Are rare, they can be of hematogenis (S. aureus) or can come from an infection developed lower in urinary tract. Infection will ascend from the bladder to the kidneys, causing pyelonephritis initially. Subsequently the bacteria invade the renal parenchyma. Abscesses can develop in the parenchyma perinephric open space.

Kidney stones are the most important risk factors in the development of perinephric abscess. Other risk factors: renal abnormalities, surgery, trauma, kidney, diabetes mellitus. The most common microorganisms involved in pathogenesis are E. coli, Proteus, Klebsiella, and Candida species sometimes.

Clinically, pain is lumbar, flank and abdominal pain. Most patients have fever. The pain may radiate to the groin and leg.

Diagnosis of this type of abscess is sometimes late, so mortality is considerable. We use for diagnostic imaging and computer tomography abdominal kidney ecagrafia.

Treatment consists of drainage of purulent collection and application of targeted therapies with antibiotics.