Silent threat after surgery: subclavian and axillary vein thrombosis following clavicle fixation leading to thoracic outlet syndrome.

Thoracic outlet syndrome (TOS) is a rare but significant complication that may occur following clavicular fractures, especially after surgical fixation. We present the case of a 32-year-old woman who developed partial thrombosis of the subclavian and axillary veins as a delayed complication after open reduction and internal fixation (ORIF) of a clavicle fracture with an anatomical plate. Approximately 1 month after surgery, the patient began experiencing pain in the axillary region and mid-arm, symptoms that raised suspicion for TOS. Doppler ultrasonography confirmed partial thrombosis of the distal subclavian vein and acute thrombosis extending from the axillary vein to the subclavian junction. Anticoagulation therapy with apixaban (2.5 mg every 12 hours) was initiated, resulting in significant symptomatic improvement within 1 month, although mild axillary discomfort persisted. Long-term follow-up over 11 months revealed complete resolution of symptoms, and repeat Doppler imaging showed full restoration of venous flow with no residual thrombosis. This case emphasizes the need for clinical vigilance regarding vascular complications after clavicular surgery and demonstrates the therapeutic potential of apixaban in managing venous TOS. Early recognition and timely anticoagulation may lead to favorable outcomes in similar postoperative cases.