a purulent inflammation of the connective tissue adjacent to the kidney. It is caused by the spread of microorganisms through the connective tissue from a diseased kidney or large intestine or from a distant inflammatory focus by way of the circulatory system. The symptoms are an elevation in body temperature to 38°C or higher, chills, and pain in the lumbar region and corresponding side of the abdomen. Palpation of the loin (lumbus) is very painful. The lumbar muscles become rigid, and then the accumulation of infiltrate makes the lumbar region protrude. The disease may be complicated by an abscess opening into the abdominal cavity, pleural cavity, or intestine. It is sometimes necessary to sample the infiltrate by centesis for diagnostic purposes. Treatment involves lancing the abscess and administering antibiotics.