Renal and perinephric suppurations (or abscesses) commonly share similar clinical manifestations, but their pathophysiology, complications, and treatment are not identical.
The clinical manifestations, diagnosis, and management of renal and perinephric abscesses will be reviewed here. Complicated pyelonephritis in general, emphysematous pyelonephritis, malakoplakia, and xanthogranulomatous pyelonephritis are discussed in detail separately. (See "Acute complicated cystitis and pyelonephritis" and "Emphysematous urinary tract infections" and "Xanthogranulomatous pyelonephritis".)
PATHOGENESIS AND MICROBIOLOGY
Renal and perirenal abscesses can complicate a urologic infection (usually due to gram-negative enteric bacilli or a polymicrobial infection) [1-4] or occur secondary to hematogenous seeding (mostly due to Staphylococcus aureus).
Renal abscess occurs more frequently than perinephric abscess. Both start with tissue necrosis (lobar necrosis in renal abscess; perirenal fat necrosis in perinephric abscess). Renal abscess forms a walled-off cavity; perinephric abscess consists of a more diffuse liquefaction located between the renal capsule and Gerota’s fascia. Septation of the perinephric abscess is frequent, which makes drainage more difficult than that of renal abscess.
Renal abscess — Focal renal abscesses typically occur in the setting of generalized pyelonephritis, particularly in patients with anatomical abnormalities that predispose to infection. As an example, approximately two-thirds of renal abscesses caused by gram-negative organisms occur in patients with a renal stone or vesicoureteral reflux . In such cases, the kidney may have suffered previous episodes of infection and be chronically pyelonephritic and scarred.