What is the diagnosis?
Right renal infarction due to renal artery occlusion.
What is the likely underlying vascular injury and why is there a small amount of renal tissue still enhancing at the inferior pole?
Dissection of the renal artery is most likely. The inferior pole is supplies by a small accessory artery.
The right kidney is non enhancing, apart from a small region of enhancing renal parenchyma in the inferior pole, is swollen and surrounded by stranding. The right renal artery is transected, with no contrast extravasation from its stump to suggest active bleeding. There is a very small right accessory renal artery, arising from the abdominal aorta superior to the origin of the right renal artery, which opacifies with contrast and appears to supply the viable renal tissue.
No convincing pseudoaneurysm detected. Tiny punctate density (on the portal venous phase) adjacent to the inferior aspect of the hilum is of uncertain significance. This may represent a tiny intraparenchymal pseudoaneurysm or a small vein. Variant venous anatomy is demonstrated, with a vein draining the right posterolateral abdominal wall communicating with the right renal vein.
Small retroperitoneal haematoma, at the inferior margin of the right kidney, is present. There is a small amount of blood adjacent to the posterior margin of the spleen, marginally increased in volume compared to the previous study. Stable amount of free fluid in the pelvis. No free intra-abdominal gas is detected. Small locules of subcutaneous gas are present in the left anterior abdominal wall.
The left renal collecting system and bladder contain contrast on the non-contrast phase, consistent with recent contrast administration. The left kidney is unremarkable. The bladder is predominantly collapsed around an indwelling catheter with its balloon inflated. Gas within the bladder is consistent with recent instrumentation.
Subcapsular hypodensity in the liver adjacent to ligamentum teres without local mass effect on adjacent parenchyma is consistent with focal fatty sparing. The pancreas, spleen and adrenal glands are unremarkable. No dilated loops of bowel or evidence of mechanical bowel obstruction. There is mild faecal loading and minor faecalisation of small bowel.