Perinephric abscess

   The common causes of perinephric abscess are shown in picture:-

Other causes are infection of a perirenalhaematoma and perinephric discharge of an untreated pyonephrosisorrenalcarbuncle. A mycobacterialperinephric abscess may arise by extension from a nearby tuberculosisvertebra.

Clinical features

In perinephric abscess there is a high swinging pyrexia, abdominal tenderness and fullness in the loin.

Picture:-

Local signs present early if the infection starts in the lower part of theperinephric fat. Infection at the upper pole is masked by the lower ribs and signs in the loin are less. The white cell count is always marked ly raised but there are characteristically no pus cells or organism in the urine.

Investigation

   The psoas shadow is obscured on the plain x-ray. There may be a reactionary scoliosis- with the concavity towards the abscess and elevation and immobility of the diaphragm on the affected side. A calculus may be present.  Ultrasonography and CT are diagnostic.

Treatment

   Open drainage may be necessary if the abscess cannot be aspirated through a large percutaneous needle. A lumber incision is made under antibiotic cover. This should be large enough to allow the surgeon to open pockets of pus and to explore for an unruptured cortical abscess, which may also be present. A specimen of pus is sent for culture and the wound is closed over a tube drain.