NEJM: Is ultrasound the stethoscope of the 21st century?
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An offshoot of the use of sonar in World War I, the first medical ultrasound image, taken of a human skull, came in 1947, followed 11 years later by the visualization of abdominal disease. At the end of the century it would once again be the battlefield that would transform the technology, with point-of-care ultrasound being originally developed for use in the battlefield and soon thereafter spreading quickly across numerous healthcare specialties, according to Christopher L. Moore, MD, and Joshua A. Copel, MD, of the departments of emergency medicine and obstetrics, gynecology and reproductive sciences at Yale University School of Medicine in New Haven, Conn.
Point-of-care ultrasound is performed and interpreted by clinicians at the bedside. “Point-of-care ultrasound images can be obtained nearly immediately, and the clinician can use real-time dynamic images (rather than images recorded by a sonographer and interpreted later), allowing findings to be directly correlated with the patient’s presenting signs and symptoms,” explained Moore and Copel.
These facets position ultrasound as a uniquely efficient modality for rapid diagnosis of conditions such as hypotension, chest pain or dyspnea in trauma situations (following a protocol of focused assessment with sonography for trauma, or FAST). Boasting accuracy between 90 and 98 percent in many emergency diagnoses, point-of-care ultrasound now shows potential for detecting pneumothorax and other conditions previously thought beyond the realm of ultrasonography.
Moreover, ultrasound provides static and dynamic guidance for a broad array of specialized procedures, including central and peripheral vascular access, thoracentesis, paracentesis, arthrocentesis, regional anesthesia, incision and drainage of abscesses, localization and removal of foreign bodies, lumbar puncture, biopsies and other procedures. Ultrasound has been established as one of the safest modalities, cited by the Agency for Healthcare Research and Quality as one of the 12 safest practices for reducing medical errors, the authors reported.
Finally, “Screening with ultrasonography is attractive because it is noninvasive and lacks ionizing radiation,” Moore and Copel noted. Although ultrasound has been used as a screening test for cardiovascular and gynecologic disease as well as for the abdominal aorta, the modality’s application in this area is less widespread and, according to the authors, requires further study.
“[T]he benefits of screening must be weighed against the harms, particularly false positive findings that lead to unnecessary testing, intervention, or both,” Moore and Copel argued. In at least several settings, the U.S. Preventive Services Task Force (USPSTF) agrees, having tentatively recommended against ultrasonography screening for carotid stenosis, peripheral vascular disease and ovarian cancer.
Still, the use of point-of-care ultrasonography is growing, especially among nonradiologists, while offering the potential as an accurate and less expensive substitute for some of the spikes seen in advanced imaging modalities. Meanwhile, the World Health Organization (WHO) has said that ultrasound, x-ray or a combination of both could meet two-thirds of the imaging needs of developing countries.
“However, indiscriminate use of ultrasonography could lead to further unnecessary testing, unnecessary interventions in the case of false positive findings, or inadequate investigation of false negative findings,” the authors cautioned. Moore and Copel concluded with a call for continued investigation into the technology’s capacity for screening, while echoing the American Institute of Ultrasound in Medicine’s portension of the “ultrasound stethoscope.”