scholarly journals Intraoperative use of transcranial motor/sensory evoked potential monitoring in the clipping of intracranial aneurysms: evaluation of false-positive and false-negative cases

2019 ◽  
Vol 130 (3) ◽  
pp. 936-948 ◽  
Author(s):  
Jaewoo Chung ◽  
Wonhyoung Park ◽  
Seok Ho Hong ◽  
Jung Cheol Park ◽  
Jae Sung Ahn ◽  
...  
Keyword(s):  
Negative Predictive Value ◽  
Predictive Value ◽  
False Positive ◽  
Intracranial Aneurysms ◽  
Evoked Potential ◽  
False Negative ◽  
Motor Weakness ◽  
Negative Results ◽  
False Negative Results ◽  
Sensory Evoked

OBJECTIVESomatosensory and motor evoked potentials (SEPs and MEPs) are often used to prevent ischemic complications during aneurysm surgeries. However, surgeons often encounter cases with suspicious false-positive and false-negative results from intraoperative evoked potential (EP) monitoring, but the incidence and possible causes for these results are not well established. The aim of this study was to investigate the efficacy and reliability of EP monitoring in the microsurgical treatment of intracranial aneurysms by evaluating false-positive and false-negative cases.METHODSFrom January 2012 to April 2016, 1514 patients underwent surgery for unruptured intracranial aneurysms (UIAs) with EP monitoring at the authors’ institution. An EP amplitude decrease of 50% or greater compared with the baseline amplitude was defined as a significant EP change. Correlations between immediate postoperative motor weakness and EP monitoring results were retrospectively reviewed. The authors calculated the sensitivity, specificity, and positive and negative predictive values of intraoperative MEP monitoring, as well as the incidence of false-positive and false-negative results.RESULTSEighteen (1.19%) of the 1514 patients had a symptomatic infarction, and 4 (0.26%) had a symptomatic hemorrhage. A total of 15 patients showed motor weakness, with the weakness detected on the immediate postoperative motor function test in 10 of these cases. Fifteen false-positive cases (0.99%) and 8 false-negative cases (0.53%) were reported. Therefore, MEP during UIA surgery resulted in a sensitivity of 0.10, specificity of 0.94, positive predictive value of 0.01, and negative predictive value of 0.99.CONCLUSIONSIntraoperative EP monitoring has high specificity and negative predictive value. Both false-positive and false-negative findings were present. However, it is likely that a more meticulously designed protocol will make EP monitoring a better surrogate indicator of possible ischemic neurological deficits.

scholarly journals Evaluation of the Carba NP Test for Rapid Detection of Carbapenemase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

2013 ◽  
Vol 57 (9) ◽  
pp. 4578-4580 ◽  
Author(s):  
Nathalie Tijet ◽  
David Boyd ◽  
Samir N. Patel ◽  
Michael R. Mulvey ◽  
Roberto G. Melano
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Positive Predictive Value ◽  
Negative Predictive Value ◽  
Predictive Value ◽  
Rapid Detection ◽  
False Negative ◽  
Bacterial Extract ◽  
Content Type ◽  
Negative Results ◽  
False Negative Results

ABSTRACTThe Carba NP test was evaluated against a panel of 244 carbapenemase- and non-carbapenemase-producingEnterobacteriaceaeandPseudomonas aeruginosaisolates. We confirmed the 100% specificity and positive predictive value of the test, but the sensitivity and negative predictive value were 72.5% and 69.2%, respectively, and increased to 80% and 77.3%, respectively, using a more concentrated bacterial extract. False-negative results were associated with mucoid strains or linked to enzymes with low carbapenemase activity, particularly OXA-48-like, which has emerged globally in enterobacteria.

scholarly journals Combined CTP- IGF-1 Score: A New Score for Assessment of Disease Severity in HCV Related Liver Cirrhosis

2022 ◽  
Author(s):  
Elsayed Ghannam ◽  
Salah Rozaik ◽  
Ramy Hasan Agwa ◽  
Ahmed Marwan ◽  
Mervat El-Sayed Mashaly ◽  
...  
Keyword(s):  
Liver Cirrhosis ◽  
Negative Predictive Value ◽  
Predictive Value ◽  
False Negative ◽  
The Body ◽  
P Value ◽  
Study Group ◽  
Negative Results ◽  
False Negative Results ◽  
Ctp Score

Abstract Background: Liver is the largest endocrine organ in the body. It is a key organ in insulin mediated metabolism, growth hormone and insulin like growth factors (IGF) pathway. Liver cirrhosis is the end result of many chronic diseases including hepatitis C virus infection. Child-Turcotte-Pugh (CTP) score is the standard used in assessment of hepatic reserve but it has its drawbacks in the form of subjective variables, hepatic encephalopathy and ascites. The aim of this work is to assess IGF-1 in patients with liver cirrhosis, correlate it with CTP score and assess value of modified combined CTP-IGF-1 score. Patients and Methods: 170 patients with CLD (liver cirrhosis) and 72 healthy controls in the study groups were enrolled in the study. All patients were subjected to thorough history, clinical examination and laboratory assessment. IGF-1 was measured and all patients were evaluated using CTP and CTP-IGF-1 scores. Results: IGF1 showed highly significant low values in the study group in comparison to controls (42.15 ± 27.976 and 66.31 ± 33.084 ng/ml respectively, p <0.001). It showed also highly significant negative correlation to CTP score in the study group (p < 0.001) with progressive decrements with CTP score stage progression where IGF1 levels were 48.32 ± 28.611, 40.28 ± 25.869 and 18.80 ± 15.953 ng/ml (mean ± standard deviation) in relation to CTP score groups A, B and C respectively (p value < 0.001). The combined CTP-IGF-1 score in comparison to the classic CTP score showed improved area under curve (0.848 and 0.854), sensitivity (71.2% and 88%), negative predictive value (41.7% and 53.7%), false negative results (49 and 19) and accuracy (75.73% and 83.98%) but decreased specificity (97.22% and 61.1%), positive predictive value (99.2% and 91.5%) and higher false positive results (1 and 14) respectively. Conclusion: IGF-1 show progressive decrements with progression of liver cirrhosis and is negatively correlated with CTP score. Addition of IGF-1 to CTP score to formulate combined score improves the AUC, sensitivity, negative predictive value and the accuracy of CTP score and decreases the false negative results.

scholarly journals Study of ascitic fluid cytology in ovarian tumors

2017 ◽  
Vol 5 (12) ◽  
pp. 5227 ◽  
Author(s):  
Chandralekha Janagam ◽  
Bhagyalakshmi Atla
Keyword(s):  
Ascitic Fluid ◽  
Predictive Value ◽  
False Positive ◽  
False Negative ◽  
Ovarian Tumors ◽  
Peritoneal Cytology ◽  
Negative Results ◽  
Benign Ovarian Tumours ◽  
False Negative Results ◽  
Fluid Cytology

Background: The objectives of this study were to examine the validity of ascitic fluid cytology in the detection of pathological findings, to examine the percentage of false positive and false negative results in the cytology of ascitic fluid and to determine the validity of peritoneal cytology in relation to the histopathological type of the ovarian tumour.Methods: This retrospective study, over a period of 6 months, included 106 peritoneal cytology findings. The experimental group included 106 cytology findings obtained from patients who presented with an abdominal lump/mass with ascites and diagnosed with ovarian tumors clinically. They included 88 benign ovarian tumours (83%) and 18 malignant ovarian tumors (17%). Patients with other causes of ascites were excluded from the study.Results: The sensitivity of peritoneal cytology is 90%, specificity is 96.5%, positive predictive value is 85.7%, and negative predictive value is 97.6%. In 1.8% of patients, the peritoneal cytology showed false negative results, while in 2.8%, the results were false positive. False negative results were found in one case of teratoma with squamous cell carcinoma and one case of yolk sac tumor. False positive results were found in 2 cases of tuberculous-salpingo- oophoritis and one case of chronic salpingo-oophoritis due to reactive mesothelial proliferation, mistaken for adenocarcinoma.Conclusions: Peritoneal cytology of ascitic fluid is highly specific and sensitive for detection of ovarian malignancies, particularly in grade 3 and grade 4 disease, since most of the patients with ovarian malignancies present to us at advanced stage of the disease.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

Thyroid Screening for Early Discharged Infants

PEDIATRICS ◽  
1996 ◽  
Vol 98 (1) ◽  
pp. 41-44
Author(s):  
Judy G. Saslow ◽  
Ernest M. Post ◽  
Carol A. Southard
Keyword(s):  
New Jersey ◽  
Congenital Hypothyroidism ◽  
False Positive ◽  
False Negative ◽  
Negative Results ◽  
Thyroid Screening ◽  
False Negative Results ◽  
Positive Results

Objective. As neonatal discharge before 24 hours of life becomes commonplace, the rejection of congenital hypothyroidism (CH) screening specimens obtained too early has created the need for numerous additional tests. We sought to determine whether the specimens obtained before 24 hours could be used safely. Methods. During a 31-day period we measured thyrotropin in all thyroid-screening specimens that had been obtained before 24 hours. We also examined the early specimens from every infant diagnosed in New Jersey with CH during 1993 or 1994. Results. Among the 663 specimens, those obtained at or before 12 hours and those from infants with birth weights less than 2500 g had too many low thyroxine results to be useful. Among the 515 specimens obtained at more than 12 to 24 hours from newborns weighing 2500 g or more, 37 (7%) had low thyroxine levels and 12 (2.3%) had thyrotropin levels of 20 µIU/mL (mU/L) or higher. Four hundred seventy-one of the 515 infants had subsequent specimens obtained at more than 24 hours, and none of the results were abnormal. There was no child weighing more than or equal to 2500 g who was diagnosed with CH in 1993 and 1994 whose specimen obtained at 24 hours or less was normal. Conclusions. Accepting specimens obtained at more than 12 to 24 hours from infants weighing 2500 g or more would have resulted in more than the usual number of false-positive results but no false-negative results. This would have decreased the requests for additional specimens by more than 90%.

scholarly journals Interference of Asfotase Alfa in Immunoassays Employing Alkaline Phosphatase Technology

2019 ◽  
Vol 5 (2) ◽  
pp. 290-299
Author(s):  
Isabelle Danielle Piec ◽  
Beatrice Tompkins ◽  
William Duncan Fraser
Keyword(s):  
Alkaline Phosphatase ◽  
False Positive ◽  
Troponin I ◽  
Detection System ◽  
False Negative ◽  
Detection Systems ◽  
Asfotase Alfa ◽  
Negative Results ◽  
False Negative Results ◽  
Alternative Detection

Abstract Background Asfotase alfa (STRENSIQ®, Alexion Pharmaceuticals, Inc.) is the only approved treatment for patients with pediatric-onset hypophosphatasia, a disease caused by a mutation in the tissue-nonspecific alkaline phosphatase (TNSALP) gene. ALP is often used as signaling system in routine immunoassays. Because asfotase alfa contains the active site of the full ALP enzyme, it can catalyze the substrate as the antibody-conjugated ALP would within an assay. Therefore, its presence in a treated patient’s sample may generate false positive or false negative results. We investigated whether the presence of asfotase alfa within a sample induced interference in immunoassays that utilize ALP or alternative detection systems. Methods Asfotase alfa was added to samples at concentrations from 0.08–5 µg/mL and analysed on various immunoassays following manufacturer’s instructions. Results Asfotase alfa was detected in all ALP assays but ALKP1 (RayBiotech). We observed no changes in normetanephrine and noradrenaline (IBL) at any asfotase alfa concentration. However, asfotase alfa notably interfered in an oxytocin (ENZO) assay in nonextracted samples. Extraction using a C18 column eliminated the interference. No interference was observed on automated analyzers using alternative detection system (COBAS fT4 and TSH; Advia Centaur FSH, fT4; Architect LH; FSH). Immulite 2000 fT4, TSH, testosterone and hCG (ALP-based) showed no interference. However, the presence of asfotase alfa resulted in a dose-dependent increase of Troponin I signal. Conclusion The presence of asfotase alfa must be taken into consideration when analyzing blood samples in treated patients to avoid any risk of misinterpretation of false positive/negative results. It is essential that assays be tested for this possible interference.

Review of Inpatient Thrombophilia Testing at a Tertiary Care Center

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S147-S147
Author(s):  
Andrew Hall ◽  
Ortega Lopez ◽  
Amy Powers
Keyword(s):  
Liver Disease ◽  
False Positive ◽  
Care Center ◽  
Thrombotic Event ◽  
Tertiary Care ◽  
False Negative ◽  
Anticoagulation Therapy ◽  
Tertiary Care Center ◽  
Negative Results ◽  
False Negative Results

Abstract Introduction Testing for thrombophilic risk factors is common in patients with thrombosis. However, inpatient hereditary thrombophilia work-ups are prone to false-positive and false-negative results due to concurrent acute phase changes, protein consumption, anticoagulation therapy, and liver disease. A recent ASCP Choosing Wisely guideline recommends against measuring protein C (PC), protein S (PS), or antithrombin III (AT3) to diagnose a hereditary deficiency during an active clotting event. We aimed to review inpatient PC, PS, and AT3 activity assay ordering practices at a tertiary care center. The goal of this study was to determine appropriateness and identify areas for improvement in inpatient thrombophilia ordering practices. Methods A retrospective review of inpatients who underwent thrombophilia testing was performed. Inclusion criteria consisted of adult inpatients with PC, PS, and/or AT3 activity results. Patients for whom AT3 was ordered alone were excluded. The timeframe of testing relative to an acute thrombotic event, anticoagulation therapy, and liver disease was determined via electronic medical record review. Other conditions that can affect PC, PS, or AT3 levels were recorded if noted. Results Over 5 months, 50 inpatients underwent testing for PC, PS, and/or AT3. Testing was performed within 2 weeks of an acute thrombotic event in 92% of patients; 32% received anticoagulation therapy prior to testing and 16% had liver disease. Test results below the reference range were found in the following percentage of patients: 16% PC, 34% PS, and 16% AT3. In total, 23 of 50 (46%) patients had one or more abnormal results; all 23 had potential confounding conditions/drug. Conclusions Inpatient PC, PS, and AT3 testing was frequently performed in clinical settings, which may cause false-positive or false-negative results. This demonstrates the need for increased education and dialogue between the laboratory and clinicians to improve test utilization practices. Potential interventions are currently being analyzed.

False Positive and False Negative Radon Measurement Results Due to Uncertainties in Seasonal Correction Factors

1994 ◽  
Vol 56 (1-4) ◽  
pp. 291-292 ◽  
Author(s):  
K.D. Cliff ◽  
J.C.H. Miles ◽  
S.P. Naismith
Keyword(s):  
False Positive ◽  
False Negative ◽  
Geometric Standard Deviation ◽  
Correction Factors ◽  
Radon Measurement ◽  
Negative Results ◽  
False Negative Results ◽  
Initial Survey ◽  
The Uk ◽  
Radon Measurements

Abstract Data from the UK national survey of radon in 2300 homes has been re-analysed to determine the uncertainty in seasonal correction factors applied to measurements of less than l year. The required correction factor for each six-month result was calculated from the known annual average for the appropriate home. The seasonal correction factors derived for each month were found to be approximately log-normally distributed, with an average geometric standard deviation of 1.36. Following this initial survey, radon measurements have been made in more than 80,000 homes in southwest England to determine whether they are above the UK radon Action level of 200 Bq.m-3. The measurements were carried out over three months in each case using etched track detectors in two locations in each home, and the results were corrected for the average seasonal variation found in the original UK study of radon in homes. Because of the uncertainty in the seasonal correction factors, households with between 130 and 300 Bq.m-3 were advised to have a second three-month measurement in a different season before deciding whether or not to take remedial action. More than 7000 homes were remonitored for this purpose. The results are analysed to show the number of false positive and false negative results that would have been reported if advice had been based solely on the initial measurement. It is shown that the present scheme results in extremely small numbers of false positive and false negative results.

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