ABSTRACT
Background: COVID-19 is caused by SARS-CoV-2 infection, and cytokine storm and microthrombus formation affect the severity of the disease, which is often complicated by venous thrombosis due to a systemic hypercoagulable state. On the other hand, indwelling peripheral venous catheters can cause catheter-related bloodstream infections and venous thrombus formation, albeit less frequently. Case presentation: A 53-year-old man was admitted to the hospital with severe COVID-19. He had bilateral pneumonia and required ventilator management but recovered after steroid and anticoagulation. On the 26th day after onset, redness, swelling, and pain developed around the insertion site of the catheter placed in the cephalic vein of the left forearm. Vascular ultrasonography revealed a thrombus in this vein accompanied by inflammation in the surrounding tissues. Catheter-related bloodstream infection was suspected and vancomycin was administered; however, blood cultures were negative, leading to the diagnosis of non-infectious superficial thrombophlebitis. The skin findings improved after removal of the peripheral venous catheter. Conclusions: This case suggested that catheter placement in peripheral veins during COVID-19 treatment increases the risk of thrombus formation. Although anticoagulant therapy is able to control the systemic hypercoagulable state caused by COVID-19, indwelling catheters can induce a local hypercoagulable state, leading to superficial thrombophlebitis.