Renal abscess is a collection of purulent material within the renal parenchyma.

Renal abscess can be a complication of pyelonephritis (possibly due to the coalescence of microabscesses) and is most commonly caused by gram-negative bacteria. It may also occur by hematogenous seeding of the kidney in the setting of bacteremia (frequently caused by Staphylococcus aureus).

Symptoms are consistent with symptoms of pyelonephritis and typically include fever and unilateral flank pain.

Risk factors for this infection include diabetes mellitus (type 1, type 2) and abnormalities of the urinary tract, including renal stones and polycystic kidney disease.

Related topic: Perinephric Abscess