Emphysematous pyelonephritis

2. Emphysematous pyelonephritis

It is a rare necrotizing infection of kidneys with abnormal accumulation of air within parenchyma, pelvicalyceal system and in perinephric soft tissue. If not treated early, it can lead to morbid sepsis.

Epidemiology

Adult females are commonly affected. It tends to affect patients with uncontrolled diabetes, urinary tract obstruction, immunocompromised individuals, neoplasms or sloughing of papilla.

Clinical features

Presenting complaints are fever, chills, flank pain, nausea and vomiting.

Lab parameters

Leucocytosis, raised white blood cell count, ESR, C-reactive protein, hyperglycaemia, acidosis, dehydration and electrolyte imbalance are prominent findings.

Pathology

Glucose fermenting bacteria such as E. coli (most common), Klebsiella, Pseudomonas and Proteus mirabilis are the causative organisms. Proteus, Aerobacter and Candida are additional causative organisms.

Imaging

Plain radiograph and IVP

Air is visualized as mottled lucencies within the renal fossa or crescentic collections of gas within the Gerota’s fascia.

USG

On grey scale imaging, there may be nonvisualization of the kidney due to air. Dirty echogenic foci with reverberation/ring-down artefacts representing gas (‘dirty shadowing’) in renal parenchyma, pelvicalyceal system and perinephric soft tissue are also seen. Renal enlargement may be seen.

CECT

CTU is the most accurate and diagnostic modality. Kidneys appear enlarged and show destruction of renal parenchyma with accumulation of air in the parenchyma pelvicalyceal system and perinephric soft tissue (Fig. 10.12.2.2.1).