Hemodialysis fistula stenosis caused by extrinsic vascular compression: The May-Thurner of fistulas.

Significant venous outflow stenosis of a forearm arteriovenous fistulae caused by an extrinsic vascular compression is a very rare entity (no reported cases in the literature). We report a case of high venous pressures during dialysis, secondary to an extrinsic compression of the underlying brachial artery that was diagnosed with Doppler ultrasound. The stenosis localization resembles the typical and frequent juxta-anastomotic venous outflow stenosis. This similarity can be a confounding factor and can lead to failure of conventional treatments. Careful surgical technique of arteriovenous graft creation and Doppler ultrasound mapping can prevent this entity.