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Portable ultrasound scans were more sensitive than x-rays at the preliminary detection of atypical pneumonia in patients who may have COVID-19, a researcher reported.

In a study of possible COVID-19 patients who presented to the emergency department (ED), ultrasound sensitivity was 97.6% (95% CI 91.6-99.7) versus 69.9% (95% CI 58.8-79.5) for x-ray, reported Ryan C. Gibbons, MD, of the Lewis Katz School of Medicine at Temple University in Philadelphia, in a presentation at the virtual American College of Emergency Physicians meeting.

Gibbons urged an "ultrasound first" approach to screening. "It's a valuable tool to quickly separate the lower-risk from higher-risk patients and move those lower-risk patients out," he told MedPage Today following his online presentation.

Ultrasound scans, which can easily be performed at bedside with handheld devices, are also more convenient than x-rays, Gibbons said. Physicians use "a handheld probe that plugs into an iPad. You can be in and out of a room in under a few minutes and sanitization is very quick. And we're not transporting a patient to and from x-ray or having to wait for a portable x-ray machine," he said.

Physicians have spent months been trying to figure out the best approach to initial imaging in patients who may have COVID-19. In March, the use of ultrasound in all patients who present with flu-like symptoms.

Gibbons and colleagues prospectively tracked 143 consecutive potential COVID-19 patients who presented at an ED. Each patient was screened via handheld ultrasound and portable x-ray. Those at high-risk, and those who showed abnormal findings, were sent for CT scans.

Physicians interpreted 99 ultrasound scans and 73 x-rays as positive. The CT scans confirmed that 75% (95% CI 66.0-83.2) of these patients had atypical pneumonia. Gibbons said this number is especially high because the patients were tracked during a period of widespread infection.

Specificity was 33.3% (95% CI 16.5-54.0) for ultrasound and 44.4% (95% CI 25.5-64.7) for x-ray.

"Our initial hypothesis based on previous data is that ultrasound is more sensitive, and that's what we found," Gibbons said. While specificity is "sacrificed," ultrasound positive findings serve as warning signs that trigger further testing for confirmation, he said.

Gibbons said that at his hospital, patients who may have COVID-19 are now routinely screened via ultrasound scans instead of x-rays. Patients with negative results typically go home, while those with positive scans are sent for CT scans and usually admitted, he said.

Another Philadelphia physician said the study findings are valid and mirror the findings of his own research – – into the accuracy of ultrasound versus x-ray screening for atypical pneumonia in COVID-19.

"Common findings with ultrasound in COVID-19 patients include thickened irregular pleural lines, vertical artifact (B-lines) which represent inflammatory changes in the lung, and absence of normal horizontal artifacts (A-lines)," said Laith R. Sultan, MD, MPH, of the department of radiology at the University of Pennsylvania.

In contrast, x-ray findings "are more limited to opacities seen in the affected area," he said, and x-rays may not detect signs earlier in the inflammatory process that can appear via ultrasound scans.

However, Sultan cautioned that "findings from COVID-19 pneumonia can have similarities with findings from other viral causes of pneumonia. In our article, we showed that some findings are very specific to COVID-19, e.g., the skip area seen in pleural lines and B-lines and absence of blood flow on Doppler. These findings can be related to the acute inflammatory process that take place in COVID-19."

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