Fact-sheet: Acute pyelonephritis
Updated on 12/17/2022 at 5:33 PM
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Definition
Upper urinary tract infection of bacterial origin causing acute inflammation of the renal parenchyma and the pyelocaliceal epithelium.
Clinical features
Acute onset presentation combining febrile flank pain, nausea/vomiting, urinary frequency, and dysuria.
Tenderness on lumbar percussion.
Laboratory findings
Biological inflammatory syndrome.
Urine dipstick: nitrites and leukocytes.
Urine culture: leukocytes and identification of the causative organism.
Need to perform antibiotic susceptibility testing and blood cultures.
Ultrasound
Globular Kidney, sometimes with a heterogeneous appearance of the renal parenchyma.
Search for complicated forms:
- abscess
- dilatation of the pyelocaliceal system indicating an obstruction requiring prompt urinary diversion
A normal ultrasound (50% of cases) does not exclude the diagnosis of Acute pyelonephritis.
CT
- Globular Kidney, slightly hypodense before contrast injection
- Heterogeneous enhancement of the renal parenchyma after injection, with triangular parenchymal enhancement defects with a peripheral base
- Enhancement of the pyelocaliceal walls
- Possibly identifying the cause of the infection (urinary calculus, tumoral obstruction of the urinary tract, prostatic hypertrophy).
- Enhancement of the pathological parenchyma is always lower than that of the healthy parenchyma.
- On delayed acquisition, retention of contrast material may be observed in the pathological areas.
- Subcapsular and perirenal effusion.
Differential diagnosis
Superinfected renal infarctus, but the characteristic cortex corticis enhancement is generally present.