We refer to a very rare case of catheter-related thrombosis in a trauma patient with persistent left and absent right superior vena cava. The role of ultrasound examination in the early diagnosis and treatment of thrombosis in the setting of intensive care unit (ICU) is thoroughly discussed. A 30-year-old man was admitted to the ICU due to multiple trauma. Six days after right internal jugular vein (IJV) catheter insertion, and during a vascular ultrasound examination, an IJV catheter-related thrombosis was diagnosed. Hence, the catheter was removed, and a follow-up ultrasound examination revealed thrombus remnant in the IJV extended into brachiocephalic vein. Subsequently, to exclude a possible extension of the thrombus in the superior vena cava, a transesophageal echocardiography (TEE) examination was performed. The latter revealed a distended coronary sinus and the presence of persistent left superior vena cava (PLSVC). Additionally, TEE examination disclosed thrombus remnant within the PLSVC that was also confirmed with CT venography. Anticoagulant therapy was started thus preventing major complications such as coronary sinus obstruction. This case underlines the role of cardiovascular ultrasound examination as an important tool in performing variety of monitoring in the setting of the ICU.