Clinical diagnosis of depression in primary care: a meta-analysis

BACKGROUND

Depression is a major burden for the health-care system worldwide. Most care for depression is delivered by general practitioners (GPs). We assessed the rate of true positives and negatives, and false positives and negatives in primary care when GPs make routine diagnoses of depression.

METHODS

We undertook a meta-analysis of 118 studies that assessed the accuracy of unassisted diagnoses of depression by GPs. 41 of these studies were included because they had a robust outcome standard of a structured or semi-structured interview.

FINDINGS

50 371 patients were pooled across 41 studies and examined. GPs correctly identified depression in 47.3% (95% CI 41.7% to 53.0%) of cases and recorded depression in their notes in 33.6% (22.4% to 45.7%). 19 studies assessed both rule-in and rule-out accuracy; from these studies, the weighted sensitivity was 50.1% (41.3% to 59.0%) and specificity was 81.3% (74.5% to 87.3%). At a rate of 21.9%, the positive predictive value was 42.0% (39.6% to 44.3%) and the negative predictive value was 85.8% (84.8% to 86.7%). This finding suggests that for every 100 unselected cases seen in primary care, there are more false positives (n=15) than either missed (n=10) or identified cases (n=10). Accuracy was improved with prospective examination over an extended period (3-12 months) rather than relying on a one-off assessment or case-note records.

INTERPRETATION

GPs can rule out depression in most people who are not depressed; however, the modest prevalence of depression in primary care means that misidentifications outnumber missed cases. Diagnosis could be improved by re-assessment of individuals who might have depression.

FUNDING

None.

Misdiagnosis due to gastrointestinal symptoms in an adolescent with probable autonomic status epilepticus and Panayiotopoulos syndrome

Panayiotopoulos syndrome is a common benign epilepsy affecting otherwise healthy children that present with autonomic seizures, in which nausea, retching, and vomiting are particularly common and prominent. Because of the unusual ictal symptoms and lengthy manifestations, misdiagnosis is a common major problem. We describe a young girl with intractable and lengthy vomiting attacks, several admissions to hospitals, and extensive gastroenterological workup for several years from early childhood. On all previous occasions the diagnosis varied from psychosomatic disease, to functional dyspepsia, to cyclic vomiting syndrome. The possibility of autonomic epileptic seizures and Panayiotopoulos syndrome, though likely, was not considered.

An uncommon skin condition illustrates the need for caution when prescribing for friends

PURPOSE

A dual-focused case study written to discuss the legal and medical hazards of informally writing prescriptions for friends or family members and to provide knowledge of early-stage mycosis fungoides (MF), its course, and treatment.

DATA SOURCES

A review of the prescribing practices of clinicians, the cognitive processes needed in diagnosis and treatment, the current ethical guidelines, and a review of MF, its course, and treatments.

CONCLUSIONS

Treating acquaintances and family informally places clinicians at risk for liability and patients at risk for inaccurate diagnosis and treatment. This case illustrates the potential hazard of casually treating a friend for what looks like a benign condition. Resembling atopic dermatitis in its early stages, MF is the most common of a rare group of skin lymphomas. Early diagnosis and treatment are crucial for a better prognosis. Had this clinician complied with the request of her friend, his diagnosis would have been missed and timely treatment delayed.

IMPLICATIONS FOR PRACTICE

No matter what the prior relationship may have been, once a clinician treats a patient, a legally binding relationship begins, requiring the due standard of care. Nurse practitioners (NPs) need to be aware of the potential for error when treating acquaintances. Available NP standards of practice and ethical guidelines should address informal treatment situations.

Effects of misdiagnosis in input data on the identification of differential expression genes in incipient Alzheimer patients

Gene expression profiles of 16 Alzheimer's (AD) patients, diagnosed as incipient or healthy using Mini-Mental State Examination and Neurofibrillary Tangles scores, were analyzed to validate the reclassification of 4 subjects previously identified as being misdiagnosed. Three datasets were created using original classifications (D1), new classifications, based on a misclassification algorithm (D2), and by removing questionable subjects (D3). Mixed model analysis was used to identify differentially expressed genes. Many genes related to the nervous system and AD were found to be differentially expressed in D2 and D3, while few genes, none related to NS or AD, were found using D1. Several additional relevant genes were found when using D2 versus D3, which were likely due to differences in sample size. These results suggest the 4 questionable subjects were likely misclassified in D1. The similarities between results obtained using D2 and D3 provides further evidence of the adequacy of the misclassification algorithm.

Potential misdiagnosis of 3-methylcrotonyl-coenzyme A carboxylase deficiency associated with absent or trace urinary 3-methylcrotonylglycine

We report 2 patients with isolated 3-methylcrotonyl-coenzyme A carboxylase deficiency whose urine was devoid of, or contained only trace, 3-methylcrotonylglycine, the pathognomonic marker for this disorder. The first patient, a girl with trisomy 21, was detected through newborn screening with an elevated 5 carbon hydroxycarnitine species level, and the second patient came to clinical attention at the age of 5 months because of failure to thrive and developmental delay. Investigation of urinary organic acids revealed an elevated 3-hydroxyisovaleric acid level but no demonstrable 3-methylcrotonylglycine in both patients. Enzyme studies in cultured fibroblasts confirmed isolated 3-methylcrotonyl-coenzyme A carboxylase deficiency with residual activities of 5% to 7% and 12% of the median control value, respectively. Incorporation of 14C-isovaleric acid into intact fibroblasts was essentially normal, showing that the overall pathway was at least partially functional and potentially explaining the absence of 3-methylcrotonylglycine in urine. Mutation analysis of the MCCA and MCCB genes revealed that both patients were compound heterozygous for a missense mutation, MCCB-c.1015G-->A (p.V339M), and a second mutation that leads to undetectable MCCB messenger (poly A+) RNA. Absent or trace 3-methylcrotonylglycine levels in urine raises the potential for misdiagnosis in the clinical biochemical genetics laboratory based solely on urine organic acid analysis using combined gas chromatography-mass spectrometry.

Relative performance of three methods for diagnosing bacterial vaginosis during pregnancy

OBJECTIVE

This study measures the relative performance of three methods for diagnosing bacterial vaginosis (BV) during pregnancy and assesses the implications of measurement for clinical practice and surveillance.

METHODS

A sample (n = 1,780) of English or Spanish speaking women, with a singleton intrauterine pregnancy and receiving prenatal care at a consortium of public health centers in Philadelphia were consecutively enrolled. Gram stain, clinician's diagnosis, and a commercial test were the three diagnostic methods used to assess BV. Sensitivity, specificity, and the positive and negative predictive values of clinical diagnosis and the commercial test were assessed using the gram stain/Nugent score as a gold standard.

RESULTS

The prevalence of BV, measured on the same population, differed considerably depending on the diagnostic test used. The measured prevalences were 55% (Gram stain), 28.5% (clinician's diagnosis), and 12.6% (commercial test). The prevalence of BV (diagnosed by gram stain) was twice as high among African American women compared to White women. Only 69% BV-positive high-risk women were treated for BV.

CONCLUSIONS

Inaccurate diagnosis of BV leads to missed cases. The identification of true cases is critical for assigning treatment and for assessing treatment effectiveness. Clinician's routine diagnosis fell short of recommended procedures and performed poorly compared to gold standard in case ascertainment. This inability to ascertain cases may have an impact on our ability to prevent preterm birth.

Tc-99m ECD Neuro-SPECT and Diffusion Weighted MRI in the Detection of the Anatomical Extent of Subacute Stroke

We present a case of subacute middle cerebral artery infarct, which demonstrates restricted diffusion on MRI and reperfusion hyperemia in the posterior half of the lesion on angiography. Tc-99m ethyl cysteinate dimer (ECD) SPECT obtained shortly after the MRI failed to demonstrate perfusion defects in the regions demonstrating reperfusion hyperemia on angiography, underestimating the true size of the infarct. Crossed cerebellar diaschisis is, however, present. SPECT studies obtained over the following weeks demonstrated gradual enlargement of the lesion to approximate the MRI signal changes over a 19-day period. The case presented demonstrates retention of ECD in the infarcted brain. Several studies have demonstrated that Tc-99m ECD uptake is dependent on preserved brain tissue function because tracer retention requires enzymatic esterase activity, rather than the passive, nonenergy dependent trapping of Tc-99m hexamethylpropyleneamine oxime. Hence, infarcted areas undergoing reperfusion hyperemia are unlikely to demonstrate ECD uptake. This report illustrates that MRI diffusion weighted imaging may be more accurate in demonstrating the full extent of reperfused infarcts earlier than Tc-99m ECD SPECT. SPECT in this case failed to demonstrate reduced uptake in reperfused regions of the infarct. Also, crossed cerebellar diaschisis may serve as an early marker of extensive neuronal dysfunction.

2B or not 2B? Disparate discrimination of functional VWF discordance using different assay panels or methodologies may lead to success or failure in the early identification of type 2B VWD

Laboratory proficiency in the identification of functional von Willebrand factor (VWF) discordance in type 2B von Willebrand disease (VWD) was assessed by external quality assurance surveys conducted by the RCPA Haematology QAP, and using six different type 2B VWD plasma samples (three historical and three previously unpublished) tested by up to 52 laboratories. For the three most recent samples, functional VWF discordance was either not identified in testing or by interpretation with misidentification as 'normal' or 'type 1 VWD', on average for 25.7% of test occasions when laboratories performed VWF:Ag and VWF:RCo as their primary VWF test panel, but somewhat fewer occasions (10.9%) for laboratories that incorporated VWF:CB as an additional functional VWF assay. VWF assay sub-methodologies also influenced the appropriate identification of samples as potentially type 2 VWD, and VWF functional discordance was more consistently identified when laboratories used (i) automated platelet agglutination for VWF:RCo compared to classical platelet aggregometry, (ii) inhouse VWF:CB assays compared to commercial kit methods, and (iii) automated LIA-based 'VWF:Activity' assays compared to ELISA based assays. We conclude that:(i) laboratories are generally proficient in tests for VWD but interpretative diagnostic errors do occur; (ii) correct diagnosis is more likely when test panels are more comprehensive and include the VWF:CB; (iii) sub-methodology influences the appropriate identification of VWF functional discordance. On the basis of these findings, we provide a series of recommendations to enable the appropriate laboratory identification of VWD, in particular type 2B VWD.

Delayed recognition of a pseudo-outbreak of Mycobacterium terrae

Pseudo-outbreaks of mycobacteria are difficult to recognize because of long incubation periods for growth and species identification. We report our experience with one clinical microbiology laboratory that isolated a species of nontuberculous mycobacteria from 14 patient specimens. These specimens came from 12 patients at 2 hospitals over a 6-day period and included 6 different fluids or tissues. Because of the delay between mycobacterial specimen submission and growth in culture, the outbreak was not noted until more than a month later. Initial species determination by a reference laboratory indicated that these isolates were Mycobacterium fortuitum. One patient received treatment for presumed M fortuitum brain infection, and it was not effective in changing her clinical course. The isolates were sent to the Centers for Disease Control and Prevention (CDC) for identification and typing by pulsed-field gel electrophoresis. The CDC determined that the isolates were an identical strain of M terrae, thus confirming a pseudo-outbreak. Combining pseudo-outbreak isolates with those correctly identified initially as M terrae during the 6-day period in question, there were 22 samples from 20 patients with M terrae. Since the pseudo-outbreak, the number of cultures of M terrae in the clinical laboratory has returned to baseline levels without any specific intervention.

Common Misdiagnosis of a Common Neurological Disorder

BACKGROUND

As a common neurological disorder, the diagnosis of essential tremor (ET) is considered routine. Despite this, previous work suggests that misdiagnoses may be common. Among other things, these misdiagnoses can lead to treatment errors.

OBJECTIVES

To estimate how often other tremor disorders are misdiagnosed as ET and to identify factors that increase the odds of misdiagnosing ET and to precisely quantify the extent to which they do so.

DESIGN

Seventy-one consecutive patients underwent an evaluation at the Neurological Institute of New York, New York, between January 1, 2000, and December 31, 2005; these patients had a pre-evaluation diagnosis of ET. The criteria for ET were adapted from the consensus statement of the Movement Disorder Society.

RESULTS

Twenty-six patients (37%) were misdiagnosed as having ET ("false ET"). Their true diagnoses were Parkinson disease (11 patients [15%]), dystonia (6 patients [8%]), Parkinson disease with ET (5 patients [7%]), and other disorders (4 patients [6%]). Factors associated with misdiagnosed ET included unilateral arm tremor (odds ratio, 10.5; 95% confidence interval, 1.2-95.4; P=.02), spooning of the hands and other dystonic postures (odds ratio, 16.3; 95% confidence interval, 4.0-66.4; P<.001), and other unusual features (isolated thumb tremor, isolated leg tremor, and non-rhythmic tremor) (odds ratio, 49.4; 95% confidence interval, 2.7-895.0; P<.001).

CONCLUSIONS

About 1 in 3 patients with tremor was misdiagnosed as having ET, with the most frequent false diagnoses being Parkinson disease and dystonia. Several factors that increased the odds of misdiagnosing ET were identified. These factors could be incorporated into improved diagnostic algorithms.

Reducing Missed Injuries at a Level II Trauma Center

The phenomenon of missed injury in trauma patients has been recognized for some time. Tertiary examination has been proposed as one strategy to decrease the incidence of missed injuries. The tertiary examination is a comprehensive reevaluation that includes a repeated head-to-toe examination and review of all laboratory and radiologic studies, completed within 24 hours of admission. The purpose of this study was to assess the statistical significance of missed injuries discovered through tertiary examinations at a level II trauma center. Over a period of 6 months, a tertiary examination was completed before discharge of admitted patients who met activation criteria. Of the 90 patients, 13 had a missed injury (incidence of 14%), which was significant. The 16 missed injuries represented only 2.7% of the total 589 injuries, which was not significant. The most commonly missed injuries were fractures of the extremities. We propose that tertiary examinations be adopted as a standard of care for patients admitted to level II trauma centers.

Comparing methods to measure error in gynecologic cytology and surgical pathology

CONTEXT

Both gynecologic cytology and surgical pathology use similar methods to measure diagnostic error, but differences exist between how these methods have been applied in the 2 fields.

OBJECTIVE

To compare the application of methods of error detection in gynecologic cytology and surgical pathology.

DATA SOURCES

Review of the literature.

CONCLUSIONS

There are several different approaches to measuring error, all of which have limitations. Measuring error using reproducibility as the gold standard is a common method to determine error. While error rates in gynecologic cytology are well characterized and methods for objectively assessing error in the legal setting have been developed, meaningful methods to measure error rates in clinical practice are not commonly used and little is known about the error rates in this setting. In contrast, in surgical pathology the error rates are not as well characterized and methods for assessing error in the legal setting are not as well defined, but methods to measure error in actual clinical practice have been characterized and preliminary data from these methods are now available concerning the error rates in this setting.

Are Occult Pneumothoraces Truly Occult or Simply Missed?

BACKGROUND

Nonradiologists typically diagnose pneumothoraces (PTX) based on a visible pleural stripe. PTXs not seen on supine AP chest radiographs (CXR), but appreciated on a computed tomographic (CT) scan, termed occult pneumothoraces (OPTX), are increasingly common. The purpose was to (1) determine whether perceived OPTXs were truly occult or simply missed and (2) address factors that contribute to the poor sensitivity of the supine CXR.

METHODS

A previous study of severely injured patients (ISS >or =12) identified 44 patients with OPTXs. JPEG images of these CXRs were randomly arranged with images of 11 injured patients without PTXs (CT proven). Three unique groups of radiologists reviewed the images for signs of PTXs, and determined if a thoracic CT was subsequently required.

RESULTS

Retrospective review identified only 12 to 24% of the OPTXs depending on radiology group. The kappa inter-observer agreement value was 0.55 to 0.56 (poor agreement). PTXs were most commonly identified via the deep sulcus sign (75-90%). CXRs were considered inadequate in 16 to 25% of OPTX images and in 0 to 18% of images without OPTXs. Thoracic CT scans were recommended in 18 to 33% of patients with inadequate CXRs, but 67 to 82% of patients with adequate CXRs.

CONCLUSIONS

Less than 24% of all OPTXs might have been inferred from subtle radiologic findings, such as the deep sulcus sign. The majority of OPTX cases (50-64%) did not warrant a CT scan based on other findings. Concern for an OPTX after severe trauma is a valid indication for thoracic CT.

Erroneous Left ventricular cavity size measurements on myocardial perfusion SPECT resulting from transient arrhythmias

Transient ischemic dilatation (TID) of the left ventricle during stress on myocardial perfusion imaging is a sign of severe coronary artery disease. Factors other than ischemia can transiently influence left ventricular size, however, and TID ratios can be misleading if these factors are not properly identified. We describe 4 cases of stress-rest Tc-99m sestamibi SPECT myocardial perfusion imaging in which both abnormally high and low TID ratios were seen as a result of the presence of transient supraventricular tachyarrhythmias that reduced cardiac filling time and corresponding left ventricular volumes.

Mineral content changes in bone associated with damage induced by the electron beam

Energy-dispersive x-ray (EDX) spectroscopy and backscattered electron (BSE) imaging are finding increased use for determining mineral content in microscopic regions of bone. Electron beam bombardment, however, can damage the tissue, leading to erroneous interpretations of mineral content. We performed elemental (EDX) and mineral content (BSE) analyses on bone tissue in order to quantify observable deleterious effects in the context of (1) prolonged scanning time, (2) scan versus point (spot) mode, (3) low versus high magnification, and (4) embedding in poly-methylmethacrylate (PMMA). Undemineralized cortical bone specimens from adult human femora were examined in three groups: 200x embedded, 200x unembedded, and 1000x embedded. Coupled BSE/EDX analyses were conducted five consecutive times, with no location analyzed more than five times. Variation in the relative proportions of calcium (Ca), phosphorous (P), and carbon (C) were measured using EDX spectroscopy, and mineral content variations were inferred from changes in mean gray levels ("atomic number contrast") in BSE images captured at 20 keV. In point mode at 200x, the embedded specimens exhibited a significant increase in Ca by the second measurement (7.2%, p < 0.05); in scan mode, a small and statistically nonsignificant increase (1.0%) was seen by the second measurement. Changes in P were similar, although the increases were less. The apparent increases in Ca and P likely result from decreases in C: -3.2% (p < 0.05) in point mode and -0.3% in scan mode by the second measurement. Analysis of unembedded specimens showed similar results. In contrast to embedded specimens at 200x, 1000x data showed significantly larger variations in the proportions of Ca, P, and C by the second or third measurement in scan and point mode. At both magnifications, BSE image gray level values increased (suggesting increased mineral content) by the second measurement, with increases up to 23% in point mode. These results show that mineral content measurements can be reliable when using coupled BSE/EDX analyses in PMMA-embedded bone if lower magnifications are used in scan mode and if prolonged exposure to the electron beam is avoided. When point mode is used to analyze minute regions, adjustments in accelerating voltages and probe current may be required to minimize damage.

Failure to diagnose: subarachnoid haemorrhage

Case histories are based on actual medical negligence claims, however certain facts have been omitted or changed by the author to ensure the anonymity of the parties involved. This article examines the diagnosis of subarachnoid haemorrhage (SAH), a rare but serious cause of headache in general practice. On occasion, the diagnosis of SAH is missed or delayed, usually because the condition was not considered in the differential diagnosis.

Failure of Observation of Blunt Splenic Injury in Adults: Variability in Practice and Adverse Consequences

BACKGROUND

The Eastern Association for the Surgery of Trauma Multiinstitutional Workgroup reported a failure rate for nonoperative management of blunt splenic injury in adults of 10.8%. Sixty percent of the failures occurred within 24 hours of admission. The purpose of this multiinstitutional study by the Eastern Association for the Surgery of Trauma was to determine common variables in failure of nonoperative management of blunt splenic injury in adults.

STUDY DESIGN

Medical records were reviewed in a blinded fashion on 78 patients in whom nonoperative management failed. Statistical analysis was performed with ANOVA, extended chi-square, and Fisher's exact test; statistical significance was p<0.05.

RESULTS

The 78 patients were categorized based on hemodynamic status. Forty-four percent were stable; 31% had transient hypotension or tachycardia that resolved with fluid infusion (responders); and 25% were unstable. Two-thirds of the unstable patients required laparotomy within 12 hours of admission; all had laparotomy within 72 hours. Mortality was significantly different when comparing the unstable to the stable and responder groups: stable (3%), responders (8%), and unstable (37%), despite similar age and only modest differences in Injury Severity Score. Eight CT scans were misinterpreted initially. Of 26 Focused Abdominal Sonography for Trauma (FAST) studies, 11 (42.3%) were false negative. Abnormal abdominal findings were noted in 67.7% of patients on admission. Ten patients died (12.8%). Sixty percent of the deaths were caused largely by delayed treatment of splenic or other abdominal injuries; one patient died in the responder group and five unstable patients died.

CONCLUSIONS

Thirty percent to 40% of the patients who had unsuccessful nonoperative management in this study were selected inappropriately, with hemodynamic instability or initial misinterpretation of diagnostic studies. As a consequence, the majority of the deaths were from delayed treatment of intraabdominal injuries. This article suggests that written protocols, better adherence to sound clinical judgment, and experienced and timely interpretation of radiologic studies would reduce the incidence of failure of nonoperative management of blunt splenic injury in adults.

Spurious Hypocalcemia After Omniscan- or OptiMARK-Enhanced Magnetic Resonance Imaging: An Algorithm for Minimizing a False-Positive Laboratory Value

Contrast-enhanced magnetic resonance imaging has become a routine diagnostic imaging procedure. Reports in the literature document that 2 of the 4 available gadolinium-based magnetic resonance imaging contrast agents, gadodiamide (Omniscan) and gadoversetamide (OptiMARK), are less stable and readily undergo dechelation. In vitro, this dechelation can result in interference with the most common laboratory methods used to measure total plasma or serum calcium. The result of total calcium measurement soon after contrast-enhanced magnetic resonance imaging with these interfering contrast agents is a spurious lowering of the total calcium level. This low calcium measurement may result in a value consistent with hypocalcemia and can persist in patients with renal insufficiency and in patients receiving higher doses of contrast agent. Alternatively, a clinically significant elevated calcium level may be overlooked because of the artificially lowered value. Two of the available gadolinium-based contrast agents, gadoteridol (ProHance) and gadopentetate dimeglumine (Magnevist), have not been to shown to interfere with total calcium measurement. A clinical practice algorithm for the laboratorian, the radiologist, and the clinician is presented to minimize the occurrence and consequences of a spuriously lowered total calcium level due to Omniscan- or OptiMARK-enhanced magnetic resonance imaging.

Missed acute cardiac ischemia in the ED: limitations of diagnostic testing

Correctly identifying and appropriately triaging patients who present to the ED with the broad range of symptoms suggestive of acute cardiac ischemia (ACI: unstable angina pectoris [UAP] and acute myocardial infarction [AMI]) remains one of the greatest challenges in EM. Although a number of diagnostic technologies have been described to aid in this triage process, each of these tests or technologies has limitations. We report a case series in which either the use of adjuncts with unknown performance or tests with known but not considered limitations could have contributed to the failure to appropriately triage and treat patients with ACI. Each case illustrates different aspects of this clinical challenge. One case illustrates the hazards of reliance on a single set of negative cardiac biomarkers. The limitations of a negative exercise electrocardiographic stress test (ETT) are illustrated in the second case. Finally, the limitations of a negative coronary angiogram, the "gold standard" test for symptomatic coronary artery disease, are discussed. We review the literature on technologies to aid in the evaluation of patients who present to the ED with symptoms suggestive of ACI.

Common artifacts in PET myocardial perfusion images due to attenuation-emission misregistration: clinical significance, causes, and solutions

Misregistration between attenuation and emission images causes artifactual abnormalities on cardiac PET images that result in false-positive defects. This study determines the frequency and mechanisms of misregistration artifacts, identifies their predictors, and validates a method for their routine clinical identification, prevention, or correction.

METHODS

We performed 1177 consecutive diagnostic myocardial perfusion PET studies using 1 of 3 protocols: (a). 3 initial consecutive measured attenuation correction (MAC) scans, followed by resting and dipyridamole emission scans; (b). an initial MAC scan (early MAC), followed by emission scans; and (c). a MAC attenuation scan obtained after emission scans (late MAC). Emission images were manually shifted to obtain coregistration with attenuation and reconstructed again using shifted emission data that eliminated artifactual defects. Measurements on PET images included heart size, heart and diaphragm displacement after dipyridamole, objective quantitative misregistration of attenuation and emission images, and size or severity of image defects before and after shifting emission images.

RESULTS

Of 1,177 rest-dipyridamole PET perfusion studies, 252 (21.4%) had artifactual defects due to attenuation-emission misregistration. By shifting emission images, quantitative severity and size of misregistration and artifactual defects significantly decreased (P < 0.001) with visual normalization. Artifactual defects were predicted by horizontal plane misregistration (odds ratio [OR] = 1.545, confidence intervals [CI] = 1.113-2.145, P = 0.009), body mass index (OR = 2.659, CI = 1.032-6.855, P = 0.043), and whole heart area in the horizontal plane at rest (OR = 1.096, CI = 1.018-1.179, P = 0.015). Quantitative misregistration was predicted by diaphragm displacement between rest and dipyridamole (P = 0.001, CI = 0.158-0.630), body mass index (P = 0.005, CI = 0.202-1.124), and whole heart area in the horizontal plane at rest (P = 0.004, CI = -0.144 to -0.028). Diaphragm displacement was significantly larger for obese compared with lean patients (P = 0.027) during the initial 10 min of the imaging protocol.

CONCLUSION

Misregistration of attenuation and emission images is common in cardiac PET imaging and causes artifactual defects predicted by diaphragmatic displacement, body mass index, and heart size. Multiattenuation imaging sequences and manual, visually optimized coregistration of attenuation and emission images substantially eliminate artifacts for reliably identifying mild perfusion defects of early nonobstructive coronary atherosclerosis as the basis for intense lifestyle and pharmacologic treatment.

Clinical reasoning: the relative contribution of identification, interpretation and hypothesis errors to misdiagnosis

The aim of this study was to identify and describe the types of errors in clinical reasoning that contribute to poor diagnostic performance at different levels of medical training and experience. Three cohorts of subjects, second- and fourth- (final) year medical students and a group of general practitioners, completed a set of clinical reasoning problems. The responses of those whose scores fell below the 25th centile were analysed to establish the stage of the clinical reasoning process--identification of relevant information, interpretation or hypothesis generation--at which most errors occurred and whether this was dependent on problem difficulty and level of medical experience. Results indicate that hypothesis errors decrease as expertise increases but that identification and interpretation errors increase. This may be due to inappropriate use of pattern recognition or to failure of the knowledge base. Furthermore, although hypothesis errors increased in line with problem difficulty, identification and interpretation errors decreased. A possible explanation is that as problem difficulty increases, subjects at all levels of expertise are less able to differentiate between relevant and irrelevant clinical features and so give equal consideration to all information contained within a case. It is concluded that the development of clinical reasoning in medical students throughout the course of their pre-clinical and clinical education may be enhanced by both an analysis of the clinical reasoning process and a specific focus on each of the stages at which errors commonly occur.

Enhancing recovery of endocervical component on gynecologic cytology specimens processed by thin-layer technology

OBJECTIVE

To address the causes and report the corrective measures required for resolving the initial problem of high rates of cervical vaginal cytology specimens reported as having no endocervical component on SurePath (AutoCyte, Inc., Burlington, North Carolina, U.S.A.) liquid-based, thin-layer technology at an academic center cytology laboratory.

STUDY DESIGN

Analysis of 511 cases lacking endocervical/transformation zone component out of 9,221 SurePath thin-layer gynecologic specimens processed in a one-year period. The study encompassed a review of sample collection techniques by physicians and nurses, specimen processing, cytologic features of endocervical/squamous metaplastic cells processed by the SurePath method and statistical analysis of endocervical cell recovery rates after implementation of corrective measures.

RESULTS

Absence of endocervical/transformation zone component varied from an initial 18% in the first month to an average of 5.3% after corrective actions were implemented. Current rates of SurePath thin-layer specimens having no endocervical component are lower than those for conventional smears.

CONCLUSION

Since SurePath was only recently introduced to the market, there are no previously published data addressing how to optimize the recovery of endocervical component on liquid-based, thin-layer specimens processed by this methodology.

Mid-trimester ultrasound prediction of gestational age: advantages and systematic errors

OBJECTIVE

To detect possible sources of bias in ultrasound prediction of gestational age.

SUBJECTS AND METHODS

Using the Swedish Medical Birth Registry, 571 617 women were identified who were delivered between 1990 and 1997 and who had obtainable information on last menstrual period and expected date of delivery according to ultrasound.

RESULTS

Male fetuses were more likely than females to be judged older than the last menstrual period date suggested at early fetometry. The estimated magnitude of the systematic error by infant gender corresponded to 1.5 days. Similarly, the fetuses of young women, multiparous women, smokers and women with low educational level were at increased risk of being smaller than expected at ultrasound examination in early pregnancy. A strong association was seen between adjustments of expected date of delivery -7 days or more and small-for-gestational age according to ultrasound at birth. Compared to singleton pregnancies, twin pregnancies were more likely to be judged more progressed at ultrasound fetometry than the last menstrual period date suggested.

CONCLUSIONS

Compared to last menstrual period estimates, routine ultrasound measurements to predict date of delivery are comparatively reliable but systematic errors are inherent in the method. The erroneous adjusted dates may be due to incorrect measurements or systematic bias (e.g. gender), but they are also likely to reflect early growth restriction (e.g. in the case of maternal smoking and small-for-gestational age). Further studies are needed to investigate whether the systematic errors in ultrasound prediction of gestational age could lead to suboptimal obstetric management in adjusted pregnancies.

Intraoperative cholangiography is still indicated after preoperative endoscopic cholangiography for gallstone disease

BACKGROUND

Intraoperative cholangiography (IOC) is frequently omitted in patients undergoing laparoscopic cholecystectomy (LC) if they have had successful preoperative endoscopic retrograde cholangiography (ERC).

METHODS

A prospectively maintained divisional laparoscopic cholecystectomy database was searched from 1991 to 1997 for patients who had IOC after preoperative ERC. The presence of recurrent or residual common duct stones seen on IOC and their impact on subsequent management were evaluated.

RESULTS

We identified a group of 127 patients who underwent preoperative ERC. Thirty-one patients (31/127, or 24%) went on to receive an IOC during cholecystectomy. In 15 patients whose preoperative ERC was reported normal, five (33%) had an abnormal IOC. In 16 patients whose ERC was reported as having cleared the duct, eight (50%) had an IOC abnormality. Eight of these 31 patients required a further procedure to clear the duct.

CONCLUSION

Retained or recurrent common duct stones at cholecystectomy following diagnostic or therapeutic ERC were more common than expected. Therefore, IOC is recommended during LC regardless of the findings yielded by the preoperative ERC.

An approach to dissecting the congenitally malformed heart in the forensic autopsy: the value of sequential segmental analysis

The demonstration of congenital heart disease at autopsy necessitates the careful preservation and examination of the heart, the vessels, and their connections. Techniques preserving these connections and using a reproducible and systematic approach are preferred. The Rokitansky method of organ block dissection, in combination with a system of heart examination termed sequential segmental analysis, provides such an approach. This study is based on the examination of heart specimens accessioned into the Frank E. Sherman, M.D., and Cora C. Lenox, M.D., Heart Museum (containing approximately 2400 specimens) of the Pathology Department, Children's Hospital of Pittsburgh. Specimens received in consultation during a 25-year period from hospitals and coroners'/medical examiners' offices were examined, and the corresponding reports were reviewed. Of 46 total heart specimens examined (1975-1999), 29 (63%) were dissected properly or left intact for dissection at Children's Hospital of Pittsburgh, and 17 (37%) were incorrectly dissected for the demonstration of congenital heart disease. Of these 17 cases, 11 (24%) displayed dissection errors, which did not hinder a complete diagnosis, 3 cases (6.5%) had errors that enabled only an incomplete diagnosis, and in 3 cases (6.5%), no diagnosis of congenital heart disease could be made. Dissection mistakes and means of avoiding them are discussed. Review of medical and family history, external and internal examination, and a reproducible and sequential method of examining the heart and its connections enables documentation of even the most complex cardiovascular anomalies.

Delayed diagnosis in pediatric blunt trauma

OBJECTIVE

Identification of injuries of a traumatized patient is a mandate for the emergency department (ED) and the trauma team. Delayed diagnosis of injury in trauma patients leads to increased morbidity, mortality, dissatisfaction, and risk of litigation. Comparing children admitted for blunt trauma, with and without delay, this study examines risk factors for delayed diagnosis.

METHODS

Delays in diagnosis from 1991 to 1996 were identified during prospective collection of trauma registry data. Controls were randomly selected from the trauma registry. Charts from both groups were retrospectively reviewed.

RESULTS

Fifty-eight patients had 65 delays in diagnosis. Significant independent delay variables included: female, motor vehicle crash (MVC)-related mechanism, altered consciousness, higher injury severity score, and multiple injuries (P < 0.05). Trauma team activation, documentation of tertiary survey, and length of hospitalization were greater in patients with delay injuries (P < 0.05). Logistic regression identified MVC-related mechanism, female, facial, and extremity injuries as a combination of predictors.

CONCLUSIONS

Delays occurred in 1% of patients. Trauma team care itself did not protect all patients from delay. Injury severity at presentation alone is not an adequate predictor of delayed diagnosis in the pediatric patient. A combination of variables was identified as negative predictors of delay. Further study is needed to validate these criteria, and determine if earlier diagnosis would effect quality.

Psoas abscess: a primer for the internist

Psoas abscess is a rare condition with vague clinical presentation. In this article, its epidemiology, etiology, bacteriology, diagnosis, and treatment are discussed. Common diseases that may be erroneously diagnosed in patients with psoas abscess are presented.

Plasma creatinine assessment in creatine deficiency: A diagnostic pitfall

Guanidinoacetate methyltransferase (GAMT) deficiency (creatine deficiency syndrome) is a recently discovered inborn error of creatine biosynthesis. Affected patients have elevated concentrations of guanidino-acetate, the metabolic precursor of creatine, in urine, plasma and cerebrospinal fluid. In addition, urinary creatinine excretion and plasma creatinine concentration are decreased. For biochemical evaluation of patients suspected to suffer from GAMT deficiency, correct quantification of creatinine in plasma is important. Here we report our experience with different quantification techniques. We found that creatinine in plasma from two GAMT-deficient patients appeared normal when measured by the Jaffé method but was decreased when measured enzymatically or by HPLC. The apparently normal levels of creatinine as measured by the Jaffé method were not caused by guanidinoacetate. In urine, the Jaffé method and the enzymatic method gave similar results, indicating that in urine no false elevations of creatinine can be expected. As the Jaffé method is still widely used for routine plasma creatinine measurements, it is important to realize it cannot be used to exclude GAMT deficiency.

Single-nucleotide polymorphisms may cause erroneous results in primer-introduced restriction enzyme analyses: a case of molecular misdiagnosis of homozygous vs heterozygous familial hypercholesterolemia

PCR amplification followed by a primer introduced restriction analysis PCR (PIRA-PCR) is a widely used method to detect point mutations. Usually the artificial RFLP is created by siting one nucleotide mismatch near the 3; end of the primer. This does not alter the hybrization of the primer to the target DNA sequence. Unfortunately, unexpected single nucleotide polymorphisms (SNPs) may lead to additional mismatches and result in no amplification of the allele having unexpected SNP. We describe a warning example in which heterozygous familial hypercholesterolemia patient had an unexpected SNP and this led to his misdiagnosis.

Observer sensitivity to small differences: a multipoint rank-order experiment

OBJECTIVE

To evaluate observer sensitivity to small differences in image presentation, a multipoint rank-order experiment was used to identify small differences or trends in observations.

MATERIALS AND METHODS

Ten observers were presented with 50 sets of breast images that had been compressed at five different levels. Each set contained six images ranging from noncompressed to approximately 101:1 compression. Observers were asked to review all images of a case side by side and rank order the quality of each to enable determination of the presence or absence of masses and clustered microcalcifications.

RESULTS

As a group, observers were able to detect small differences among the images, even at the lower compression levels (p < .001). As compression levels and image degradation increased, the ability to identify differences between different modes also increased. Large observer variability in discrimination ability was observed.

CONCLUSION

Multipoint rank ordering of images viewed side by side can be an efficient method to identify small differences in image presentation. This approach to image ranking could be used to rule out or confirm the need for objective observer performance-type studies.

Submission of lymph node tissue for ancillary studies decreases the accuracy of conventional breast cancer axillary node staging

Pathologists are under increasing pressure to submit fresh tissue for ancillary studies and research protocols. In several tumor types (breast, lung, melanoma, colorectal, prostate), increased interest in detecting submicroscopic nodal metastases through reverse transcriptase polymerase chain reaction analysis of mRNA from portions of lymph nodes has precluded histologic analysis of the entire node for metastases. A retrospective review was undertaken of 227 breast cancer patients prospectively entered on a research protocol examining the usefulness of sentinel lymph node surgery. All of the patients ultimately underwent complete lymph node dissection. The research protocol required that all nodes greater than 8 mm in size be bisected and submitted separately. Positive lymph nodes were evaluated for unilateral or bilateral involvement in the node sections. Sixty node-positive patients were identified, yielding 230 positive nodes. One hundred seven of these nodes were confirmed to have been bisected. Carcinoma was identified in both lymph node sections in 64 (59.8%) nodes and in only one-half of the bisected lymph node in 43 (40.2%) nodes. Involvement of both sections was more likely when patients had multiple nodes positive. In 12 patients, involvement of one-half of the bisected nodes was the only evidence of metastatic disease (20.0% of node-positive patients). This evidence suggests that submission of less than the complete lymph node for histologic evaluation of metastatic disease decreases the accuracy of lymph node staging. Furthermore, a significant proportion of patients may be erroneously classified as histologically node negative.

Bayesian estimates of error bounds for EEG source imaging

Given a set of electrical potential measurements at the surface of the head, localizing the sources of the electrical activity is an inherently ill-posed problem. Bayesian methods can be used to specify prior information to constrain the possible source solutions. We show that Bayesian analysis can also provide a means for characterizing system noise levels, estimating the "error bars" surrounding source localization results, and estimating the information about brain processes conveyed by dense sensor array electroencephalographic (EEG) recordings. This method is, in principal, applicable to any linear model of EEG or magnetoencephalographic (MEG) processes. A series of simulations demonstrated the internal consistency of our method, the robustness to noise levels, and the limitations of accurate source localization with large numbers of sources.

Correction of errors caused by imperfect inversion pulses in MR imaging measurement of T1 relaxation times

Spin-lattice (T1) relaxation times were measured by an inversion-recovery magnetic resonance imaging method with a slice-selective inversion pulse (SIP), a non-selective rectangular inversion pulse (RIP), or a B1-insensitive adiabatic inversion pulse (AIP). Data analysis either assumed perfect inversion (two-parameter fit) or allowed for imperfect inversion (three-parameter fit). Imperfect inversion pulses caused low T1 values in phantoms with a two-parameter fit, while three-parameter T1 estimates were accurate over the range 430-2670 ms. A difference of approximately 10% between two-parameter and three-parameter T1 values in normal human brain tissue was attributed to B1 inhomogeneity with the slice-selective inversion pulse and rectangular inversion pulse, to the slice profile with the slice-selective inversion pulse, and to T2 effects for the adiabatic inversion pulse. Any T1 method that relies on accurate flip angles may have a significant systematic error in vivo. Phantom accuracy does not ensure accuracy in vivo, because phantoms may have a more homogeneous B1 field and a longer T2 than do biological samples.