- An abscess of the perinephric fat that abuts the renal cortex
- Can arise as a complication either a pre-existing pyelonephritis (majority) or from hematogenous seeding
Perinephric vs renal abscess
|Necrotic Area||perinephric fat between the renal cortex and Gerota's fascia||renal parenchyma|
|Cause||Pyelonephritis (majority)||Pyelonephritis (vast majority)|
|Risk of morbidity||Higher||Lower|
- Sign/symptoms similar to pyelo (fever, CVAT, dysuria)
- Occurs in setting of ascending infection with obstructed pyelo
- Genitourinary infection
- Urethral issue
- Behavioral symptom without detectable pathology
- CBC - Although it is a non-specific finding, a leukocytosis is typically seen.
- Chemistry Panel - Lactic acidosis is a common finding and is seen earlier in the disease course in diabetic patients. Renal insufficiency is also commonly seen as well.
- Urinalysis - Will often show evidence of pyelonephritis, however if the perinephric abscess is secondary to hematogenous spread, the urine could be sterile. Therefore a negative U/A does NOT rule out a perinephric abscess.
- Blood and urine cultures
- Imaging modality of choice
- Sensitivity ~90%.
- Renal ultrasound - A fluid filled mass extending from the renal cortex into the perinephric fat can be seen.
- Antibiotic therapy depends on the suspected cause
- Abscess drainage
- Liu XQ, et al. Renal and perinephric abscesses in West China Hospital: 10-year retrospective-descriptive study. World Journal of Nephrology. 2016 Jan;5(1):108-14.