Renal forniceal or calyceal rupture is the radiographic finding of a perirenal urine leak as a result of ureteric obstruction.
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Gross anatomy
The renal fornices are the thin pointed projections, arising from the lateral aspects of each minor calyx, and extending a short distance into the renal columns. Each fornix contacts the renal pyramid on its inner surface.
Pathology
The renal fornix is the most susceptible part of the renal collecting system to rupture from increased pressure 2,3.
Etiology
Causes include 1,2:
ureteric calculus (~75%)
-
extrinsic compression
malignant
benign, e.g. pregnancy
intrinsic obstruction, e.g. hematoma, tumor
iatrogenic
trauma
Radiographic features
CT
On non-contrast CT, perinephric low-density fluid and fat stranding will be present. On delayed phase imaging contrast will accumulate outside of the collecting system forming a urinoma 2.