Acute pyelonephritis with severe
perinephric inflammation with
some fat stranding
no ureteric calculus 0r obstructive pathology
What is perinephric space?
Cone shaped retroperitoneal
kidney, adrenal, fat, fibrous
bridging septa & rich net work
of perirenal vessel & lymphatic
How PNS gets involve?
From outside lesion via -lymphatic
- in malignancy or infection
From inside renal lesion
-acute process, injury to the kidney,calyceal
rupture in acute ureteric obstruction
What is perinephric stranding?
It is linear areas of abnormal
increased attenuation in soft
tissue/ fat- resulting from:
- acute renal inflammatory or infective
lesion with NO HYDRONEPHROSIS
- calyceal rupture in acute ureteric
obstruction with HYDRONEPHROSIS
It is an infection of renal parenchyma
usually caused by an ascending infection
from lower urinary tract
Most common offending pathogen E.coli
It is almost always curable with antibiotic
No lasting damage to kidney
Case review after a month…..
Advised: repeat U/S & CECT
Ultrasound after a month….
Minimal residual ill defined
right renal inferior pole
Perinephric space appears
CECT after a month…..
Minimal residual lesion at
right renal lower pole
Perinephric space clear
Role of imaging…..
Imaging required to exclude-
-previous renal pathology
-high risk patient
Acute pyelonephritis: clinico-pathological
Follow up Imaging…..
Not really essential
Imaging changes can take
3-6 months to resolve
1. Acute bacterial pyelonephritis
Dr Yuranga Weerakkody and Dr Frank Gaillard et al
2. Differential Diagnosis of Perinephric Masses on
CT and MRI
Antonio Westphalen, Benjamin Yeh, Aliya Qayyum,
Anil Hari and Fergus V. Coakle
American Journal Of Roentgenology,2004;183:1697-1702