Emphysematous pyelonephritis

Case contributed by Safwat Mohammad Almoghazy
Diagnosis certain

Presentation

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.

Patient Data

Age: 20 years
Gender: Female

Day 0 (on admission)

ultrasound

Longitudinal scan of the left kidney showing multiple large echogenic foci of air at its lower pole extending to the renal parenchyma. 

The rest of the abdominal organs are unremarkable. 

Case courtesy of Dr AMIR SHALAN

Annotated image

ultrasound

Longitudinal scan of the left kidney showing multiple large echogenic foci of air ( red arrow) at its lower pole extending to the renal parenchyma. Note the dirty shadow ( red *).

Day 0 (on admission)

x-ray

Conventional radiography demonstrates small abnormal collections of gas within the renal fossa or within the bowel.

CT KUB at the day 0 after US

ct

The left kidney is seen enlarged ins size shows multiple calyceal air density extending to its renal parenchyma with mild backpressure changes associated with perinephric fat stranding, yet no hyperdense stones noted along with the left urinary system.

A mild left hydroureter is noted with no underlying stones.

The right kidney is normal in site, size and orientation. No renal calculi, contour deforming abnormality or perinephric collection is detected.

The ureters and the urinary bladder are unremarkable.

The rest of visualized organs including the GB, CBD, pancreas, spleen, adrenals, and bowel loops show no gross abnormality, although this is a suboptimal study due to lack of contrast media.

No free air or significant lymphadenopathy detected.

Both lung bases are clear.

The visualized parts of the bones show no evidence of destructive lesion.

conclusion:

Type 2 left emphysematous pyelonephritis.

2 days before a day of the...

x-ray

2 days before a day of the 1st presentation to causality

Conventional radiography 2 days before demonstrate fixed or unchanged (as regarding the shape, size and location) a small abnormal collection of gas within the renal fossa and not in the bowel.

Annotated images 2 days apart

x-ray

Conventional radiography two days apart showing unchanged (as regarding the shape, size and location) a small abnormal collection of gas within the renal fossa. Note the red arrows.

Enhanced CT A/P to rule out...

ct

Enhanced CT A/P to rule out abscess formation after 5 days of admission

Previous CT KUB study since few days was compared. 
Double J stent is noted in the left urinary system. 
The left kidney is swollen hypo-perfused left kidney showing pyelonephritic changes with focal cortical and subcapsular fluid collection measures 2.2x2.8 cm suggesting small abscess formation with mild perinephric fat stranding. 
No right-sided focal or diffuse parenchymal lesion is detected. 
No calculi, hydronephrosis.
Both ureters are normal in course and calibers with no calculi, filling defect, hydroureter or periureteric fat stranding seen.
The urinary bladder is normal in outline and enhancement. 
Thin rim of pelvic and both iliac fossa fluid. 
Lung bases show mild right pleural effusion with basal collapse. 

Impression

Swollen hypo-perfused left kidney showing pyelonephritic changes with focal cortical and subcapsular collection suggesting small abscesses collections formation.

Case Discussion

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.

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