Three highly sensitive "bedside" serum and urine tests for pregnancy compared

1990 ◽  
Vol 36 (9) ◽  
pp. 1686-1688 ◽  
Author(s):  
H Christensen ◽  
H H Thyssen ◽  
O Schebye ◽  
A Berget
Keyword(s):  
Paired Comparison ◽  
False Negative ◽  
Diagnostic Sensitivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Negative Results ◽  
False Negative Results ◽  
Significant Difference ◽  
Comparison Of The Results ◽  
Urine And Serum

Abstract We examined three enzyme-linked immunosorbent assay (ELISA) kits for human choriogonadotropin (hCG) (pregnancy tests) for use with urine and serum samples: the Tandem Icon II hCG Urine and Tandem Icon II hCG Serum, the NovoClone Target hCG Test, and the Abbott TestPacks hCG-urine and hCG-serum. Paired comparison of the results from each kit indicated that the NovoClone Target assay showed significantly lower diagnostic sensitivity (P less than 0.05) than did the Tandem Icon II or Abbott TestPack, both for urine and for serum samples. None of the products demonstrated any significant difference (P greater than 0.05) in diagnostic specificity, but the NovoClone Target kit showed several serious false-negative results with both urine and serum. Paired testing of urine kits vs serum kits also showed no significant differences (P greater than 0.05) in diagnostic sensitivity or specificity. We found the Abbott kits to be the most convenient to use and to read.

scholarly journals Early Detection of Maedi-Visna (Ovine Progressive Pneumonia) Virus Seroconversion in Field Sheep Samples

2001 ◽  
Vol 13 (4) ◽  
pp. 301-307 ◽  
Author(s):  
R. Varea ◽  
E. Monleón ◽  
C. Pacheco ◽  
L. Luján ◽  
R. Bolea ◽  
...  
Keyword(s):  
Early Detection ◽  
False Negative ◽  
Field Conditions ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Negative Results ◽  
Visna Virus ◽  
False Negative Results ◽  
Ovine Progressive Pneumonia ◽  
Antibody Levels

The aim of this work was to investigate whether an enzyme-linked immunosorbent assay (ELISA) was useful for early detection of maedi-visna virus (MVV) infection in sheep under field conditions. An ELISA based on p25 recombinant protein and a gp46 synthetic peptide was used. Sequentially obtained serum samples ( n = 1,941) were studied for 4 years. ELISA results were compared with those of the agar gel immunodiffusion (AGID) test, and results of both tests were compared with a reference result established using consensus scores for at least 2 of 3 serologic techniques (AGID, ELISA, and western blotting, which was used to resolve result discrepancies between the other 2 techniques). A total of 247 discrepancies were observed between ELISA and AGID. Of these, 131 were due to an earlier detection of 120 sera by the ELISA and 11 sera by AGID. The remaining discrepancies (116) were due to the presence of false reactions in both tests. Fewer false-negative results were found by ELISA than with AGID (6 vs. 69 sera, respectively), whereas the number of false-positive results was virtually the same for ELISA and AGID (21 vs. 20, respectively). In relation to the reference result, ELISA sensitivity and specificity were 97.8% and 98.2%, respectively, whereas values for AGID were 76.3% and 98.3%, respectively. The agreement between ELISA and the reference result was higher than that between AGID and the reference result (κ value: 0.96 and 0.77, respectively). A variation in the ELISA signal (based on optical density) was observed during the study period, suggesting different antibody levels throughout the animal's life. The ELISA was useful for detecting MVV-infected sheep in field conditions and has potential for use in control and eradication programs.

Effect of Muscle Activation on the Gravity Stress View in Unstable Weber B Ankle Fractures

2020 ◽  
Vol 41 (11) ◽  
pp. 1342-1346
Author(s):  
Kimberly K. Broughton ◽  
Caroline Williams ◽  
Christopher P. Miller ◽  
Kristen Stupay ◽  
John Y. Kwon
Keyword(s):  
Muscle Activation ◽  
False Negative ◽  
Ankle Fractures ◽  
Published Data ◽  
Neutral Position ◽  
Distal Fibula ◽  
Level Of Evidence ◽  
Negative Results ◽  
False Negative Results ◽  
Significant Difference

Background: In the setting of apparently isolated distal fibula fractures, the gravity stress view (GSV) is a validated method to determine mortise stability. There is currently no published data evaluating whether dynamic muscle activation can reduce an unstable mortise. If patients with instability can overcome gravity, resultant images could yield false-negative results. The goal of this investigation was to determine if patient effort can influence medial clear space (MCS) measurements in proven unstable bimalleolar-equivalent ankle fractures. Methods: Patients presenting with Weber B fibula fractures were assessed for mortise stability using the GSV. If the GSV demonstrated instability based on MCS widening >4 mm, 3 additional views were performed: GSV with an assistant maintaining the ankle in a neutral position; GSV with the patient actively dorsiflexing to neutral; and GSV with the patient actively dorsiflexing and supinating the foot. Twenty-four consecutive patients met inclusion criteria, with a mean age of 48.7 (range, 22-85) years. Fifteen patients (62.5%) were female and 9 (37.5%) were male. The laterality was evenly divided. Results: The mean MCS was 5.8 ± 2.0 6.0 ± 2.6, and 6.2 ± 2.7 mm for the manual assist, active dorsiflexion, and active supination radiograph measurement groups, respectively ( P = .434). Only 5 of 24 subjects had any measurable decrease in their MCS with active supination, with a maximum change of 1.2 mm. The remainder of the patients had an increase in MCS ranging from 0.1 to 4.0 mm. Conclusion: There was no significant difference between measurement states indicating that muscle activation is unlikely to yield a false-negative result on GSV. Mortise instability, secondary to deep deltoid injury in the presence of gravity stress, is unlikely to be actively overcome by dynamic stabilizers, supporting the validity and specificity of the GSV. Level of Evidence: Level III, prospective study.

scholarly journals Can Patient Effort Influence Sensitivity & Specificity of the Gravity Stress View? Assessing the Potential for False Negative Results

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0014
Author(s):  
Kimberly K. Broughton ◽  
Christopher P. Miller ◽  
Caroline Williams ◽  
Kristen L. Stupay ◽  
John Y. Kwon
Keyword(s):  
Muscle Activation ◽  
Stress Test ◽  
False Negative ◽  
Ankle Fractures ◽  
Measurement Tool ◽  
Neutral Position ◽  
Distal Fibula ◽  
Negative Results ◽  
False Negative Results ◽  
Significant Difference

Category: Ankle; Trauma Introduction/Purpose: In the setting of apparently isolated distal fibula fractures, the radiographic gravity stress view (GSV) has been validated as a reliable method to determine mortise stability. Based on previous studies demonstrating that plantarflexion can increase the measured medial clear space (MCS), patients are often asked to actively hold their ankle in a neutral position. However, it has not been studied whether dynamic muscle activation in the form of attempted dorsiflexion and/or supination can reduce and realign an unstable mortise. If these efforts can overcome gravity, resultant images could lead to a false negative result and missed diagnosis of instability. The goal of the present investigation is to determine if active effort by the patient can influence MCS measurements in proven unstable bimalleolar-equivalent ankle fractures. Methods: Eighteen consecutive patients with apparently isolated distal fibula fractures (Weber-B type) identified on initial nonweightbearing radiographs were assessed for mortise stability with a standard, unassisted GSV. If the radiograph demonstrated MCS widening > 4 mm, 3 additional views were performed: GSV with an assistant manually maintaining the ankle in a neutral position; GSV with the patient actively dorsiflexing the ankle to the same neutral position; and GSV with the patient actively dorsiflexing and supinating the foot to the same neutral position. All radiographs were digitally obtained and measured using a DICOM measurement tool. The MCS was measured by the senior author (JYK) who was blinded to the nature of the ankle position. Statistical analysis of the data was then conducted. Results: Of the eighteen patients who met inclusion criteria, the mean age was 48.9 years (range: 22-85, SD=18.9). Twelve patients (66%) were female and six (33%) were male. The laterality was evenly split with nine patients presenting with a right ankle injury and nine left ankles. The data was non-parametric; therefore, a Friedman’s test was utilized for analysis between the different MCS measurements per patient. There was no statistically significant difference in the measured MCS in any of the three tested scenarios, χ2(2)=4.261, p=0.119. Only 5 of 18 subjects had any measurable decrease in their MCS when asked to supinate their foot. Of these 5, the maximum reduction was 1.21mm. The remainder of patients had an increase in MCS ranging from 0.1 to 4.0mm. Conclusion: This investigation supports the notion that the gravity stress test is unlikely to yield false negative results when patients attempt to actively maintain a neutral ankle position during imaging. There was a non-significant inverse trend indicating that dynamic effort may in fact further displace the mortise as indicated by an increased MCS in several study participants, rather than reduce it. Thus, one can conclude that despite voluntary effort, patients with bimalleolar-equivalent ankle fractures are unlikely able to overcome the effect of gravity on the unstable mortise.

scholarly journals False negative results in the Roche assay for HDL-cholesterol

2003 ◽  
Vol 40 (5) ◽  
pp. 572-575 ◽  
Author(s):  
Andries J Bakker ◽  
Appie Zijlstra ◽  
Marten P Leemhuis
Keyword(s):  
Cardiovascular Disease ◽  
Risk Evaluation ◽  
False Negative ◽  
Hdl Cholesterol ◽  
Daily Practice ◽  
Vascular Risk ◽  
Serum Samples ◽  
Negative Results ◽  
Risk Estimates ◽  
False Negative Results

Measurement of HDL-cholesterol is important in the risk evaluation of cardiovascular disease. Recently, we encountered a 61-year-old man with a negative result for HDL-cholesterol using the Roche assay. Further analysis revealed that this patient had a monoclonal Ig type IgM κ, with an electrophoresis-based concentration of 55.8 g/L, which apparently caused the negative result for HDL-cholesterol. Analysis of serum samples from other patients with monoclonal or polyclonal hypergammaglobulinaemia revealed that false negative results in the Roche assay for HDL-cholesterol may occur incidentally. Since negative results are detected easily in the laboratory, such patients do not pose a problem in daily practice. However, it is reasonable to suppose that false low results could also be caused by monoclonal as well as polyclonal Igs. Since such false low results remain undetected, vascular risk estimates consequently are altered and unnecessary treatment might be started.

scholarly journals Assessment of the IgA Immunoassay Diagnostic Potential of the Mycobacterium tuberculosis MT10.3-MPT64 Fusion Protein in Tuberculous Pleural Fluid

2010 ◽  
Vol 17 (12) ◽  
pp. 1963-1969 ◽  
Author(s):  
Leonardo Silva Araujo ◽  
Renata Maciel Moraes ◽  
Anete Trajman ◽  
Maria Helena Féres Saad
Keyword(s):  
Pleural Fluid ◽  
Histopathological Examination ◽  
False Negative ◽  
High Sensitivity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Negative Results ◽  
Diagnostic Potential ◽  
False Negative Results ◽  
Sds Page ◽  
Increased Sensitivity

ABSTRACT Pleural tuberculosis (PL-TB) remains difficult to diagnose. An enzyme-linked immunosorbent assay (ELISA) was developed based on a construction containing the fusion of the Rv3019c (MT10.3) and Rv1980c (MPT64) gene sequences, and its performance was evaluated in an area where TB is endemic. A total of 92 pleural fluid (PF) samples at serial dilutions of 1:50 to 1:800 were included in the ELISA IgA MT10.3-MPT64 evaluation: 70 from TB patients and 22 from patients with other pleurisies. Confirmation of the expression and subsequent purification of the protein was made by SDS-PAGE and Western blot assays, resulting in a 36-kDa protein. ELISA IgA MT10.3-MPT64 showed sensitivities of 61.4%, 58.6%, 62.9%, 67.1%, and 70% at each PF dilution, respectively. The cumulative results of all dilutions increased sensitivity to 81.4% without jeopardizing specificity. Similar results were also obtained at the combined dilutions of 1:50, 1:200, and 1:800 or 1:50 plus 1:800 dilutions (80%). The overall sensitivity of the reference test, i.e., histopathological examination, was 74%. But, via the ELISA IgA MT10.3-MPT64 test, sensitivity was high for specimens with a negative culture (23/27; 85.2%) or nonspecific histopathology (17/18; 94.4%). Our findings demonstrated the promising use of this test as an adjunct in PL-TB diagnoses, particularly in cases with lower bacterial loads and false-negative results in the reference tests, since the new test includes such important features as quick and easy application, high sensitivity and, perhaps most importantly, affordability, which is so crucial for its widespread use in developing countries.

scholarly journals Clinical Performance of Two SARS-CoV-2 Serologic Assays

2020 ◽  
Vol 66 (8) ◽  
pp. 1055-1062 ◽  
Author(s):  
Mei San Tang ◽  
Karl G Hock ◽  
Nicole M Logsdon ◽  
Jennifer E Hayes ◽  
Ann M Gronowski ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Clinical Performance ◽  
False Negative ◽  
Diagnostic Sensitivity ◽  
Diagnostic Specificity ◽  
Negative Results ◽  
False Negative Results ◽  
Recent Emergence ◽  
Sensitivity Specificity ◽  
Record Review

Abstract Background The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in a rapid proliferation of serologic assays. However, little is known about their clinical performance. Here, we compared two commercial SARS-CoV-2 IgG assays. Methods 103 specimens from 48 patients with PCR-confirmed SARS-CoV-2 infections and 153 control specimens were analyzed using SARS-CoV-2 serologic assays by Abbott and EUROIMMUN (EI). Duration from symptom onset was determined by medical record review. Diagnostic sensitivity, specificity, and concordance were calculated. Results The Abbott SARS-CoV-2 assay had a diagnostic specificity of 99.4% (95% CI; 96.41–99.98%), and sensitivity of 0.0% (95% CI; 0.00–26.47%) at <3 days post symptom onset, 30.0% (95% CI; 11.89–54.28) at 3–7d, 47.8% (95% CI; 26.82–69.41) at 8–13d and 93.8% (95% CI; 82.80–98.69) at ≥14d. Diagnostic specificity on the EI assay was 94.8% (95% CI; 89.96–97.72) if borderline results were considered positive and 96.7% (95% CI; 92.54–98.93) if borderline results were considered negative. The diagnostic sensitivity was 0.0% (95% CI; 0.00–26.47%) at <3d, 25.0% (95% CI; 8.66–49.10) at 3–7d, 56.5% (95% CI; 34.49–76.81) at 3–7d and 85.4% (95% CI; 72.24–93.93) at ≥14d if borderline results were considered positive. The qualitative concordance between the assays was 0.83 (95% CI; 0.75–0.91). Conclusion The Abbott SARS-CoV-2 assay had fewer false positive and false negative results than the EI assay. However, diagnostic sensitivity was poor in both assays during the first 14 days of symptoms.

scholarly journals Imaging-Cytology Correlation of Thyroid Nodules with Initially Benign Cytology

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Shin Hye Hwang ◽  
Ji Min Sung ◽  
Eun-Kyung Kim ◽  
Hee Jung Moon ◽  
Jin Young Kwak
Keyword(s):  
Thyroid Nodules ◽  
False Negative ◽  
Needle Aspiration ◽  
Malignancy Rate ◽  
Negative Results ◽  
False Negative Results ◽  
Significant Difference ◽  
Risk Of Malignancy ◽  
Us Findings

Objective. To determine the role of imaging-cytology correlation in reducing false negative results of fine-needle aspiration (FNA) at thyroid nodules.Methods. This retrospective study included 667 nodules 1 cm or larger in 649 patients diagnosed as benign at initial cytologic evaluation and that underwent follow-up ultrasound (US) or FNA following a radiologist’s opinion on concordance between imaging and cytologic results. We compared the risk of malignancy of nodules classified into subgroups according to the initial US features and imaging-cytology correlation.Results. Among included nodules, 11 nodules were proven to be malignant (1.6%) in follow-up FNA or surgery. The malignancy rate was higher in nodules with suspicious US features (11.4%) than in nodules without suspicious US features (0.5%,P<0.001). When a thyroid nodule had discordant US findings on image review after having benign FNA results, malignancy rate increased to 23.3%, significantly higher than that of nodules with suspicious US features (P<0.001). However, no significant difference was found in the risk of malignancy between the nodules without suspicious US features (0.5%) and imaging-cytology concordant nodules (0.6%,P=0.438).Conclusions. Repeat FNA can be effectively limited to patients with cytologically benign thyroid nodules showing discordance in imaging-cytology correlation after initial biopsy, which reduces unnecessary repeat aspirations.

scholarly journals Heat inactivation of serum interferes with the immunoanalysis of antibodies to SARS-CoV-2

2020 ◽  
Author(s):  
Xiumei Hu ◽  
Taixue An ◽  
Bo Situ ◽  
Yuhai Hu ◽  
Zihao Ou ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
False Negative ◽  
Average Level ◽  
Heat Inactivation ◽  
Serum Antibodies ◽  
Serum Samples ◽  
Negative Results ◽  
False Negative Results ◽  
Before And After ◽  
Quantitative Fluorescence

AbstractThe detection of serum antibodies to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is emerging as a new tool for the coronavirus disease-2019 (COVID-19) diagnosis. Since many coronaviruses are sensitive to heat, heating inactivation of samples at 56 °C prior to testing is considered a possible method to reduce the risk of transmission, but the effect of heating on the measurement of SARS-CoV-2 antibodies is still unclear. By comparing the levels of SARS-CoV-2 antibodies before and after heat inactivation of serum at 56 °C for 30 minutes using a quantitative fluorescence immunochromatographic assay, we shown that heat inactivation significantly interferes with the levels of antibodies to SARS-CoV-2. The IgM levels of all the 34 serum samples (100%) from COVID-19 patients decreased by an average level of 53.56%. The IgG levels were decreased in 22 of 34 samples (64.71%) by an average level of 49.54%. Similar changes can also be observed in the non-COVID-19 diseases group (n=9). Of note, 44.12% of the detected IgM levels were dropped below the cut-off value after heating, suggesting heat inactivation can lead to false-negative results of these samples. Our results indicate that heat inactivation of serum at 56 °C for 30 minutes interferes with the immunoanalysis of antibodies to SARS-CoV-2. Heat inactivation prior to immunoanalysis is not recommended and the possibility of false-negative results should be considered if the sample was pre-inactivated by heating.

Enzyme-linked immunosorbent assay to diagnose human leptospirosis: a meta-analysis of the published literature

2012 ◽  
Vol 141 (1) ◽  
pp. 22-32 ◽  
Author(s):  
M. L. SIGNORINI ◽  
J. LOTTERSBERGER ◽  
H. D. TARABLA ◽  
N. B. VANASCO
Keyword(s):  
Direct Method ◽  
Meta Analysis ◽  
False Negative ◽  
Area Under The Curve ◽  
Disease Stage ◽  
Enzyme Linked Immunosorbent Assay ◽  
Stage Of Disease ◽  
Negative Results ◽  
Igm Elisa ◽  
False Negative Results

SUMMARYWe report an evaluation of the accuracy of ELISA for the detection ofLeptospira-specific antibodies in humans. Eighty-eight studies published in 35 articles met all inclusion criteria and were submitted to meta-analysis. Pooled sensitivity and specificity were 0·779 (95% CI 0·770–0·789) and 0·913 (95% CI 0·908–0·917), respectively, and the area under the curve was 0·964. Heterogeneity across studies was statistically significant, but none of the sources of heterogeneity (disease stage, antigen used, antibody detected) could fully explain this finding. Although the convalescent stage of disease was significantly associated with higher diagnostic accuracy, IgM ELISA was the best choice, regardless of the stage of disease. Negative ELISAs (IgG or IgM) applied in the acute phase do not rule out leptospirosis due to the possibility of false-negative results. In this case it is advisable to request a second blood sample or to apply a direct method for leptospiral DNA.

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