scholarly journals Intradermal Drug Testing following Anaphylactoid Reactions during Anaesthesia

1981 ◽  
Vol 9 (4) ◽  
pp. 381-386 ◽  
Author(s):  
David Sage
Keyword(s):  
Drug Testing ◽  
False Negative ◽  
Skin Tests ◽  
Positive Information ◽  
Positive Skin ◽  
Intradermal Testing ◽  
Negative Results ◽  
False Negative Results ◽  
Intravenous Anaesthetic ◽  
Anaphylactoid Reactions

Intradermal testing of intravenous anaesthetic drugs was performed on 34 patients following acute anaphylactoid reactions during anaesthesia. Twenty-three patients had positive skin tests and 18 of these were positive for a single drug. Muscle relaxants were the drugs implicated most commonly. Intradermal testing is safe and provides useful and often specific positive information, but false-negative results probably occur.

False-positive and false-negative rates in meconium drug testing

1995 ◽  
Vol 41 (11) ◽  
pp. 1614-1616 ◽  
Author(s):  
C Moore ◽  
D Lewis ◽  
J Leikin
Keyword(s):  
Mass Spectrometry ◽  
False Positive ◽  
Drug Testing ◽  
False Positive Rate ◽  
False Negative ◽  
Gas Chromatography Mass Spectrometry ◽  
Negative Results ◽  
False Negative Results ◽  
The Matrix ◽  
Positive Rate

Abstract To determine the number of false-negative results produced by inefficient extraction of drugs from meconium, three published procedures were compared by using previously confirmed positive and negative meconium specimens. The methods were not equivalent in their ability to extract drugs from the matrix. To determine the number of false positives reported by the use of screen-only (unconfirmed) results, 535 screen-positive meconium specimens were subjects to confirmation by gas chromatography-mass spectrometry. Fifty-seven percent of the samples were confirmed positive for one or more of the drugs under investigation, showing that a false-positive rate as high as 43% may exist when unconfirmed screening results are used.

Urine drug-testing tampering approaches: Turkish probationers

2020 ◽  
pp. 002580242095645
Author(s):  
Melike Aydoğdu ◽  
Serap Annette Akgür
Keyword(s):  
Screening Test ◽  
Drug Testing ◽  
False Negative ◽  
Drug Abusers ◽  
Eye Drops ◽  
Test Results ◽  
Positive Ratio ◽  
Negative Results ◽  
False Negative Results ◽  
Urine Drug

The growing numbers of individual and social problems associated with drug abuse necessitate new approaches in drug-testing systems. Equally, drug abusers may attempt to invalidate drug testing using different methods such as adulteration, dilution and substitution. This study aims to investigate tampering methods commonly used by Turkish substance-using probationers and evaluate their effects on toxicological drug-testing results. Initially, probationer urinary screening test results and laboratory substitution documents were evaluated to investigate the dilution and substitution attempt. Additionally, an experimental study was carried out by using readily available household products (bleach, vinegar, drain opener, eye drops) for adulteration. The effect of these agents was investigated for 11‐nor‐9‐carboxy-Δ9‐tetrahydrocannabinol (THC–COOH), amphetamine and 3,4-methylenedioxymethamphetamine (MDMA). It was determined that probationers preferred unbranded products (syringes, nylon bottles, etc.) for urine substitution. To detect dilution, screening test results were evaluated along with creatinine values. The variability of mean creatinine values can change the rate of the before-negative and after-positive ratio. For adulteration method, the high amounts of bleach provided false-negative results for THC–COOH and amphetamine, but spiking in any concentration of bleach affected MDMA results, causing a slight increase. Vinegar did not affect the THC–COOH and amphetamine results. However, false-negative results were observed for MDMA, with high amounts of vinegar-spiked urine samples. Drain opener was added in large quantities, and false-negative results were observed for all analytes. Visine eye drops did not have any effect on THC–COOH or amphetamine, but a high quantity of eye drops had a slight decreasing effect for MDMA.

Importance of creatinine analyses of urine when screening for abused drugs

1991 ◽  
Vol 37 (11) ◽  
pp. 1927-1931 ◽  
Author(s):  
P Lafolie ◽  
O Beck ◽  
G Blennow ◽  
L Boréus ◽  
S Borg ◽  
...  
Keyword(s):  
Drug Testing ◽  
Drugs Of Abuse ◽  
False Negative ◽  
Urine Samples ◽  
Heavy Smoker ◽  
Simple Method ◽  
Negative Results ◽  
False Negative Results ◽  
Abused Drugs ◽  
Urine Testing

Abstract We report here a simple method involving urine creatine measurements for testing authenticity and reducing false-negative results in urine testing for drugs of abuse. Urinary creatinine in consecutive patient samples (n = 176) ranged between 0.1 and 31.9 mmol/L (mean 9.8 +/- SD 6.2) and the osmolality in these urines ranged between 49 and 1183 mOsm/kg (mean 595 +/- SD 276). With other consecutive samples in which creatinine was (arbitrarily chosen) less than 4.3 mmol/L (n = 85), the correlation with osmolality was lower. In 10 randomly selected urine samples from different patients, all "clean" for all drugs of abuse in initial immunological drug testing with approved methodology (in which creatinine was less than 4.3 mmol/L and osmolality was less than 200 mOsm/kg), five patients turned out to be drug positive after a simple concentration by volume. In a formerly heavy smoker of cannabis, the excretion of cannabinoids and creatinine was monitored for 93 days. The substances showed very good correlation throughout this period (r = 0.93, P less than 0.001), whereas simple measurements of cannabinoid concentrations would have falsely indicated several relapses of cannabis abuse. Urine samples used in drug-abuse testing should be tested for creatinine; if creatinine is less than 4.0 mmol/L, negative results for drugs may not be valid.

EUTETIC MIXTURE OF LOCAL ANESTHETICS (EMLA) CREAM FOR PAINLESS SKIN TESTING: A PRELIMINARY REPORT

PEDIATRICS ◽  
1995 ◽  
Vol 96 (2) ◽  
pp. 384-384
Author(s):  
Betty Miller
Keyword(s):  
Local Anesthetics ◽  
Preliminary Report ◽  
Skin Testing ◽  
False Negative ◽  
Efficacy And Safety ◽  
Intradermal Testing ◽  
Emla Cream ◽  
Negative Results ◽  
False Negative Results

This study confirms the anesthetic efficacy and safety of EMLA cream. The EMLA cream did not interfere with the formation of wheals and flares and therefore did not jeopardize the purpose of intradermal skin testing. The recommended 1-hour wait was best for effective anesthesia. EMLA is not recommended for infants less than 1 month or for infants under 1 year of age who are receiving sulfonamide or methemoglobin-inducing agents. Because this is only a preliminary report, larger numbers of children need to be evaluated for false negative results when EMLA is used in conjunction with intradermal testing.

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.

Scoring System for the Diagnosis of COVID-19

2020 ◽  
Vol 13 (1) ◽  
pp. 413-414 ◽  
Author(s):  
Mohamed Farouk Allam
Keyword(s):  
Scoring System ◽  
Clinical Symptoms ◽  
False Negative ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Negative Results ◽  
False Negative Results ◽  
Symptoms And Signs

Due to the international spread of COVID-19, the difficulty of collecting nasopharyngeal swab specimen from all suspected patients, the costs of RT-PCR and CT, and the false negative results of RT-PCR assay in 41% of COVID-19 patients, a scoring system is needed to classify the suspected patients in order to determine the need for follow-up, home isolation, quarantine or the conduction of further investigations. A scoring system is proposed as a diagnostic tool for suspected patients. It includes Epidemiological Evidence of Exposure, Clinical Symptoms and Signs, and Investigations (if available). This scoring system is simple, could be calculated in a few minutes, and incorporates the main possible data/findings of any patient.

Detection of Streptococcus pneumoniae in Sputum Samples by Real- Time PCR.

2020 ◽  
Vol 18 ◽  
Author(s):  
Pegah Shakib ◽  
Mohammad Reza Zolfaghari
Keyword(s):  
Streptococcus Pneumoniae ◽  
Real Time ◽  
Real Time Pcr ◽  
False Negative ◽  
Cross Sectional Study ◽  
Laboratory Culture ◽  
Cross Sectional ◽  
Negative Results ◽  
False Negative Results ◽  
Pcr Method

Background: Conventional laboratory culture-based methods for diagnosis of Streptococcus pneumoniae are time-consuming and yield false negative results. Molecular methods including real-time (RT)-PCR rapid methods and conventional PCR due to higher sensitivity and accuracy have been replaced instead traditional culture assay. The aim of the current study was to evaluate lytA gene for detection of Streptococcus pneumoniae in the cerebrospinal fluid of human patients with meningitis using real-time PCR assay. Material and Methods: In this cross-sectional study, a total of 30 clinical specimens were collected from patients in a period from September to December 2018. In order to evaluate the presence of lytA gene, conventional and real-time PCR methods were used without culture. Results: From 30 sputum samples five (16.66%) isolates were identified as S. pneumoniae by lytA PCR and sequencing. Discussion: In this research, an accurate and rapid real-time PCR method was used, which is based on lytA gene for diagnosis of bacteria so that it can be diagnosed. Based on the sequencing results, the sensitivity for detection of lytA gene was 100% (5/5).

COVID-19: how nuclear medicine can provide a differential diagnosis in very dubious case

Coronaviruses ◽  
2020 ◽  
Vol 01 ◽  
Author(s):  
Maria Silvia De Feo ◽  
Viviana Frantellizzi ◽  
Giuseppe De Vincentis
Keyword(s):  
Infectious Disease ◽  
Differential Diagnosis ◽  
Ct Scan ◽  
Imaging Technique ◽  
False Negative ◽  
Clinical Signs ◽  
Negative Results ◽  
Infectious Disease Department ◽  
False Negative Results ◽  
99Mtc Hmpao

Background: We present the case of a 55-year-old woman, admitted to the Infectious Disease Department of Policlinico Umberto I, Rome, in mid-March 2020, with suspicion of COVID-19 infection. Objective: The rRT-PCR was negative and the following CT scan, performed to exclude false-negative results and help diagnosis, was inconclusive. Methods: It was decided to submit the patient to 99mTc-HMPAO-labelled leukocyte scan. Results: This exam led to the diagnosis of infective endocarditis. Conclusion: In the present pandemic scenario, 99mTc-HMPAO-labelled leukocyte scan represents a reliable imaging technique for differential diagnosis with COVID-19 in patients with confusing clinical signs, possible false-negative rRT-PCR results and inconclusive CT scan.

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