16 year old girl presenting with one week of swelling over left leg was found to have DVT involving proximal femoral and iliac systems. Despite treatment with warfarin over next 6 months, there was only partial improvement in symptoms and doppler assessed recanalization. Given the poor response to anticoagulation and young age, MTS was suspected, and later confirmed on magnetic resonance venography. Subsequently, angioplasty and intravascular ultrasound confirmed narrowing with weblike formation within the iliac system. Two stents were placed from the left common iliac to left common femoral veins. Unfortunately, symptoms persisted and she was found to have stent thrombosis less than one month later. This was treated with intravenous thrombolysis with tPA and repeat stenting with two overlapping stents to the occluded veins. Overall, patient continued to have DVT with varying clinical course in spite of almost a year of anticoagulation, until she underwent angioplasty complicated by stent restenosis.
Discussion:
The May-Thurner syndrome is unilateral DVT of the left iliofemoral vein due to compression by right iliac artery against the fifth lumbar vertebra, typically seen in women between the ages of 20-40 years. Incidence of this anatomy ranges from 22 to 32%, but MTS accounts for only 2-3% of all lower extremity DVTs. Chronic compression within the iliac venous system results in intimal proliferation to form webs leading to partial occlusion of veins. These ‘lesions’ elevate venous pressures, increasing the risk of recurrent DVT and treatment failure with medical and endovascular therapies. Non stented lesions have a 73% risk of recurrence, with reduction to 12-14% with stenting and targeted thrombolysis. However, at end of four years, upto 40% patients may require additional procedures to restore stent patency.
Conclusions:
Suspect MTS in young patients presenting with unilateral left sided venous thrombosis, particularly when other risk factors and thrombophilias have been excluded, and when DVT recurs or persists in spite of optimal anticoagulation.