A patient undergoes phlebectomy of the medial calf. On POD #7, there is a hyperechoic lesion around the area of the treatment. What is the likely source of the hypoechoic lesion?

The presence of a hypoechoic lesion around the treatment area one week post-phlebectomy can be attributed to a coagulum. In the context of a surgical procedure like phlebectomy, where veins are removed or treated, it's common for blood clotting to occur at the site of trauma. This coagulum typically forms as a natural response to tissue injury, where blood platelets aggregate and activate the clotting process.

The key factor that makes coagulum the likely source of the hypoechoic lesion is the timing of the ultrasound findings. At seven days post-operation, a hematoma, which is a localized collection of blood outside of blood vessels, typically may appear more complex on imaging, particularly if it’s breaking down or organizing. A seroma, which is a collection of clear fluid that can form after surgery, would usually appear anechoic or hypoechoic but would not typically present as a lesion in the same way a coagulum would at this time frame, especially in the context of the surgical site. Infection often presents with more complex features like irregular borders or increased echogenicity due to the presence of pus and surrounding inflammatory changes, making it less likely as the source in this scenario.

Thus, given the time