Thrombin generation via calibrated automated thrombogram was run using the above samples and compared with a dataset of normal controls. Increasing international normalized ratio was associated with a reduction of endogenous thrombin potential (ETP) and thrombin peak and increasing lag time. Factor Xa inhibitors produced a flattened thrombin generation curve with a reduction of thrombin peak and relative preservation of ETP. Direct thrombin inhibitors produced a reduction of both ETP and thrombin peak and increasing lag time. Seventy-one citrated plasma samples (26 dabigatran, 21 rivaroxaban and 24 apixaban) were evaluated. The two concentrations produced a reduction of thrombin generation parameters with significant interindividual variability compared with neat plasma of 35-93, 13-31 and 18-71% and for dabigatran, rivaroxaban and apixaban, respectively. Thrombin generation can measure the anticoagulation effect of commonly used DOACs, with each drug having a unique thrombin generation profile. The variability noted using the same concentration suggests significant interindividual pharmacodynamic differences, which maybe relevant with respect to efficacy as well as bleeding side effects. Further delineation of the modifiers of interindividual differences is required in the in-vivo setting.

Integrity of Uncapped Routine Coagulation Specimens Processed in an Automated Integrated Laboratory.

The validity of laboratory results depends on pre-analytical variables not detected by conventional quality control. Recommendations are for post-centrifugation coagulation samples to remain capped with cappiercing primary tube analysis. Total laboratory automation integrates analytical platforms with potential incompatibilities necessitating changes including pre-analytical uncapping of samples. Samples analyzed for Prothrombin Time (PT), activated Partial Thromboplastin Time (aPTT), D-dimers, Antithrombin and Fibrinogen at baseline, and after 60 and 120 minutes were left at ambient temperature, either re-capped or uncapped, in order to simulate changes from baseline that could occur in uncapped samples on an automation track prior to analysis. Changes were compared to the maximal permissible bias. Sample uncapping for up to 120 minutes at ambient temperature post-centrifugation did not result in clinically significant changes in routine coagulation parameters. Routine coagulation parameters will not change significantly if the primary citrate tubes are uncapped after centrifugation prior to analysis.

English

To investigate wheather cancer patients during and following chemotherapy with short activated partial thromboplastin times (aPTTs) have increased thrombin generation and are at increased risk for thromboembolism, this prospective study was designed. Routine coagulation specimens of such patients were screened for the presence of short or normal aPTT for 5-month period, and, accordingly, 250 specimens were collected. Prothrombin fragment F1+2 (F1+2) was measured to evaluate thrombin activation, and a second aPTT was performed with a different reagent. Clinical history were obtained from medical records after conclusion of sample collection. 6 to12months later, patients were questioned on thromboembolic events during the previous 18 months by questionnaire. F1+2 and the incidence of venous thromboses were elevated significantly in the short aPTT group. Patients with acute bleeding had short aPTTs, but 36% of these also had thromboembolic events during the 18 months proximal to blood collection. These findings were confirmed with the second aPTT reagent. Patients with short aPTTs have increased thrombin generation and are at increased risk for thromboembolism, mainly venous thromboses, despite the fact that a short aPTT can occur in the acute setting of bleeding. INTRODUCTION: The prothrombin time (PT) and the activated partial thromboplastin time (aPTT) are routine coagulation tests used to assess the coagulation system in a clinical setting. Numerous factor deficiencies are known to prolong the respective screening test result and can be related to bleeding; (1) however, prolongation of the aPTT may be related to a hypercoagulable state if a lupus anticoagulant is present.(2) A clinically relevant decrease in the activity of clotting factors usually related to the prolongation of one of the respective routine screening test results. By analogy, shortened clotting times could, therefore, be the expression of a hypercoagulable state. Earlier studies have found some evidence that short aPTTs are related to a higher incidence of throm- boembolic disorders. (3, 4) These findings have been disputed, and there is some suggestion in the literature that short aPTTs occur during bleeding episodes. (5, 6) Nowadays, molecular markers of activation processes in the coagulation and fibrinolytic system have become widely available for use in the specialized clinical laboratory. Prothrombin fragment F1+2 is cleaved from prothrombin on activation by factor Xa in amounts equimolar to the thrombin generated. (7) Consequently, F1+2 levels have been shown to reliably measure the amount of prothrombin activation and, thus, thrombin generation. (8) The purposes of the present study were to evaluate the hypothesis that in cancer patients

An audit of coagulation specimens requiring direct human involvement at an academic laboratory : peer reviewed original article

Introduction A trend exists towards automation in laboratory testing, including coagulation investigations. Some coagulation specimens cannot be summarily tested in fully automated systems because of suboptimal, pre-analytical factors that would influence results, while others require additional preparation prior to testing. The aim of this audit was to determine the proportion of coagulation specimens requiring direct human involvement for screening and additional sample preparation, and to analyse contributing factors. Methods All specimens received for coagulation testing over a ten-month period were audited. Specimens requiring direct human involvement (screening for suboptimal, pre-analytical influences; double centrifugation) were recorded. Results Of 8 614 specimens, 1 091 (12.7%) fell into one or more of the following categories: under-filled (2.9%); clotted (1.7%); incorrect specimen tubes (1.5%); lipaemic (0.1%); icteric (0.5%); haemolysed (0.9%); haematocrit >0.55 L/L (0.02%); old (1.9%); unlabelled or incorrectly labelled (0.2%); lupus anticoagulant (4.0%); activated protein-C resistance (0.1%). In total, 353 (4.1%) specimens required double centrifugation and 829 (9.6%) required screening. Conclusion A substantial proportion of specimens required direct human involvement and would not have been suitable for coagulation testing in current fully automated systems.

Hemolysis of Coagulation Specimens: A Comparative Study of Intravenous Draw Methods

Hemolysis of blood samples creates significant delays in the treatment and disposition of patients in the emergency department. The purpose of this study was to compare the hemolysis rates of coagulation blood samples obtained during insertion of an intravenous (IV) catheter without (group 1) or with (group 2) extension tubing connected to the IV catheter hub. A secondary purpose of this study was to determine whether the investigators could predict whether a coagulation sample was hemolyzed based on visual observation during the specimen withdrawal process. A prospective, 2-group randomized comparative design was used to determine which method of blood collection for coagulation specimens provided the lowest hemolysis rate. This study was conducted in an urban level I emergency department averaging 58,000 visits per year. The sample consisted of 121 adult ED patients randomly assigned to 1 of the 2 groups. Data collectors were trained in the 2 methods of coagulation sample collection and followed a strict protocol. The clinical laboratory used a standardized color-coded scale to determine hemolysis. Pearson χ(2) analysis was used to test for differences between all nominal variables. The level of significance for all tests was P < .05. There was no significant difference in hemolysis rates between the groups by use of χ(2) analysis (P = .84). Nurses were significantly more likely to predict that a sample was hemolyzed when it was not and to think that it was not hemolyzed when in fact it was (P < .001). High hemolysis rates occurred equally when coagulation blood samples were drawn via a peripheral IV catheter either at the hub or through extension tubing. Emergency nurse investigators could not accurately predict by visualization whether a coagulation sample was hemolyzed at the time of blood withdrawal. Venipuncture as the preferred method of blood draw is an industry recommendation. This method has been shown in prior experimental studies to reduce hemolysis rates to less than 4%. Therefore, if hemolysis rates are a concern, one should consider obtaining blood whenever possible through a venipuncture rather than through an IV catheter. Replication studies are needed to determine whether the findings of this study can be generalized to the larger population.

Effect on Routine and Special Coagulation Testing Values of Citrate Anticoagulant Adjustment in Patients With High Hematocrit Values

Recommendations to adjust citrate concentration for blood coagulation specimens with high hematocrit values are based on indirect experimental studies and not direct studies of patient samples with high hematocrit values. We compared the effect of adjusted and non-adjusted citrate concentrations on coagulation test results in samples from 28 patients with high hematocrit values (55%-72% [0.55-0.72]). Prothrombin time (PT) and activated partial thromboplastin time (aPTT) results from nonadjusted and adjusted samples were statistically different and exponentially increased with increasing hematocrit values. Results for fibrinogen, factor VIII, and protein C activity were statistically different and increased linearly with increasing hematocrit values; however, the difference was not as clinically significant. The protein C antigen value increased with increasing hematocrit values but was not significant. The effects on PT and aPTT are due to a dilutional effect of plasma and an interference effect of the higher final citrate concentration on the clotting test result. For patients with high hematocrit values, citrate concentrations must be adjusted for accurate results.

Modular Robotic Workcell for Coagulation Analysis

Total laboratory automation (TLA) has been shown to increase laboratory efficiency and quality. However, modular automation is smaller, requires less initial capital, and requires less planning than TLA. We engineered and performed clinical trials on a modular robotic preanalytical workcell for coagulation analysis. Timing studies were used to quantify the efficiency of the manual processes and to identify areas in the processing of coagulation specimens where bottlenecks and long waiting periods were encountered. We then designed our modular robotic system to eliminate these bottlenecks. Our robotic modular workcell was engineered to allow a choice of specimen introduction manually, by conveyor, or by mobile robot. Additional timing studies were performed during clinical trials of the robotic system. Prior to automation, the time required for preanalytical processing time was 18-107 min; after automation, it was 45-50 min. Additional improvements in workcell efficiency could be realized when high quality, prelabeled specimens were introduced into the system. Compared with manual methods, modular automation provides more predictable variation in specimen processing.

Short activated partial thromboplastin times are related to increased thrombin generation and an increased risk for thromboembolism.

This prospective study was designed to investigate whether patients with short activated partial thromboplastin times (aPTTs) have increased thrombin generation and are at increased risk for thromboembolism. During a 4-month period, routine coagulation specimens were screened for the presence of a short or normal aPTT, and, accordingly, 250 specimens were collected. Prothrombin fragment F1 + 2 (F1 + 2) was measured to evaluate thrombin activation, and a second aPTT was performed with a different reagent. Diagnoses were obtained from medical records after conclusion of sample collection. Five to 9 months later, patients were questioned on thromboembolic events during the previous 18 months by questionnaire and telephone interview. F1 + 2 and the incidence of venous thromboses were elevated significantly in the short aPTT group. Unexpectedly, patients with acute bleeding had short aPTTs, but 36% of these also had thromboembolic events during the 18 months proximal to blood collection. These findings were confirmed with the second aPTT reagent. Patients with short aPTTs have increased thrombin generation and are at increased risk for thromboembolism, mainly venous thromboses, despite the fact that a short aPTT can occur in the acute setting of bleeding.