Emphysematous pyelonephritis

Abstract

Emphysematous pyelonephritis (EPN) is a severe necrotizing infection of the renal parenchyma. The clinical course of EPN can be severe and life-threatening if not recognized and treated promptly. Most of the information has been from case reports, a few large series have also been reported. Using an evidence-based approach, this review describes the pathogenesis, classification, complications, and management of EPN. Emphysematous pyelonephritis (EPN) is an acute severe necrotizing infection of the renal parenchyma and its surrounding tissues that results in the presence of gas in the renal parenchyma, collecting system, or perinephric tissue. The cause for mortality in EPN is primarily due to septic complications. Up to 95% of the cases with EPN have underlying uncontrolled diabetes mellitus. The risk of developing EPN secondary to a urinary tract obstruction is about 25-40%. There are three classifications of EPN based on radiological findings. Acute renal failure, microscopic or macroscopic haematuria, severe proteinuria are other positive findings in EPN. Escherichia coli is the most common causative pathogen with the organism isolated on urine or pus cultures in nearly 70% of the reported cases. A plain radiograph shows an abnormal gas shadow in the renal bed raising the suspicion whereas an ultrasound scan or computed tomography (CT) will confirm the presence of intra-renal gas thus supporting the diagnosis of EPN. Gas may extend beyond the site of inflammation to the sub capsular, perinephric and pararenal spaces. In some cases, gas was found to be extending into the scrotal sac and spermatic cord. Subsequent case studies have shown patients being successfully treated with PCD when used in addition to medical management, with significant reduction in the morality rates. PCD should be performed on patients who have localized areas of gas and functioning renal tissue is present. The treatment strategies include MM alone, PCD plus MM, MM plus emergency nephrectomy, and PCD plus MM plus emergency nephrectomy. In small proportion of patients managed with MM and PCD, subsequent nephrectomy will be required and in these patients the reported mortality is 6.6% Nephrectomy in patients with EPN can be simple, radical or laparoscopic.