Perinephric Stranding in Urostomy Patients

Understanding Perinephric Stranding

Perinephric fat stranding (PFS) represents inflammatory changes in the fat surrounding the kidney and is a secondary CT finding that indicates an active pathologic process, according to the American College of Radiology 1, 2

In patients with urostomy, PFS is not normal and indicates ureteroileal stricture with obstruction, which is the most common cause, as reported by the American College of Radiology 3, 4
PFS combined with hydronephrosis suggests infected obstructed kidney requiring emergent decompression, as recommended by the American College of Radiology 1, 4
PFS with perirenal fluid suggests anastomotic breakdown or ureteral injury, according to the World Journal of Emergency Surgery 2

If PFS is identified on CT in a urostomy patient, checking for fever, leukocytosis, and sepsis signs is mandatory, and PFS with systemic infection requires emergent percutaneous nephrostomy, as stated by the American College of Radiology 1, 4
Assessing for hydronephrosis/hydroureter is necessary, as PFS combined with collecting system dilation confirms obstruction, according to the American College of Radiology 1
Performing a loopogram is recommended to evaluate for reflux into ureters and identify stricture location, as suggested by the American College of Radiology 3, 5

For PFS with pyonephrosis (infected obstruction), emergent percutaneous nephrostomy is lifesaving and usually appropriate, with a patient survival rate of 92% with PCN versus 60% with medical therapy alone, as reported by the American College of Radiology 1, 4
For PFS with non-infected obstruction, percutaneous nephrostomy followed by delayed surgical revision is usually appropriate, according to the American College of Radiology 3, 4
Antegrade nephroureteral catheter placement is preferred over double-J stents due to mucus plugging risk, as recommended by the American College of Radiology 3, 5

Do not assume PFS is "normal" in urostomy patients, as it always indicates active pathology requiring investigation, according to the American College of Radiology and the World Journal of Emergency Surgery 1, 2
Do not delay drainage if infection is present, as PFS with fever/sepsis requires emergent decompression within hours, as stated by the American College of Radiology 1, 4
Do not rely on hematuria, as up to 25% of ureteral injuries lack hematuria despite PFS, according to the World Journal of Emergency Surgery 2
Do not use double-J stents as first-line in ileal conduits, as they occlude rapidly from mucus, and retrograde nephroureteral catheters are preferred, as recommended by the American College of Radiology 3, 5