Perinephric abscess. Modern diagnosis and treatment in 47 cases.

The records of 47 patients with a perinephric abscess diagnosed from 1975 to 1986 at 8 San Francisco Bay Area hospitals were reviewed. The mean age was 51 years. Fifty-five percent were females and 45%, males. The left kidney was affected in 47% of cases, the right kidney in 40%, both in 4%, and a transplanted pelvic kidney in 9%. Fever (55%), chills or diaphoresis (47%), flank pain (40%), abdominal pain (40%), and nausea or vomiting (32%) were the most common presenting symptoms. About half the patients had symptoms for 1 week or less and 12% had no symptoms. Fever was documented before diagnosis in 88% of patients. Abdominal mass (13%) or tenderness (49%), and flank mass (9%) or tenderness (42%) were seen less frequently, and 11% of patients did not have fever, flank, or abdominal findings. The most frequent underlying conditions included previous urologic surgery (45%), previous urinary tract infection (38%), diabetes mellitus (36%), and urinary tract stones (36%). Cultures of perinephric abscesses yielded gram-negative aerobes in 52% of patients, primarily Escherichia coli. Staphylococcus aureus was isolated in 26% of patients and anaerobes in 17%. A single pathogen was isolated in 71% and multiple isolates in 29%. Of interest and great potential therapeutic importance was culture of anaerobes, primarily Bacteroides spp. in 17%, Enterococcus spp. in 7%, and Candida albicans in 7%. Positive blood and urine cultures identified perinephric abscess organisms exactly in 58% and 37% of cases, respectively. Routine laboratory tests such as the white blood cell count and urinalysis were insensitive and non-specific for perinephric abscess. Leukocytosis and anemia at admission were seen in slightly more than half of the patients. For radiologic diagnosis, computerized tomographic scanning was most helpful. Ultrasound and intravenous pyelography were falsely negative in about one-third of cases. Mortality (13%) was low in this series when compared with earlier studies, and probably reflects modern medical care. Six patients (13%) died during hospitalization, 2 of whom had diagnosis of PNA established only at autopsy. Drainage of the perinephric abscess was carried out by open surgical drainage in 64% of patients, percutaneous drainage in 19%, and both in 13%. The initial procedure, whether open surgical drainage or percutaneous catheter drainage, was usually successful. Late complications included nephrocutaneous fistulas in 3 patients and disseminated candidiasis in 1 patient.