Paget-Schroetter syndrome, also known as effort thrombosis, is a rare condition characterized  by the development of a blood clot (deep vein thrombosis, DVT) in the deep veins of the upper  extremity, particularly the subclavian or axillary veins. It typically affects young, healthy  individuals, often athletes or those engaging in repetitive upper limb activities, leading to  compression of these veins. Clinical presentation includes sudden onset of pain, swelling,  and discoloration of the affected arm. Diagnosis is confirmed through imaging studies such  as ultrasound, CT venography, or magnetic resonance imaging (MRI). Management includes  anticoagulation therapy, thrombolysis, and sometimes surgical intervention to relieve venous  compression. Early diagnosis and treatment are crucial to prevent complications such as  pulmonary embolism or post-thrombotic syndrome.