An adolescent female presented to the emergency room with pain, swelling and a palpable lump in the right axilla following activity on a rowing ergometer. The differential diagnosis at the time of presentation was deep vein thrombosis, mass compression and cellulitis. An ultrasound scan revealed an occlusive thrombus of the right axillary and subclavian veins, basilic vein and proximal cephalic vein. The patient underwent pharmacomechanical thrombolysis followed by catheter-directed thrombolysis. Dynamic venogram testing revealed venous thoracic outlet syndrome (VTOS) and a transaxillary first rib resection was performed to decompress the costoclavicular space. Genetic testing revealed the patient was heterozygous for factor V Leiden. Two rounds of balloon dilatation plasty were performed to relieve recurring symptoms due to scarring and persisting compression, 1 and 3 years post rib resection. After extensive shared decision-making, the patient returned to sport, reporting only intermittent symptoms of post-thrombotic syndrome. This case sheds light on the importance of early diagnosis of VTOS for successful return to sport.