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Perirenal abscess is a pocket of pus caused by an infection around one or both kidneys.

Perinephric abscess

Most perirenal abscesses are caused by urinary tract infections that start in the bladder, spread to the kidney, and then spread to the area around the kidney. Other causes of perirenal abscess include surgery in the urinary tract or reproductive system and bloodstream infection.

The biggest risk factor for perirenal abscess is kidney stones that block the flow of urine and provide a place for an infection to grow. Bacteria tend to stick to the stones and antibiotics can't kill the bacteria there.

Stones are found in 20-60% of patients with perirenal abscess. Other risk factors for perirenal abscess include:

• Diabetes
• Having an abnormal urinary tract
• Trauma

Symptoms of perirenal abscess include:

• Chills
• Fever
• Pain in the flank (side of the abdomen) or abdomen, which may extend to the groin or down the leg
• Sweats

Signs of perirenal abscess include tenderness in the back or abdomen.

Tests include:

• CT scan
• Ultrasound of the abdomen
• Urinalysis
• Urine culture

In general, quick diagnosis and treatment of perirenal abscess should lead to a good outcome. Kidney stones must be treated to avoid further infections.

In rare cases, the infection can spread beyond the kidney area and into the bloodstream, which can be deadly.

If you have kidney stones, the infection may not go away.

Call your health care provider if you have a history of kidney stones and develop:

• Abdominal pain
• Burning with urination
• Chills
• Fever
• Urinary tract infection

If you have kidney stones, ask your doctor about the best way to treat them to avoid a perirenal abscess. If you undergo urologic surgery, keep the surgical area as clean as possible.

Archer GL. Staphylococcal Infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 310.