Double May-Thurner syndrome causing chronic deep vein thrombosis and natural venous femoro-femoral bypass: a description of rare case.

May-Thurner syndrome (MTS) belongs to a group of uncommon vascular syndromes. It consists in left common iliac vein (LCIV) compression between the right common iliac artery (RCIA) anteriorly and the lumbar spine posteriorly. A compression of LCIV by the left common iliac artery (LCIA) or by both iliac arteries were described. We present a rare case of "double MTS" which consist in double stenosis of LCIV by both RCIA and LCIA. Double MTS can cause acute or chronic DVT; this latter could be clinical manifest or well compensated. A 58-year-old woman with chronic mild pelvic pain underwent Doppler Ultrasound (US) of the pelvis and lower extremity vessels which showed thrombosis of both LCIV and ipsilateral common femoral vein caused by the extrinsic compression by both common iliac arteries against the spine. CT angiography confirmed the US data and ruled out other causes of compression. CT scan also showed the development of a natural venous femoro-femoral bypass which allowed to counteract the venous stasis and compensate venous drainage. Therefore, we decide for a long-term prophylaxis with anticoagulant drugs and doppler US follow-up at 6 months. In conclusion, doppler US is a non-invasive, low-cost, repeatable and sensitive method which allows to diagnose MTS and associated DVT. It may be considered the first level exam which allows to easily detect pelvic vascular compression syndrome.