A 20-year-old woman presented to our hospital complaining of fever and repeated vomiting for several days. She had no relevant medical history and had been in good health.

An abdominal ultrasound examination found a left kidney with large echogenic foci with ‘dirty’ shadowing within. This appearance was highly suggestive of air inside the kidney.No renal mass or stone was seen and there was no perinephric fluid collection.

Conventional abdominal radiographic series have done in causality (on the same day and two days before) were reviewed and demonstrating fixed abnormal small collections of gas within the left renal fossa. Emphysematous pyelonephritis was highly suspected on the basis of these radiographic and US studies.

CT KUB examination was then performed, confirming that there were multiple gases locules inside the left renal pelvicalyceal system and renal parenchyma and confirming the diagnosis of emphysematous pyelonephritis.

Double J stent was inserted and antibiotics started, then patient responded poorly and after more than 5 days complaining of persistent fever and enhanced abdominopelvic CT examination was then performed and showed swollen hypo-perfused left kidney with pyelonephritic changes with focal cortical and subcapsular fluid collection suggesting a few small collections of abscesses formation.

Emphysematous pyelonephritis is a rare but life-threatening necrotizing infection of the kidney caused by gas-forming bacteria. Although it can present a fulminant clinical picture of sepsis, relatively mild symptoms can be encountered. Our patient was in a stable condition with symptoms suggesting a urinary tract infection. Ultrasound was detected renal gas. On ultrasound requires a high index of suspicion and the recognition of echogenic foci with ‘dirty’ shadowing. It should be differentiated from renal stones, which are echogenic but have clean shadows.