The “Donut Sign”: when a thrombus envelops the fibrin sheath

Abstract

Catheter-related thrombosis is a common condition associated with various complications. In many cases, what appears to be catheter-related thrombosis is actually a fibrin sheath. Ultrasound examination serves as an effective diagnostic tool, particularly when a specific and intriguing ultrasound marker can aid in differentiation. Here, we present a clinical case that highlights this ultrasound marker, known as the “Donut Sign”.