Correspondence

Emergency department ultrasound: Impact on ed stay times

Emergency physician–performed ultrasonography holds promise as a rapid and accurate method to diagnose multiple diseases in the emergency department (ED). Our objective was to assess the initial diagnostic accuracy (first 55 explorations) of emergency physician–performed ultrasonography for multiple categories of ultrasound use after a short training period.

This was a prospective observational study conducted at an urban ED from June 2010 to March 2011 in patients with suspected cholecystitis, hydronephrosis, deep vein thrombosis, and different cardiovascular problems. Five physicians had a 10-hour training session before enrolling patients. The test characteristics of bedside ultrasonography were determined with the final radiologist/cardiologist interpretation.

A total of 275 ultrasonographic examinations were performed (78 abdominal explorations, 80 renal explorations, 76 2-point compression ultrasonographic examinations in patients with suspected deep vein thrombosis, and 41 echocardiograms in patients with different acute cardiovascular problems). Radiologists/cardiologists detected 28 cases of cholecystitis, 26 cases of deep vein thrombosis, 49 cases of hydronephrosis, and 15 cases of significant cardiovascular alterations. The overall diagnostic accuracy of ED ultrasonograms yielded a sensitivity, specificity, positive predictive value, and negative predictive value of 92.6% (95% confidence interval [CI], 90%-99%), 89% (95% CI, 84%-94%), 86.2 % (95% CI, 82%-93%), and 94.2% (95% CI, 92%-99%), respectively. Nineteen (6.9%) false-positive results and 6 false-negative results (2.1%) were obtained.

Emergency physicians in our institution attained reasonably high initial accuracy in the performance of ultrasonography for a variety of clinical problems after a 10-hour training period.

Ectopic pregnancy is a common concern in emergency departments (EDs) and remains the leading cause of first-trimester mortality. Pelvic ultrasonography by emergency physicians has been investigated as a diagnostic test for ectopic pregnancy. We present a meta-analysis of the use of emergency physician ultrasonography in the evaluation of patients at risk of ectopic pregnancy.

A structured search was performed of both MEDLINE and EMBASE. Inclusion criteria were that (1) the study reported original research on ED patients at risk for ectopic pregnancy; (2) an emergency physician performed and interpreted the initial pelvic ultrasonography; and (3) follow-up was conducted on all patients. Sensitivity was defined as the proportion of patients with ectopic pregnancy for which ED ultrasonography demonstrated no intrauterine pregnancy. A random-effects model was used to obtain summary test characteristics.

The initial search showed 576 publications, abstract review yielded 60 with potential relevance, and 10 studies were included. There was a total of 2,057 patients, of whom 152 (7.5%) had ectopic pregnancy. The pooled sensitivity estimate was 99.3% (95% confidence interval [CI] 96.6% to 100%), negative predictive value was 99.96% (95% CI 99.6% to 100%), and negative likelihood ratio was 0.08 (95% CI 0.025 to 0.25), all without significant heterogeneity.

The results of this meta-analysis suggest that in a wide variety of clinical settings, the use of bedside ultrasonography performed by emergency physicians as a diagnostic test for ectopic pregnancy provides excellent sensitivity and negative predictive value. Visualization of an intrauterine pregnancy by an emergency physician is generally sufficient to rule out ectopic pregnancy.

Nearly all emergency medicine residency programs provide some training in emergency physician-performed ultrasonography, but the extent of emergency physician-performed ultrasonography in community emergency departments (EDs) is not known. We seek to determine the state of ultrasonography in community EDs in terms of access to ultrasonography by other specialists and performance of ultrasonography by emergency physicians.

A 6-page survey that addressed access to ultrasonography performed by other specialists and emergency physician-performed ultrasonography was designed and pilot tested. A list of all US ED directors was obtained from the American College of Emergency Physicians. Twelve hundred of 5264 EDs were randomly selected to receive the anonymous survey, with responses tracked by separate postcard. There were 3 mailings from Fall 2003 to Spring 2004.

Overall response rate was 61% (684/1130). Respondents who self-reported as being academic with emergency medicine residents were excluded from further analysis (n=35). A sensitivity analysis (reported in parentheses) was performed on the key outcome question to adjust for response bias. As reported by ED directors, ultrasonography was available in the ED for use by emergency physicians at all times in 19% of EDs (12% to 28%), with an additional 15% (9% to 21%) reporting a machine available for use by emergency physicians in some capacity and 66% (51% to 80%) reporting that there was no access to a machine for emergency physician use. ED directors reported being requested or required to limit ultrasonography orders performed by radiology in 41% of EDs, with less timely access to radiology-performed ultrasonography in off hours. Of EDs with emergency physician-performed ultrasonography, the most common applications were Focused Assessment with Sonography for Trauma (FAST) examination (85%), code situation (72%), and check for pericardial effusion (67%). Of physicians performing ultrasonography, 16% stated they were currently requesting reimbursement (billing). The primary reason cited for not implementing emergency physician-performed ultrasonography was lack of emergency physician training. For the statement “emergency medicine residents now starting residency should be trained to perform and interpret focused bedside ultrasonography,” 84% of ED directors agreed, 14% were neutral, and less than 2% disagreed.

Community ED directors continue to report barriers to obtaining ultrasonography from consultants, especially in off hours. Nineteen percent of community ED directors report having a machine available for emergency physician use at all times; however, two thirds of EDs report no access to ultrasonography for emergency physician use. A majority of community ED directors support residency training in emergency physician-performed ultrasonography.

The variable accuracy of emergency department (ED) ultrasound described in the literature has limited its utility as the sole imaging modality in critical decision making. Although ultrasound accuracy is highly dependent upon the technical abilities of the operator and conditions unique to each patient, no previous study of ED ultrasound has included estimates of operator confidence. This prospective observational study explores the association between operator confidence and the accuracy of ED ultrasound. Ultrasound was not performed in our ED until a formal training module was instituted. Patients were enrolled prospectively for the first year following the training module if they underwent one of the following ultrasound studies: abdominal examination for intraperitoneal fluid, right upper quadrant examination for gallstones, renal examination for hydronephrosis, pelvic examination for intrauterine pregnancy, abdominal examination for aorta diameter > 3 cm, or cardiac examination for pericardial fluid. In addition, formal ultrasound, computed tomography, magnetic resonance imaging, or an invasive procedure was required as a “gold standard” for each patient. Operators recorded their interpretation of the ED ultrasound and rated their confidence with the analysis before the formal imaging study or procedure. Test performance characteristics for each examination type and for all studies together were determined. The association between operator confidence and accuracy was explored using logistic regression and by determining test performance characteristics with patients stratified by confidence value. A total of 276 ED ultrasound studies were included. There were no significant differences in accuracy between ED attendings and residents. Overall accuracy, sensitivity, specificity, LR+, and LR− were 90%, 92%, 86%, 6.8, and 0.09, respectively. With confidence scores of 9 or 10 (n = 113), these values improved to 96%, 99%, 90%, 9.6, and 0.01, respectively. Logistic regression revealed an association between confidence and ED ultrasound accuracy (p < 0.001). It is concluded that a significant association exists between operator confidence and the accuracy of ED ultrasound. High confidence values are associated with clinically useful test performance characteristics.

Focused bedside ultrasonography performed by emergency physicians is rapidly gaining acceptance in adult emergency medicine. This approach to ultrasound (US) is designed to answer a simple question, such as, “is there free fluid in the abdomen” using a limited, focused approach rather than a full diagnostic US examination. Common indications in adults include thoracoabdominal trauma, evaluation of first-trimester pregnancy, suspected abdominal aortic aneurysm, biliary disease, and renal colic. However, bedside US in pediatric emergency medicine is in its infancy, with few established indications. Few pediatric emergency physicians have extensive experience or training in bedside US; wider use of these techniques awaits the development of a cadre of physicians with such experience. Indications for emergency US in pediatrics are likely to differ somewhat from those in adults. It seems likely that focused assessment with sonography for trauma (FAST) examination will become more widely used as a diagnostic tool in pediatric trauma. Other possible indications for use in children may include the diagnosis of testicular torsion and intussusception and to assist vascular access and other procedures.

Ultrasound is the imaging study of choice for the detection of gallstones, but ultrasound through medical imaging departments (MI Sono) is not readily available on an immediate basis in many emergency departments (EDs). Several studies have shown that emergency physicians can perform ultrasound themselves (ED Sono) to rule out gallstones with acceptable accuracy after relatively brief training periods, but there have been no studies to date specifically addressing the effect of ED Sono of the gallbladder on quality and cost-effectiveness in the ED. In this study, we investigated measures of quality and cost-effectiveness in evaluating patients with suspected symptomatic cholelithiasis during three different years with distinctly different approaches to ultrasound availability. The study retrospectively identified a total of 418 patients who were admitted for cholecystectomy or for a complication of cholelithiasis within 6 months of an ED visit for possible biliary colic. The percentage of patients who had gallstones documented at the first ED visit improved from 28% in 1993, when there was limited availability of ultrasound through the Medical Imaging Department (MI Sono), to 56% in 1995, when MI Sono was readily available, to 70% in 1997, when both MI Sono and ED Sono were readily available (P <.001). There were also significant differences over the 3 years in the mean number of days from the first ED visit to documentation of gallstones (19.7 in 1993, 10.7 in 1995, 7.4 in 1997, P <.001); the mean number of return visits for possible biliary colic before documentation of gallstones (1.67 in 1993, 1.24 in 1995, and 1.25 in 1997, P <.001); and the incidence of complications of cholelithiasis in the interval between the first ED visit for possible biliary colic and the date of documentation of cholelithiasis (6.8% in 1993, 5.9% in 1995, 1.5% in 1997, P =.049). The number of MI Sonos ordered by emergency physicians per case of symptomatic cholelithiasis identified increased from 1.7 in 1993 to 2.5 in 1995 and dropped back to 1.7 in 1997, when 4.2 ED Sonos per study case were also done. The cost of ED Sonos was more than offset by savings in avoiding calling in ultrasound technicians after regular Medical Imaging Department hours. The indeterminate rate for ED Sonos was 18%. Excluding indeterminates, the sensitivity of ED Sono for detection of gallstones was 88.6% (95% CI 83.1-92.8%), the specificity 98.2% (95% CI 96.0-99.3%), and the accuracy 94.8% (95% CI 92.5-96.5%). We conclude that greater availability of MI Sono in the ED was associated with improved quality in the evaluation of patients with suspected symptomatic cholelithiasis but also with increased ultrasound costs. The availability of ED Sono in addition to readily available MI Sono was associated with further improved quality and decreased costs. The indeterminate rate for ED Sono was relatively high, but excluding indeterminates, the accuracy of ED Sono was comparable with published reports of MI Sono. (Am J Emerg Med 2001;19:260-269. Copyright © 2001 by W.B. Saunders Company)