Abscess drainage. Pus and blood being drained out of an abdominal incision into a bowl. The pus is from a perinephric abscess. This is an abscess in the region surrounding a kidney (the perinephric space). It is difficult to diagnose and is a rare complication of urinary tract infections and also develops from other kidney abscesses. Because the onset is slow, large amounts of pus may form from the bacterial infection. Treatment is by drainage, as here, through an incision in the skin. Where to make the incision depends upon the exact nature of the perinephric abscess. Drainage may take several days. Antibiotics are used to treat the infection and to prevent further infection.