Unilateral Arm Swelling on Apixaban: Central Venous Thrombosis Missed by Point-of-Care Ultrasound

A 57-year-old man with metastatic colorectal cancer, a left internal jugular port, and reported apixaban use presented to the emergency department with worsening unilateral left upper-extremity swelling. Overnight point-of-care ultrasound did not identify a definite deep venous thrombosis (DVT), and he was discharged with next-morning formal imaging because formal vascular ultrasound was unavailable overnight. Formal imaging later that same day showed axillary thrombosis, and contrast CT of the neck and chest revealed bilateral internal jugular thrombosis, chronic left brachiocephalic thrombosis, suspected acute-on-chronic central venous thrombosis of the left upper extremity, and possible extension into the right transverse sinus. Venography and intravascular ultrasound later demonstrated near-occlusive thrombus involving the left axillary, subclavian, and brachiocephalic veins with severe underlying brachiocephalic stenosis. Aspiration thrombectomy and venoplasty improved central venous outflow. This case illustrates that persistent unilateral arm swelling in a high-risk oncology patient may reflect central venous thrombosis rather than isolated peripheral upper-extremity DVT. A negative peripheral or bedside ultrasound should not close the workup when symptoms and risk factors remain concerning for central disease.