Plain radiography remains the imaging study of choice for most applications in the upper extremity. The upper extremity is divided into three sections: the shoulder, the elbow and forearm, and the wrist and hand. Similar to the shoulder, the most common use of elbow and forearm plain radiography is in the setting of acute trauma. As with the rest of the upper extremity, the major indication for imaging of the wrist and hand is in the setting of acute trauma. It is one of the most difficult areas to differentiate between soft tissue and skeletal injury on history and physical examination alone. Imaging is necessary even with obvious fractures because the extent of the fracture, displacement, angulation, and articular involvement are important to determine if the patient needs closed reduction in the ED or immediate orthopedic referral for possible open reduction and surgical fixation.

Lower extremity injuries are frequently encountered in ED and urgent care settings. Lower extremity radiography is useful for the diagnosis of fractures and dislocations of the hip, knee, foot, and ankle, as well as demonstrating pathology of the femur, tibia, and fibula. Plain radiography is helpful in evaluating fractures of the lower extremity bones, as well as masses and malignancies, including pathological fractures. Information obtained from plain radiographs may be limited by several factors. Information obtained from plain radiographs may be limited by several factors such as quality of the technique employed. Penetration of the image and proper patient positioning are crucial to obtaining useful images. As with any radiographic imaging, one must have sufficient knowledge of the normal anatomy to be able to recognize pathology. This includes the ability to distinguish normal variants from true pathology.

The chest radiograph (CXR) is the most commonly ordered plain film in emergency medicine and has correspondingly broad indications. Patients who complain of chest pain have a broad differential diagnosis, and CXR is one of the first screening tests to be applied in chest pain complaints. CXR is useful to diagnose or identify primary cardiac and pulmonary pathology, abnormal pleural processes, thoracic aortic dilation, aspirated foreign bodies, and thoracic trauma. Pleural processes such as pleural thickening, pneumothorax, hemothorax, and pleural effusions are evident on CXR. CXR is the first radiologic screening test for thoracic aneurysm. Skeletal injuries, including rib, scapular, clavicular, shoulder, and sternal fractures and dislocations, can be seen on CXR. CXR identifies lung masses, pleural lesions, air-space disease, and hilar masses. However, the quality of these lesions is better delineated by CT. A consistent approach to the CXR improves detection of pathology.

By far, the commonest indication for abdominal plain film radiography is abdominal pain. In examining an abdominal plain film, it is often helpful to have a systematic approach because many findings are subtle and easily overlooked. An upright chest or abdominal radiograph should include the diaphragms, which should be checked for abnormal subphrenic radiolucencies. Splenic enlargement due to trauma or medical disease may be suggested by displacement of the splenic flexure, gastric bubble, or left kidney. Linear radiolucencies in the liver indicate gas in the biliary or portal systems. This finding associated with small bowel obstruction suggests gallstone ileus. A variety of abnormal radio densities can be encountered on plain films. Most are due to abnormal calcifications within the soft tissues, although they can also be caused by foreign bodies, surgical clips, pills, or intramuscular injections. Plain films are rarely indicated in the evaluation of gastrointestinal hemorrhage or gastroenteritis.

EDs each year with potential cervical spine (C-spine) injury, prompting approximately 800,000 C-spine radiographs. C-spine or neck radiographs are often useful in evaluating non-traumatic conditions commonly presenting to the ED. C-spine injuries are present in only 2% to 6% of blunt trauma victims and in even fewer non-traumatic ED patients, but the potential for catastrophic outcomes of missed C-spine injuries has led to a high index of suspicion by emergency physicians. C-spine injury is relatively uncommon in the pediatric population; however, rates of mortality and neurological damage are alarmingly high. The pitfall of pediatric C-spine radiography lies in the condition known as spinal cord injury without radiographic abnormality. A growing body of evidence and an increasing amount of authorities are now advocating a shift to computed tomography (CT)-based screening of blunt trauma victims for C-spine injury. CT has been shown to be up to 100% sensitive in multiple studies.

Radiographic evaluation of the pelvis and spine often starts with plain radiographs, most commonly ordered after a traumatic injury. Patients with non-traumatic back pain do not routinely need radiographs. Indications for plain films in these patients include age older than 55 years, or back pain lasting longer than 4 weeks. Thoracolumbar radiology is capable of diagnosing fractures of the vertebral bodies, such as burst or compression fractures, or transverse fractures due to distraction injuries. Ligamentous injuries can be identified by widening or rotation of the spinous processes, or by dislocation of one vertebral body relative to another. Osteomyelitis, tumors, and Paget disease may be diagnosed if thoracolumbar involvement is present. In the thoracolumbar spine, a burst fracture may be mistaken for a less serious compression fracture. Computed tomography (CT) of the abdomen and pelvis, performed on many trauma patients, may be more accurate in diagnosing injuries of the thoracolumbar spine.

Plain extremity radiographs are indicated in pediatric patients with significant mechanism of injury, pain, limitation of use or motion, or physical exam evidence of deformity, swelling, or tenderness. The joint above and below the site of injury should be examined, and radiographs of adjacent joints should be obtained when indicated. Pediatric extremities consist of growing bones and ossifications centers, with wide variability in normal-appearing bones based on age. As the physic itself is radiolucent, physeal fractures are not always evident on initial plain radiographs. Minimum views of the extremity should include anteroposterior (AP) and lateral. Negative initial plain radiographs do not exclude a Salter-Harris type 1 physeal fracture. If a pediatric patient has negative films but significant swelling or point tenderness along the physic of a bone, a physeal fracture and splint can be assumed accordingly. The incidence of sprains and dislocations are less common in children than in adults.

Plain film radiographs of the chest ordered from the ED are indicated in stable patients to provide contributory information in the diagnostic process of health complaints potentially involving the chest. The radiographic findings on plain film chest serve as a useful screening measure to confirm or rule out the presence of various chest conditions. Interpreting plain film radiographs is similar to identifying an object by examining only the shadow of the object. Unlike advanced imaging methods (CT, ultrasound, MRI), plain film radiographic abnormalities are often subtle. Plain film radiograph can be utilized to diagnose pneumonia, atelectasis, pulmonary edema, lung abscess, tuberculosis etc., in the lungs, and cardiomegaly, congestive heart failure, congenital heart disease etc., in the heart. Plain radiographs are also used to diagnose aortic dissection and aortoesophageal syndrome, pneumomediastinum, thymus enlargement, and fractures such as clavicle fractures and rib fractures.

Plain film radiographs of the pediatric abdomen ordered from the ED are indicated in stable patients to provide contributory information in the diagnostic process of abdominal health complaints. The criteria for distinguishing a bowel obstruction from an ileus include roughly four findings: gas distribution, bowel distention, air fluid levels and orderliness. The differential diagnosis of a bowel obstruction can be remembered with the mnemonic A-A-I-I-M-M, (adhesions, appendicitis, incarcerated hernia, intussusception, malrotation (with midgut volvulus), and Meckel's diverticulum (with a volvulus or intussusception)). A sigmoid occurs more often in elderly patients, whereas a midgut volvulus is a true surgical emergency. Plain film radiographs have a limited role in diagnosing appendicitis. It can be highly diagnostic of intussusception. Abdominal foreign bodies are usually not visible on plain film radiographs, with the exception of metallic and calcific foreign bodies. Uric acid and most calcium oxalate stone are not radiopaque on plain film radiographs.

Complete skeletal survey plain radiographs are essential in the evaluation of suspected child abuse, particularly in infants and toddlers. Extracranial abnormalities are detected in 30% to 70% of abused children with head injuries. Shaken baby syndrome is described as subdural hematoma, retinal hemorrhages, and long bone fractures with minimal external signs of trauma. Due to the close association of intracranial injuries with fractures in nonaccidental trauma, both CT of the head and complete bone survey radiographs should be minimal standard imaging in any suspected child abuse case. Fractures suggestive for nonaccidental trauma can be categorized based on specificity for abuse. Subtle injuries may be missed on initial acute skeletal survey. Delayed repeated skeletal radiographs may be needed. Negative skull radiographs as part of the skeletal survey do not obviate the need for obtaining CT of the brain to investigate for intracranial bleeding or injury in suspected abuse cases.

The elderly have some indications for plain film radiography that are specifically determined by their age group. Imaging of the pelvis is most commonly prompted by pain and/or trauma. In addition to identification of fractures, emergency physicians should look for neoplastic lesions and degenerative changes of the hip joints or sacroiliac joints. Rheumatologic conditions are increasingly common with age. Plain radiology in the evaluation of non bony abdominal pathology has the same limitations in the elderly as it does for other adults, with the consequence that CT is often the imaging modality of choice. Most of the limitations of plain radiography in the elderly are the same as those for adults. Radiographs are limited by the patient's ability to cooperate with the exam. This chapter presents clinical images depicting radiographic findings and pathology that clinicians should be familiar with in the elderly patient.

Nothing has generated as much change in emergency medicine in the past 15 years as the introduction of bedside ultrasound. This chapter presents an overview of the pathway for physicians to become skilled in the use of bedside sonography and the elements required to implement a bedside ultrasound program. The whole idea of ultrasound is to create interpretable pictures of internal anatomy, so that the primary goal is to select a machine that makes the best pictures possible. The most widely used training guidelines in emergency bedside ultrasound were published by the American College of Emergency Physicians (ACEP) in 2001; they outline the type and amount of experience a physician needs to be considered competent in limited emergency ultrasound. A well-structured ultrasound program should have training and usage policies, and should be set up with cooperation and approval of the hospital governing body.

The fundamental principal of diagnostic ultrasound relies on the transmission of sound into the patient's body and reception of reflected sound, which is then displayed as data for interpretation. As with the time gain control (TGC) control, the gain control allows a manual adjustment of the intensity of the returning echoes. The unit of measure is the decibel and may be displayed on the screen as "db" or as a numerical value. The depth control allows the operator to manually adjust the field of view, determining how much of the information deep to the probe is displayed. This chapter presents an introduction to the modes of Doppler available on common ED systems. The sonographer must select a transducer for each exam with consideration of the patient's body habitus and the anatomy to be visualized. Image artifacts may result from transducer design, anatomical interfaces, and ultrasound beam properties.

Biliary ultrasound is part of any complete abdominal ultrasound and limited right upper quadrant ultrasound. It is more difficult to perform abdominal ultrasound on obese patients. This statement is particularly true with regard to the liver, gallbladder, and associated structures. The limitations of ultrasound in the right upper quadrant are few. Since ultrasound creates 2D images of 3D structures, the experience level of the sonologist is very important. It should be noted that ultrasound is not the most accurate imaging study for cholecystitis. The biliary system is made up of the gallbladder, along with the intra- and extrahepatic biliary ducts. The intrahepatic ducts form in the subsegments of the liver and course toward the porta hepatis where they form the common hepatic duct (CHD). The intrahepatic ducts are more difficult to evaluate because they are normally very narrow.

The use of ultrasound in acute trauma has increased dramatically over the past 30 years. The oldest and most established indication for ultrasound in the ED is blunt abdominal trauma. The focused assessment with sonography in trauma (FAST) exam has become a standard imaging modality in the setting of acute trauma and is incorporated into the American College of Surgeons' Advanced Trauma Life Support guidelines. In the setting of acute cranial trauma, ultrasound may be useful in the detection of elevated intracranial pressure. Thoracoabdominal sonography can be limited by patient body habitus. In the abdomen, bowel gas, subcutaneous emphysema, pneumoperitoneum, and rib shadows can hinder evaluation of deeper structures. Evaluation of the heart and thorax can be limited by rib shadows, emphysematous lungs, or subcutaneous emphysema. Imaging the orbit should be done with care; no pressure should be applied to the eye, which causes retinal detachment or a ruptured globe.

Deep venous thrombosis (DVT) is an extremely common disorder, estimated to occur in approximately 2 million Americans per year. Ultrasonography of an extremity to check for the presence of a DVT is a commonly requested examination. A lower extremity venous ultrasound consists of imaging the common femoral vein (CFV) beginning at its confluence with the greater saphenous vein in the inguinal region and continuing to the superficial femoral vein until the distal thigh. Examination of the popliteal vein (PV) is performed by slight flexion of the knee and external rotation of the hip. Lack of vein compressibility is the main indicator of a thrombus. The use of bedside sonography in patients with a painful swollen extremity is helpful in diagnosing a deep venous thrombosis. The most important component of this exam is the determination of the compressibility of the veins.

Cardiac ultrasound, or echocardiography, can be one of the most powerful noninvasive diagnostic tools available to the clinician in emergency situations involving critically ill or potentially critically ill patients. It is important to consider the positioning of the examiner and scanner relative to the patient. When a cardiologist or sonographer performs an echo, it is typically done from the left side of the patient, with the probe held in the examiner's left hand. It is also important to understand the imaging conventions used in cardiology compared to other ultrasound. Probe selection and equipment are important in obtaining quality images. Patient body habitus and comorbid conditions may limit imaging. The most common echo pitfall is that physiological pericardial fluid and/or epicardial fat may be misinterpreted as a pericardial effusion. Artifacts are common in ultrasound and may be seen in cardiac echo.

The principal indication for renal ultrasound is in the diagnosis of ureteral calculi, which, if they cause obstruction, will give rise to unilateral hydronephrosis. Less commonly, retroperitoneal processes or pelvic pathology originating in the prostate, ovaries, or urethra may give rise to bilateral hydronephrosis. Patients being evaluated for hydronephrosis should be adequately hydrated, but not overhydrated. Renal ultrasonography may be limited by technical challenges in obtaining the images or be due to inherent characteristics of the test itself. False-negative exams for hydronephrosis occur when there is actual obstruction without calyceal dilation, which is rare unless the kidney was already nonfunctioning. The diagnosis of renal tumors is not within the standard purview of the emergency ultrasonographer. Ultrasound is limited in the identification of renal masses by both their size and sonographic appearance. Expertise and sonographic skill play an important role in accurate identification of renal masses.

The primary indication for emergent ultrasonography of the aorta is to identify an abdominal aortic aneurysm (AAA). AAAs develop slowly and may be asymptomatic or present with life threatening rupture. AAA rupture accounts for more than 10,000 deaths per year in the United States. When ruptured or leaking AAA is suspected, ultrasound has many appealing qualities. Particularly for the hemodynamically unstable patient, bedside ultrasonography offers a prompt, accurate diagnosis. Although ultrasound is an excellent modality for identifying AAA, it is not effective in identifying whether rupture or leaking has occurred. The decision that an AAA is ruptured is typically based on ultrasound findings of the presence of an aneurysm as well the patient's clinical presentation. The presence of an obese body habitus or bowel gas may lead to poor quality ultrasound imaging and make accurate assessment of AAA difficult.

Urinalysis is critical in evaluating and treating patients with urinary tract infections or complex urosepsis. Ultrasound guidance for suprapubic bladder catheterization shows improved success rates, decreased number of attempts, and decreased complications. Ultrasound guidance for placement of central venous catheters (CVCs) is one of the most important uses of ultrasound in the clinical setting. Undetected foreign bodies during initial ED visits may lead to complications, including inflammatory reaction, infection, delayed wound healing, poor cosmetic outcome, and, less often, life-threatening illness. Therapeutic thoracentesis is performed when patients are symptomatic due to an effusion. Pneumothorax is the major complication associated with thoracentesis. Lumbar puncture (LP) is one of the most frequently performed procedures in the acute care setting. The amount of peritoneal fluid in patients requiring therapeutic paracentesis may be large enough that ultrasound is not necessary. Unrecognized pericardial tamponade is one of the most quickly fatal pathological entities in medicine.

Abdominal-pelvic ultrasounds ordered or performed in the ED are used to diagnose life-threatening obstetrical or gynecological diseases that may require emergent surgery. Nonpregnant patients with lower abdominal pain, pelvic pain, or tenderness on bimanual examination are also candidates for a pelvic ultrasound in order to rule out ovarian torsion or tubo-ovarian abscess. Pelvic ultrasound is also capable of helping guide the emergency physician in the management of other non-emergent obstetrical/gynecological disease processes, such as incarcerated uterus, abnormal intrauterine pregnancies, no definitive pregnancies, and ruptured ovarian cysts. This chapter includes gynecological normal images of the uterus, ovaries, and bladder in sagital and coronal planes. It also presents obstetrical normal images of the uterus and ovaries in sagital and coronal planes, and pathological images of the uterus, ovaries, and adnexa in sagital, coronal, and some oblique planes.

Ultrasound has long been an integral part of the ophthalmologist's examination of the eye and orbit. The use of ocular ultrasound was first published in 1956 and has since come to be used extensively with A-scan, B-scan, Doppler, and, more recently, 3D approaches. Both axial and longitudinal approaches are commonly employed in ED ultrasound of the eye and orbit. Due to the emphasis on recognition of acute life-threatening conditions in the ED, the application of ocular ultrasound most widely studied in the emergency medicine literature is in the evaluation of increased intracranial pressure by evaluation of optic nerve sheath diameter. Ultrasound easily allows identification of lens dislocation, vitreous hemorrhage, and globe rupture, among other traumatic conditions. ED ultrasound may also prove to be useful in the evaluation of optic neuritis. Ocular ultrasound is a relatively new ED imaging modality that is rapidly gaining acceptance among emergency clinicians.

Testicular ultrasound has emerged as the imaging modality of choice for any patient with testicular complaints. The primary indication for testicular ultrasound is acute scrotal or testicular pain. The most common etiologies of acute scrotal pain are epididymitis, orchitis, testicular torsion, and scrotal trauma. Complications of testicular torsion include testicular infarction and testicular atrophy, both of which can be diagnosed by ultrasound. Testicular ultrasound is both the initial imaging modality of choice, as well as the preferred diagnostic method for follow up of patients with acute, recurrent, or chronic testicular/scrotal symptoms. Pitfalls in testicular ultrasound may be divided into several categories. The most critical scanning pitfall relates to a misunderstanding of the skill and knowledge required for using color Doppler imaging (CDI), power Doppler imaging (PDI), or spectral Doppler imaging (SDI). The testicular ultrasound should include transverse, and inferior pole views, both in gray scale and using CDI and SDI.

Abdominal ultrasound has become an extremely useful imaging modality in emergency medicine. Acute appendicitis can be diagnosed with ultrasound and is the preferred initial imaging modality by some clinicians for certain populations, such as in pregnant patients, to avoid ionizing radiation. Ultrasound can be a useful imaging modality for evaluation of abdominal wall hernias, such as ventral wall hernias, incisional hernias, spigelian hernias, femoral hernias, and inguinal hernias. The diseases of the GI tract that can be detected by ultrasound, but may be more appropriately detected by CT scan, are diverticulitis, bowel obstruction, and Crohn disease. Ultrasound imaging of the pancreas is not routinely sought in the ED, but rather more often done on an inpatient or outpatient basis for ultrasound-guided procedures. Ultrasound can be a challenging modality in obese patients and thus has some limitation in the evaluation of various intraabdominal diseases, such as appendicitis.

This chapter discusses the techniques, pathology, and potential pitfalls involved in the use of musculoskeletal ultrasound in the emergency department (ED). It reviews the sonography features of tendons, muscles, bone, joints, ligaments and nerves, and specific imaging techniques. Although fractures are typically diagnosed in the ED by radiography, there is a role for ultrasound in diagnosing fractures. Sonography is very accurate in detecting fractures of the humerus, midshaft femur, radius/ulna, and tibia/fibula. To evaluate the humerus, the transducer should be placed over the distal humerus anteriorly. Imaging of the femur should begin at the distal femur by placing the probe superior to the patella over the thigh laterally. Rib fractures are often difficult to detect on radiographs. In the case of a suspected rib fracture, ultrasound can be used to confirm the diagnosis. Sonography also has a role in identifying and assisting with the aspiration of joint effusions.