Clinical Notes

Emergency Department Sonography by Emergency Physicians

DIETRICH JEHLE, MD, ERIC DAVIS, MD, TIM EVANS, MD, FRED HARCHELROAD, MD, MARCUS MARTIN, MD,

KIM ZAISER, MD, JEAN LUCID, MD

A retrospective study was conducted to examine whether emer- gency physicians can perform accurate ultrasonography that in- fluences the diagnosis and treatment of selected disorders in the emergency department (ED). The physicians acquired a moderate level of expertise in sonography using a series of practical dem- onstrations and lectures. Patients with symptoms suggestive of cardiac, gynecologic, biliary tract, and abdominal vascular dis- ease periodically underwent ED sonography. The initial interpre- tation was used as a diagnostic adjunct to subsequent therapy. The accuracy of positive sonographic findings was assessed by confirmatory testing, formal review, or confirmatory clinical course. Emergency physicians were able to diagnose correctly (1) the presence and approximate size of pericardial effusions, (2) the presence or absence of organized cardiac activity in patient with clinical electrical mechanical dissociation, (3) the presence or absence of intrauterine pregnancy in pregnant patients with lower abdominal/pelvic complaints, (4) the position of intrauter- ine devices in patients with suspected uterine perforation, (5) the presence of gallstones in patients with suspected biliary tract disease, and (6) the presence and size of abdominal aortic an- eurysms in patients with pulsatile masses or unexplained abdom- inal pain. It was concluded that reliable sonography which influ- ences diagnosis and therapy can be performed by emergency physicians and that sonography should become a standard pro- cedure in EDs.

Ultrasonography is a relatively new diagnostic pro- cedure that uses high-frequency sound waves to ex- amine the structure and function of internal organs.

From the Division of Emergency Medicine, Allegheny General Hospital, MCP-Allegheny Campus, Pittsburgh.

Manuscript received September 12, 1988; revision accepted De- cember 1, 1988.

Presented in part at the American College of Emergency Physi- cians Annual Meeting, San Francisco, November 1987.

Address reprint requests to Dr Jehle: Allegheny General Hospi- tal, 320 E North Ave, Pittsburgh, PA 15212.

Key Words:

0 1989 by W.B. Saunders Company.

0735-6757/89/0706-0010$5.00/0

This imaging technique uses a pulse echo process in which a piezoelectric element acts as both transducer and receiver. Short bursts of sound, each lasting 5 to 6 microseconds, are emitted from the transducer. Sound waves are reflected off of tissue interfaces and re- turned to the probe, which converts returning sound into electrical impulses that are transformed into a sonographic picture. Real-time sonography allows one to identify motion in anatomical structures by contin- uously updating the visual image projected onto the screen.

Recent advances in quality of imaging and portabil- ity have facilitated the application of ultr’asonography in the acute care setting, making real-time sonography an excellent screening procedure for various cardiac, gynecologic, biliary tract, and abdominal vascular dis- orders. Our hypothesis is that emergency physicians, with a moderate amount of training, can reliably per- form sonography which influences the diagnosis and treatment of selected disorders. In this preliminary study, we examined our initial experience with emer- gency department (ED) sonography and evaluated the accuracy of our positive findings.

METHODS

In this retrospective study, our attending staff and senior residents acquired a moderate level of expertise in sonography using a series of practical demonstra- tions and lectures with the Damon Scanmate (Damon Corporation, Needham Heights, MA) and IREX PS (Johnson & Johnson Ultrasound, Inc, Ramsey, NJ) systems. Real-time oscillating transducers with a me- dium focal zone of 3.0 to 3.5 MHz were used. Patients with symptoms of cardiac, gynecologic, biliary tract, or abdominal vascular disease periodically underwent ED sonography (Table 1). The initial interpretation was used as a diagnostic adjunct to guide further ther- apy. The accuracy of positive ED sonographic findings was assessed by confirmatory testing (computed to- mography [CT] or standard sonogram), formal review of the ED sonogram (still-frame), or confirmatory clin-

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TABLE 1. Indications for Emergency Sonography

Cardiac JVD, unexplained hypotension, pulsus paradox, enlarged

cardiac silhouette, or electrical alternans- R/O pericardial effusion

Clinical EMD-assess contractility and R/O effusion Gynecologic

Positive pregnancy test with pelvic pain or vaginal bleeding-rule in viable intrauterine pregnancy

Locate IUD when not seen on pelvic examination Biliary tract

RUQ pain-R/O gallstones Abdominal vascular

Pulsatile abdominal mass Unexplained abdominal pain I

R/O Aneurysm

ABBREVIATIONS: JVD, jugular venous distension; R/O rule out; IUD, intrauterine device.

ical course (progression of intrauterine pregnancy, outcome following electrical mechanical dissociation [EMDI, or results of diagnostic surgical procedures). The accuracy of negative gynecologic studies and neg- ative examinations in patients with EMD were as- sessed by confirmatory testing or confirmatory clinical course. Comprehensive follow-up for negative biliary tract, abdominal vascular, and cardiac (effusions) studies was not available. True-positives, false- positives, true-negatives, and false-negatives are re- ported.

Cardiac The cardiac applications extended to two sets of pa-

tients, those with suspected pericardial effusions and those with clinical EMD. Patients with jugular venous distension, unexplained hypotension, pulsus paradox, enlarged cardiac silhouette, or electrical alternans were suspected to have pericardial effusions. Clinical EMD was defined as narrow electrical complexes without measurable BP or clinical evidence of perfu- sion. The transducer was usually placed in the parasternal or apical position (fourth to fifth intercos- tal space), the subcostal position was used in patients with chronic obstructive pulmonary disease. Imaging was performed in the short axis, long axis, or horizon- tal four-chamber view. ’ Pericardial fluid confined pos- teriorly, without anterior lateral or apical spread (in the supine position), was defined as a small effusion. Effusions more evenly distributed anteriorly, laterally, and apically were classified as moderate in size. Large effusions were those that extended circumferentially around the heart with greater amounts distributed to the dependent regions.* The extent of organized car- diac activity and valve motion was assessed in patients with clinical EMD.

Gynecologic Patients in early pregnancy with pelvic pain or vag-

inal bleeding underwent ED sonography. Selected pa-

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tients with early pregnancies had B-KG titers drawn. If there was difficulty visualizing the pelvic structures due to an emptied bladder, the patient was orally or intravenously hydrated to fill the bladder and provide an acoustic window for viewing deeper structures. The transducer was placed in the suprapubic region with images obtained in both the longitudinal and trans- verse planes. In pregnant patients, anechoic structures within the uterus, with characteristic highly echogenic borders, were diagnosed as gestational sacs. When a small echogenic structure was visualized within the sac, a fetal pole was felt to be present.3 Real-time so- nography can subsequently demonstrate cardiac activ- ity in the fetal pole followed in 1 to 2 weeks by somatic motion.4 The presence of a gestational sac on ultra- sound was felt to be consistent with at least 5 to 6 weeks’ gestation, fetal pole with 6 to 7 weeks’, and cardiac activity with 7 to 8 weeks’.3 For practical pur- poses, the presence of an intrauterine pregnancy was used to rule out the presence of an ectopic pregnancy. In addition, sonography was used to document the po- sition of “lost” intrauterine devices, as well as fetal viability throughout pregnancy.

Wary Tract

Patients with symptoms suggestive of biliary tract disease (right upper quadrant [RUQ] pain) underwent ED sonography. The transducer was placed in the RUQ, and imaging thru the right lower rib spaces was performed as needed. Views were obtained in the su- pine and decubitus positions with deep inspiration. Additional imaging in the erect and belly-out positions was performed when supplemental views were re- quired. No patient preparation was possible, thus if the gall bladder was inadequately visualized the study was repeated after several hours of fasting. All pa- tients with positive findings on ED sonography (gall- stones or sludge) had corroborative follow-up. Echogenic densities within the gallbladder lumen with prominent posterior shadowing were diagnosed as gallstones.5 Echogenic structures in the gallbladder, without shadowing, which moved with gravity were also considered to be gallstones.6 Sludge refers to gravity-dependent echogenic bile.7 Confirmatory stud- ies on patients with negative findings were not per- formed in all cases; thus, we were unable to evaluate the accuracy of our negative biliary tract studies.

Abdominal Vascular Disorders

Patients with pulsatile abdominal masses or unex- plained abdominal pain underwent ED sonography of the abdominal aorta. Transverse scans in 1 to 2-cm steps to 3 cm below the umbilicus were followed by longitudinal scans. Aneurysm was defined as an aorta measuring >3 cm in the largest transverse diameter.5

JEHLE ET AL E ED SONOGRAPHY BY EMERGENCY PHYSICIANS

RESULTS

We found that Emergency Physicians were able to diagnose (1) the presence and approximate size of peri- cardial effusions, (2) the presence or absence of orga- nized cardiac activity in patients with clinical EMD, (3) the presence or absence of intrauterine pregnancy and fetal cardiac activity in pregnant patients with lower abdominal or pelvic complaints, (4) the position of intrauterine devices in patients with suspected uter- ine perforation, (5) the presence of gallstones in pa- tients with suspected biliary tract disease, and (6) the presence and size of abdominal aortic aneurysms in patients with pulsatile masses or unexplained abdom- inal pain. True-positives, false-positives, true- negatives, and false-negatives are presented in Ta- ble 2.

Cardiac

Three large clinically significant pericardial effu- sions were demonstrated by ED sonography. One pa- tient with cardiac tamponade, one with staphylococcal pericarditis (Fig l), and one postoperative intraperi- cardial hemorrhage were identified. Ultrasonography was used to guide emergent needle pericardiocentesis of two of the large pericardial effusions (one by an emergency physician and one by a cardiologist). In addition, four small- to moderate-sized nontraumatic pericardial effusions were identified that were fol- lowed conservatively. One patient with a stab wound to the anterior portion of the chest underwent cardiac imaging. No pericardial fluid was demonstrated by the initial ED sonogram or the formal study that followed. One of three patients in clinical EMD demonstrated good cardiac contractility (without significant effu- sion) on ED sonography; thus, resuscitation was con- tinued, with return of spontaneous pulses and respira- tions. No further pulses or respiration were achieved in those patients with poorly organized or absent car- diac activity.

TABLE 2. Accuracy of Emergency Department Sonography

Cardiac Gyneco- Vascular: logic: Biliary: ABD

Effusion EMD IUP Gallstones Aneurysms

True- positives 7 2 35 22 5

False- positives 0 0 0 0 0

True- negatives NA 1 4 NA NA

False- negatives NA 0 1 NA NA

Total Patients NA 3 40 48 NA

ABBREVIATIONS: IUP, intrauterine pregnancy; ABD, abdominal; NA, not available.

FIGURE 1. Large pericardial effusion, demonstrating large an- echoic space surrounding the heart, secondary to Staphylococcus

eureu~ pericarditis in a steroid-dependent asthmatic.

Gynecologic

Twenty of 40 pregnant patients studied in the ED demonstrated intrauterine pregnancies with good fetal cardiac activity (Fig 2). Fifteen patients demonstrated intrauterine gestation without visible fetal heart activ- ity (Fig 3). In five patients no gestational sac could be demonstrated. The presence of an intrauterine gesta- tion was confirmed in all 15 patients with gestational sacs without cardiac activity. Of the five patients with- out demonstrable gestational sacs on ED sonography (Fig 4), one had an ectopic pregnancy, two had missed abortions, one had an early intrauterine pregnancy

FIGURE 2. Intrauterine pregnancy with a large fetal pole and fetal cardiac activity.

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FIGURE 3. Intrauterine pregnancy with a gestational sac, demon- strating characteristic highly echogenie borders without a clear fetal pole or visible cardiac activity.

that was not visualized on initial formal sonography, and one had three gestational sacs on formal sonogra- phy, two of which involuted during early pregnancy. B-HCG titers ranged from 1,220 to 58,000 among those with early intrauterine pregnancies with visible gesta- tional sacs (n = 7) and ranged from 155 to 4,175 among those without demonstrable intrauterine gestational sacs (n = 4). One patient with a “lost” intrauterine device that was demonstrated on plain radiographs, without visualization of the string on examination, un- derwent ED sonography. Imaging displayed the intra- uterine device in the uterus without evidence of per- foration (Fig 5).

FIGURE 4. No gestational sac visualized in a pregnant patient.

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FIGURE 5. Intrauterine device correctly positioned in the uterine cavity.

Biliary Tract

Twenty-two of 48 patients with suspected biliary tract disease who were studied in the ED had positive ED sonograms; of those, 21 were found to have gall- stones (Fig 6) and one patient was noted to have sludge without clear evidence of stones. The presence of bil- nary tract disease with cholelithiasis was confirmed in all 22 patients with positive ED sonograms. Eighteen patients underwent early cholecystectomies, three pa- tients are being followed conservatively (poor surgical risk or declined surgery), and one patient had choleli- thiasis as an incidental finding (negative sonographic Murphy’s).

Abdominal Vascular Disorders

There were five patients with abdominal aortic an- eurysms diagnosed by ED sonography (Fig 7); of those, three aneurysms measured >5 cm in diameter. All three were confirmed by further studies or imme- diate surgery. The two smaller aneurysms were fol- lowed medically, and on formal review their measure- ments were verified to be in the 3- to S-cm range.

DISCDSSIDN

Sonography is an excellent procedure for diagnosing various cardiac, gynecologic, biliary tract, and abdom- inal vascular disorders. Our findings suggest that reli- able sonography of selected disorders from all of these groups can be performed by emergency physicians. Ultrasound is well suited for noninvasive imaging of internal organs. Sonography can identify structures that measure as small as 2 to 3 mm,5 and there are no known harmful effects at the energy levels used clinically.8-‘3

JEHLE ET AL I ED SONOGRAPHY BY EMERGENCY PHYSICIANS

FIGURE 6. Echogenic density (gallstone) with posterior acoustic shadowing in a patient with acute cholecystitis.

We found positive results of sonographic studies performed in the ED to have excellent reliability. The accuracy of negative results were more difficult to as- sess. We have complete follow-up data for our nega- tive gynecologic studies in pregnant patients and our negative examinations (absence of good organized car- diac contractility) in patients with EMD. Patients with

FIGURE 7. Leaking abdominal aortic aneurysm measuring 7.5 x 9.0 cm.

negative biliary or abdominal vascular study results were often followed conservatively witbout confirma- tory studies. In addition, comprehensive follow-up for normal cardiac studies (for pericardial fluid) was not available.

In order to perform the best imaging it is important to recognize some basic principles of ultrasonography. The propagation of sound is worst in gas, better in liquids, and best in solids. Air-containing structures conduct sound so poorly that they cannot be visual- ized with sonography. In addition, those structures that lie behind the air are poorly seen. Sound passes relatively undisturbed through homogeneous tissue. It is partially reflected as it passes from tissue of one density to tissue of another density. The strength of the returning echo is related to the difference in tissue densities and the angle the beam makes with the inter- face it strikes. Borders are more clearly demonstrated when the beam strikes at right angles to the surface.6

Echocardiography is the diagnostic procedure of choice in identifying pericardial effusions. l4 Effusions can result in rapid hemodynamic deterioration; as a result, the time to make the correct diagnosis and ini- tiate therapy is often limited. Patients who clinically appear to be in EMD can be separated into two groups. Those with electrical activity without visual evidence of organized cardiac activity seem to carry a poor prognosis similar to asystole. The patients with no obtainable BP but good cardiac contractility appear to have a better prognosis.15 Our experience has shown ED sonography to be helpful in several clinical situations. We concur with Mayron et al that ED car- diac imaging is indicated for penetrating wounds to the chest, nontraumatic unexplained hypotension in the setting of elevated central venous pressures, and non- perfusing cardiac dysrhythmias. l5 Blind pericardio- centesis without sonographic demonstra.tion of the ef- fusion should not be performed when ED sonography is available.

Ectopic pregnancies account for the majority of the first-trimester maternal deaths.i6 The frequency of ec- topic pregnancies varies greatly throughout the world between one in every 28 to 200 pregnancies.17 Misdi- agnosed ectopic pregnancies lead to significant patient morbidity and mortality. ‘s,19 Classically, ectopic preg- nancy presents with pelvic pain (>95%) and vaginal bleeding (55% to 74%) following a period of amenorrhea’7320*21; unfortunately, these complaints occur frequently during the first trimester of normal pregnancy .22 Proper assessment of patients with pel- vic pain and vaginal bleeding early in pregnancy is a difficult problem for emergency physicians.

The diagnosis of ectopic pregnancy is aided by the use of B-HCG titers and real-time sonography. The radioimmunoassay for B-HCG is almost always posi- tive in symptomatic ectopic pregnancies.“3 Because of

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the difficulty in diagnosing an ectopic pregnancy with sonography (only in 10% of ectopic pregnancies can a living extrauterine embryo be visualized),24 ultraso- nography is generally used to rule out an ectopic preg- nancy by demonstrating the presence of an intrauter- ine pregnancy .25,26 This is fairly accurate because si- multaneous intrauterine and extrauterine pregnancies occur only in one in 30,000 pregnancies.27 Sono- graphic findings that conclusively support the diagno- sis of intrauterine pregnancy include an intrauterine gestational sac with fetal cardiac activity or a clearly recognizable fetal pole.28 A pseudogestational sac is seen in 10% to 20% of ectopic pregnancies, and this may occasionally be confused with a gestational sac without a fetal pole.24,29,30

In a normal pregnancy, serial B-HCG titers should increase by 66% every 48 hours31 (peaking at 60 to 70 days’ gestation). 32 Patients with ectopic pregnancies produce B-HCG at a slower rate than those with nor- mal pregnancies. 33,34 However, 15% of intrauterine pregnancies fall below and 13% of extrauterine preg- nancies fall above these criteria.28 The B-HCG titer should exceed 6,500 mIU/ML by 42 days’ gestation in all normal intrauterine pregnancies. By this time, a gestational sac should be visualized in all healthy in- trauterine pregnancies. We found this to be the case in early pregnancies for which B-HCG titers were ob- tained. When the B-HCG titer exceeds 6,500 mIU/mL and an intrauterine sac is not present, a diagnosis of extrauterine pregnancy is likely.29 Hemodynamically stable patients with B-HCG titers ~6,500 mIU/mL without visible intrauterine gestation require further evaluation. The differential diagnosis in this setting in- cludes early intrauterine pregnancy, ectopic preg- nancy, blighted ovum (large empty gestational sac), molar pregnancy, or missed/incomplete abortion.28 Serial sonography and repeat titers are helpful in clar- ifying the diagnosis.

Acute cholecystitis results from obstruction of the cystic duct by gallstones in 95% of cases.35 Only 50% of patients with clinically suspected cholecystitis will actually have this disorder.36,37 Accurate assessment of the patient with suspected biliary tract disease is a perplexing problem in the ED. Because early surgical management of acute cholecystitis is now the treat- ment of choice, 38 diagnostic techniques that are rapid and dependable have been actively investigated.

Real-time ultrasonography is currently the preferred screening procedure for diagnosing cholecystitis.39-41 Recent studies have reported sensitivities and speci- ficities of >95%.42,43 The most sensitive sonographic criteria for acute cholecystitis are the demonstration of gallstones and localized tenderness over the gallblad- der (sonographic Murphy’s sign).5 Gallstones both ab- sorb and reflect sound waves; thus, the vast majority of stones appear as echogenic structures within the

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gallbladder lumen with prominent posterior acoustic shadowing. Nonshadowing echogenic structures in the gallbladder are calculi in only 50% of cases ,42 Gravity- dependent motion of an echogenic density helps sup- port the diagnosis of cholelithiasis. Echogenic bile or sludge does not necessarily imply intrinsic gallbladder pathology but suggests the presence of biliary stasis.5 We did not use more subtle findings such as wall thick- ness, pericholecystic fluid, or dilation of the common bile duct, which can also corroborate the diagnosis of acute cholecystitis.

Abdominal aortic aneurysm is a common and life- threatening manifestation of atherosclerotic vascular disease which presents most frequently as abdominal pain with or without a pulsatile abdominal mass in an elderly patient. Sonography has been shown to be quite accurate in diagnosing abdominal aneurysms and typically correlates within 3 mm with surgical findings.44 Ultrasonography is better than physical ex- amination (overestimates),45 lateral radiographs (overestimates),46 and aortography (underestimates)5 in measuring the size of an aortic aneurysm, and is of comparable accuracy to CT scanning.47 Disadvantages of sonography include difficulty imaging when there is a large amount of bowel gas, retained barium, or marked obesity.48

The most dangerous major complication of abdom- inal aortic aneurysms is rupture. It is important to measure the size of aneurysms accurately because the risk of rupture depends primarily on the diameter. An- eurysms that are followed conservatively increase in size by 0.26 to 0.4 cm per year.48’49 In an autopy se- ries, Darling et al found aneurysms 4 to 7 cm in diam- eter had a rupture rate of 25%; 7 to 10 cm, 45%; and >lO cm, 60%.50 Elective resection of asymptomatic aneurysms, due to a lower mortality, is indicated for low-risk patients with aneurysms that measure >5 cm in diameter.

CONCLUSIONS

We conclude that dependable sonography of se- lected disorders can be performed by emergency phy- sicians with a moderate amount of training. We found positive sonographic studies performed by emergermy physicians to be very reliable. Ultrasound can improve diagnostic and therapeutic decisions and should be- come a standard diagnostic procedure in all EDs.

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