Perinephric bridging septa

Last revised by Daniel J Bell on 31 Mar 2024

Perinephric bridging septa or septa of Kunin (singular: septum) are composed of numerous fibrous lamellae which traverse the perinephric fat 1,2 where they suspend the kidneys within the perirenal space. The septa may act as a barrier or conduit for the spread of pus, blood, urine, and neoplasms in the perinephric space.

In traumatic bleeding, the pressures generated in these closed spaces are considerable and may be adequate to tamponade a bleeding point, which may lead to conservative management.

Three types of bridging septa have been described:

  • renorenal: septa running parallel to the renal capsule and attaching back onto the kidney

  • renofascial: septa connecting the capsule to the adjacent anterior or posterior renal fascia

  • interconnecting fascia: connecting the anterior and posterior layers of the perinephric fascia

The septa can be appreciated as fine lines within the perinephric space extending from the surface of the kidney on CT and MRI.

The septa were first described by Milton Kunin, an American uroradiologist 1.

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