The cortical rim sign of renal infarction

A case is described of bilateral renal infarction following graft replacement of an abdominal aortic aneurysm. The patient developed oliguric renal failure following operation. An intravenous urogram on the 27th post-operative day showed a thin dense rim around each kidney during the nephographic phase. This corresponded to a viable rim of cortex at post-mortem. It is likely that this was due to collateral circulation from the renal capsule. It is considered that this “nephrographic rim” sign is diagnostic of total renal infarction or cortical necrosis. Its demonstration depends on high-dose nephrotomography.