Potential preanalytical and analytical vulnerabilities in the laboratory diagnosis of coronavirus disease 2019 (COVID-19)

A novel zoonotic coronavirus outbreak is spreading all over the world. This pandemic disease has now been defined as novel coronavirus disease 2019 (COVID-19), and is sustained by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As the current gold standard for the etiological diagnosis of SARS-CoV-2 infection is (real time) reverse transcription polymerase chain reaction (rRT-PCR) on respiratory tract specimens, the diagnostic accuracy of this technique shall be considered a foremost prerequisite. Overall, potential RT-PCR vulnerabilities include general preanalytical issues such as identification problems, inadequate procedures for collection, handling, transport and storage of the swabs, collection of inappropriate or inadequate material (for quality or volume), presence of interfering substances, manual errors, as well as specific aspects such as sample contamination and testing patients receiving antiretroviral therapy. Some analytical problems may also contribute to jeopardize the diagnostic accuracy, including testing outside the diagnostic window, active viral recombination, use of inadequately validated assays, insufficient harmonization, instrument malfunctioning, along with other specific technical issues. Some practical indications can hence be identified for minimizing the risk of diagnostic errors, encompassing the improvement of diagnostic accuracy by combining clinical evidence with results of chest computed tomography (CT) and RT-PCR, interpretation of RT-PCR results according to epidemiologic, clinical and radiological factors, recollection and testing of upper (or lower) respiratory specimens in patients with negative RT-PCR test results and high suspicion or probability of infection, dissemination of clear instructions for specimen (especially swab) collection, management and storage, together with refinement of molecular target(s) and thorough compliance with analytical procedures, including quality assurance

Survey on reporting of epithelial cells in urine sediment as part of external quality assessment programs in Brazilian laboratories

Epithelial cells (ECs) are structures regularly observed during urine microscopy analysis. The correct identification of EC subtypes can be useful since renal tubular epithelial cells (RTECs) are clinically relevant. We investigate the urinary ECs report and the judgement of its clinical importance by Brazilian laboratories. A survey with four questions was made available to participants of the Urinalysis External Quality Assessment Program (EQAP) from Controllab. Laboratories composed 3 groups: (1) differentiating ECs subtypes: “squamous”, “transitional” and “RTECs”; (2) differentiating ECs subtypes: “squamous” or “non-squamous” cells; (3) without ECs subtype identification. Participants did not necessarily answer to all questions and the answers were evaluated both within the same laboratory’s category and within different categories of laboratories. A total of 1336 (94%) laboratories answered the survey; Group 1, 119/140 (85%) reported that ECs differentiation is important to the physician and 62% want to be evaluated by EQAP, while in Group 3, 455/1110 (41%) reported it is useful to them, however only 25% want be evaluated by EQAP. Group 2 laboratories 37/51 (73%) reported that the information is important, but only 13/52 (25%) are interested in an EQAP with differentiation of the 3 ECs subtypes. Most of the laboratories do not differentiate ECs in the three subtypes, despite the clinical importance of RTECs. Education of laboratory staff about the clinical significance of urinary particles should be considered a key priority

The impact of venepuncture training on the reduction of pre?analytical blood sample haemolysis rates: A systematic review

BackgroundVenepuncture involves the introduction of a needle into a vein to collect a representative blood sample for laboratory testing. In the pre‐analytical phase, haemolysis (the rupturing of erythrocytes and release of their contents into the extracellular compartment) has safety, quality and cost implications. Training in correct venepuncture practice has the potential to reduce in vitro haemolysis rates, but the evidence for this notion has yet to be synthesised.DesignSystematic review (PRISMA Checklist).MethodsPublished studies on the effectiveness of venepuncture training on haemolysis rates were searched in relevant databases. The McMaster critical appraisal tool was used to assess methodological quality. The GRADE tool was used to evaluate the body of evidence in relation to the research questions. Implementation fidelity was also scrutinised in each study.ResultsEight out of 437 retrieved studies met the inclusion criteria. None were randomised controlled trials (RCT). Between‐study heterogeneity in design, intervention characteristics and the biochemical threshold for haemolysis precluded a meta‐analysis. Post‐training reductions in haemolysis rates of between 0.4%–19.8% were reported in four of the studies, which developed their intervention according to a clear evidence base and included mentoring in the intervention. Rises in haemolysis rates of between 1.3%–1.9% were reported in two studies, while the intervention effect was inconsistent within two other studies.ConclusionThere are no RCTS on the effectiveness of venepuncture training for reducing haemolysis rates, and findings from the existing uncontrolled studies are unclear. For a more robust evidence base, we recommend more RCTs with standardisation of haemolysis thresholds and training‐related factors.Relevance to clinical practiceWhile venepuncture training is an important factor influencing quality of blood sample in clinical practice, more robust evidence is needed to make specific recommendations about training content for reduction of haemolysis rates. Standardisation of haemolysis thresholds would also enable future meta‐analyses

A study of wall tie force distribution in veneer wall systems (stage 1)

The performance of both cavity and veneer wall systems is critically dependant on the effective performance of the ties which connect the outer and inner leaves. In veneer construction the ties are the principal means of support of the external masonry leaf as they transfer the veneer loads to the structural back-up frame. In cavity construction, the ties allow the sharing of load between the two masonry leaves, with the tie forces being influenced by the relative stiffness of the leaves and the nature of the support for each leaf. In recent years there have been attempts to model this behaviour analytically with varying degrees of sophistication. These studies have shown that the distribution of forces in the ties is dependant on a range of factors, with the tie force certainly not just being a function of the tributary loading area for the tie. The Masonry Research Group at the University of Newcastle is involved in an on-going study of wall tie behaviour with a view to developing more realistic wall tie design rules. Some results on the behaviour of ties in cavity walls have been presented previously. This paper reports a study on typical Australian brick veneer walling systems which has concentrated on developing techniques to accurately monitor individual tie forces in veneer walls subjected to lateral loads. A convenient method for measuring individual tie forces is presented, together with confirmation that tie force redistribution occurs in veneer systems once ties reach their individual capacity

Cyclic in-plane shear behaviour of unreinforced masonry panels retrofitted with fibre reinforced polymer strips

An experimental study was conducted to assess the effect on strength and ductility of retrofitting unreinforced masonry (URM) shear panels with near surface mounted (NSM) fibre reinforced polymer (FRP) strips. A total of six wall panels, 1200mm x 1200mm, were subjected to vertical precompression combined with increasing reversing cycles of in-plane lateral displacement. The panels were tested first as URM, retrofitted with NSM FRP strips and then retested. The URM testing was conducted as part of a previous research study to investigate the effects of a damp proof course (DPC) layer incorporated near the base of the panels. The six panels failed in compression, with crushing at the corners and near-vertical cracking throughout the panels in the URM tests. For the current study, the panels were retrofitted using three different arrangements of FRP strip reinforcement and then retested using the same apparatus but with base sliding at the DPC level prevented. The tests were used to determine the effect on strength, displacement capacity and ductility achieved by FRP retrofitting the damaged URM panels compared to the original undamaged panels. The broader aim of the research is to identify techniques for improving the seismic performance of existing URM walls under in-plane shear loading

Static cyclic in-plane shear response of damaged masonry walls retrofitted with NSM FRP strips - An experimental evaluation

An experimental study was conducted to assess the effect on strength and ductility of retrofitting unreinforced masonry (URM) shear panels with near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) strips. A total of sixteen wall panels, 1200 mm × 1200 mm, were subjected to vertical pre-compression combined with increasing reversing cycles of in-plane lateral displacement. All wall panels were previously tested (prior to retrofitting) under compression and cyclic shear using three different pre-compression levels resulting in various levels of damage. The damaged walls were repaired, retrofitted with NSM FRP strips and retested under pre-compression stress levels of 2.8 MPa, 2 MPa and 1.4 MPa. The retrofitted walls displayed higher displacement capacities compared with URM walls highlighting the effectiveness of retrofitting URM walls under earthquake loading. The ultimate loads were not enhanced due to retrofitting under higher pre-compression levels. However the presence of the reinforcement did restore the ultimate loads to those observed for the original undamaged URM state. This meant that overall, the reinforcement was effective in increasing the energy dissipation capacity of the walls compared to URM. The improvements in the behaviour of the URM walls due to retrofitting were generally similar, irrespective of the amount of damage the URM walls experienced prior to retrofitting. The paper discusses the effect on strength, displacement capacity, energy dissipation and ductility achieved by FRP retrofitting of the damaged (lightly and highly) URM panels compared to the undamaged URM panels under different pre-compression levels. The broader aim of the research is to identify techniques for improving the seismic performance of existing URM walls under in-plane shear loading