Normal Chest X-ray Doesn’t Rule Out COVID-19
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APRIL 18, 2020 — Patients presenting at urgent care centers with symptoms that warrant suspicion of COVID-19 may have normal chest X-rays yet still be infected with SARS-CoV-2, according to findings of a study published online April 13 in the Journal of Urgent Care Medicine (JUCM).
“Providers ordering a chest X-ray in the outpatient setting should be aware that a patient with symptoms of COVID-19 may have a negative chest X-ray and should manage the patient based on their symptoms. Doctors should not be reassured by a negative chest X-ray,” said lead author Michael Weinstock, MD, an adjunct professor of emergency medicine at The Ohio State University College of Medicine in Columbus and a senior editor for JUCM.
Many early imaging studies of COVID-19 used CT to characterize the peculiarities of SARS-CoV-2 infection. However, CT is too costly and cumbersome to be part of a COVID-19 work-up in the urgent care setting. By contrast, chest X-ray is less sensitive, but widely available in urgent care centers and may help with COVID-19 diagnosis.
Therefore, to quantify how often chest X-ray reveals abnormalities consistent with COVID-19 in the urgent care setting, Weinstock and colleagues asked board-certified radiologists to re-read chest X-rays taken at more than 100 urgent care facilities in urban New York and New Jersey between March 9 and March 24.
Eleven radiologists re-read 47 to 100 chest x-rays each, totaling 636 images, from patients who were eventually confirmed to have symptomatic COVID-19. The radiologists who had initially read the films did not know the diagnostic status of the patients because of limited testing in March. The radiologists were instructed to disregard the initial interpretations and to classify each film as indicating normal, mild, moderate, or severe disease.
Of the 636 X-rayed patients, 363 (57.1%) were male. They ranged in age from 18 to 90 years.
Upon second inspection, 371 (58.3%) of the 636 chest X-rays were classified as normal. Of the 265 (41.7%) re-read as abnormal, 195 were classified as mild disease, 65 as moderate, and 5 as severe. That is, 89% (566 of 636) of the scans were re-read as normal or mildly abnormal.
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The radiologists who initially read the films had classified a greater percentage as normal — 468 (73.6%) of the 636. The second scrutiny reclassified 97 of the films initially deemed normal as abnormal.
Weinstock doesn’t think that the foreknowledge of diagnosis altered the second looks. “This gave the study more power, because even [though] the radiologists knew the diagnosis, still 58% of the X-rays came back re-read as normal or only mildly abnormal,” he told Medscape Medical News.
On the chest X-rays, interstitial changes were most common, seen in 151 (23.7%), and ground glass opacities predominated in 120 (18.9%). The abnormalities were in the lower lobe in 215 (33.8%) of the images, bilateral in 133 (20.9%), and multifocal in 154 (24.2%).
Although chest X-ray may not rule out COVID-19, it can help rule out other conditions, such as bacterial pneumonia, pneumothorax, or cancer, Weinstock said. And it’s helpful in troubleshooting a rough road ahead, combined with carefully observing patients.
Sometimes “we see multifocal infiltrates in areas of both lungs that show more severe disease than we’d expect just from looking at the patients. We wouldn’t have admitted them to the hospital because the oxygen level is still okay, but the X-ray result is more suggestive they actually have the disease,” Weinstock said.
Saurabh Jha, MBBS, MRCS, associate professor of radiology at the Hospital of the University of Pennsylvania in Philadelphia, agrees that chest X-rays are imperfect, but still useful. “They aren’t good at identifying what is causing the patient’s symptoms because they’re both insensitive and nonspecific,” he said. “But they’re reasonably good at determining how bad the disease process is. So long as physicians realize that a negative chest X-ray isn’t a passport to abandon social distancing and isolation, I’d encourage its use.”
In addition to CT and chest X-rays, physicians in Italy are using handheld wireless ultrasound devices to help triage patients in the emergency department. They say the technology helps distinguish patients who have COVID-19-related pneumonia and need to be hospitalized from those who can safely quarantine at home. Ultrasound can indicate interstitial pneumonia in some cases in which the chest X-ray is negative.
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However, the writing committee of the Fleischner Society’s Multinational Consensus Statement on the Role of Chest Imaging in Patient Management during the COVID-19 Pandemic, released April 7, does not yet have sufficient direct experience or published data to comment on the use of ultrasound, said lead author Geoffrey D. Rubin, from the Duke University School of Medicine, Durham, North Carolina.
But these are different times, so he conceded that ultrasound use might be of benefit. Considering “the extent to which critical resources such as hospitals beds, PPE, and ED capacity are overwhelmed by COVID-19, unconventional uses of available technologies may be effective in making an unmanageable situation into a manageable one. I believe that handheld ultrasound may fall in this category,” Rubin said.
Weinstock and colleagues note several limitations of their study, including that it was retrospective and observational, and films were from patients at different stages of infection. In another study underway, the researchers are correlating radiological findings to the patients’ clinical signs, medical history, and demographic characteristics.
Medscape Medical News
Sources
J Urgent Care Med. Published online April 13, 2020 (E-pub ahead of print).
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