Acute torsion of a retroperitoneal renal transplant mimicking renal vein thrombosis.

When imaging a renal transplant, the combination of absent flow in the main renal vein and reversed diastolic flow in the intrarenal arteries is considered highly suggestive of renal vein thrombosis. We present a case of torsion of a transplant kidney presenting with identical findings. Renal transplant torsion in general is a rare entity, previously described only in intraperitoneally placed organs; this case is the first that we are aware of with torsion occurring in a retroperitoneally placed graft.