An Unexpected Complication of Training: A Rare Case of Paget-Schroetter Syndrome in an Adolescent Athlete.

Paget-Schrotter syndrome (PSS), or exercise-induced upper-extremity deep vein thrombosis (UEDVT), is an uncommon but clinically significant phenomenon that typically affects young, otherwise healthy individuals engaged in repetitive strenuous physical activity involving the upper extremity. This case highlights a rare case of PSS in a 16-year-old female cheerleader presenting with a sudden onset of right upper-extremity swelling and cyanosis following strenuous exercise and the recent initiation of combined oral contraceptive pills. Initial evaluation with duplex ultrasonography was unremarkable, and the patient was consequently discharged with supportive care. Persistent swelling, aching, and decreased range of motion led to a repeat emergency department visit nine days later, where subsequent evaluation with duplex ultrasonography and computed tomography angiogram revealed an occlusive thrombus of the right subclavian and axillary veins. Following hospital admission with the pediatric hematology service, therapeutic anticoagulation was initiated, resulting in the gradual resolution of symptoms. This case highlights diagnostic challenges in early PSS, the interplay between strenuous exercise and estrogen-related hypercoagulability, and the importance of early detection in preventing symptom progression. By gaining a more thorough understanding of this disease process and presentation, clinicians can enhance their ability to identify and treat PSS early and effectively, thereby reducing complications and improving patient outcomes in the future.