Researchers at Rutgers Robert Wood Johnson Medical School are reporting the first instance of COVID-19 triggering a rare recurrence of potentially serious blood clots in people's arms. The discovery, published in the journal Viruses, improves the understanding of how inflammation caused by COVID-19 can lead to upper extremity blood clots and how best to treat them. The case study is part of a larger Rutgers study of 1,000 hospitalized patients diagnosed with COVID-19 who were admitted and discharged between March and May 2020.

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While there have been reports of lower extremity deep vein thrombosis following COVID-19, this is the first study in which COVID-19 triggered a recurrence in the upper arm of an active 85-year-old man who had a prior diagnosis of upper extremity blood clots.

"The patient presented to his primary care physician with complaints of swelling in his left arm and was sent to the hospital for further management where he was diagnosed with an upper arm blood clot and an asymptomatic COVID-19 infection," said Payal Parikh, an assistant professor of medicine at Rutgers Robert Wood Johnson Medical School, who led the study along with Martin Blaser, director of the Center for Advanced Biotechnology and Medicine and a professor at Rutgers Robert Wood Johnson Medical School. "While his oxygen levels were not diminished, he was hospitalized for the management of the upper extremity deep vein blood clot. Often, blood clots are preceded by chronic inflammatory conditions exacerbated by immobility, and rarely do they occur in patients who are otherwise healthy and active at baseline."

Most cases of deep vein thrombosis occur in the legs. Only about 10% of blood clots occur in the arms and of those cases only 9% recur.

"This is of concern since in 30% of these patients, the blood clot can travel to the lung and be possibly fatal," said Parikh. "Other disabling complications include persistent swelling, pain and arm fatigue."

The study suggests that clinicians should consider testing for deep vein thrombosis and COVID-19 in patients who present with complaints of unexplained swelling. People who test positive for COVID-19 should seek medical attention if they have declining oxygen levels, shortness of breath and any unexplained swelling.

"If you have been previously diagnosed with deep vein thrombosis or have chronic medical illness that predisposes you to blood clots, you have a higher risk for recurrence of a deep vein thrombus in the setting of a COVID-19 infection and thus, should be vigilant," said Parikh.