Fast Five Quiz: Are You Prepared to Confront Pyelonephritis?

Vecihi Batuman, MD


February 26, 2018

Patients with renal corticomedullary abscesses often present with chills, fever, and flank or abdominal pain, and patients may have dysuria and/or nausea and vomiting. Leukocytosis may be present. Bacteriuria, pyuria, hematuria, or proteinuria may be present, as the intrarenal abscesses drain in the collecting system, but the urinalysis results may be normal in as many as 30% of patients. Bacteremia may be observed in acute focal or multifocal bacterial nephritis. Corticomedullary abscess is usually associated with a urinary tract abnormality, such as vesicoureteral reflux or obstruction. It is commonly caused by Enterobacteriaceae.

Renal cortical abscess (renal carbuncle) is an uncommon condition that is usually caused by the hematogenous spread of S aureus. Microabscesses develop in the cortex and coalesce to form a circumscribed abscess that may or may not communicate with the collecting system. This process takes days to months.

Emphysematous pyelonephritis, which most commonly occurs in patients with diabetes, is a severe, necrotizing form of acute multifocal bacterial nephritis with extension of the infection through the renal capsule. This leads to the presence of gas within the kidney substance and in the perinephric space. Persons with diabetes (with or without obstruction) account for 85%-100% of cases, although some cases have occurred in patients without diabetes who had obstruction. Females outnumber males (2-6:1).

Xanthogranulomatous pyelonephritis is a rare form of pyelonephritis that is almost always associated with chronic obstruction (eg, from staghorn calculus, other calculus, stricture, or tumor). In adults, the female-to-male ratio is 3:1; in children, it is 1.1:1. It is a chronic infection that finally manifests acutely with fever and flank pain or tenderness, and it may be complicated by a flank mass, cutaneous fistula, septic arthritis, or hematochezia if extension has occurred beyond the renal capsule. Kidney function is absent (71%) or poor (25%) in almost all cases. Diagnosis is difficult preoperatively.

For more on the complications associated with acute pyelonephritis, read here.


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