Presentation
Left flank pain and acute urinary retention associated with vomiting and fever with chills for 3 days. History of diabetes mellitus and hypertension.
Patient Data
Kidneys are normal in size and parenchymal echogenicity. Mild left hydronephrosis. No hydronephrosis is seen on the right side. A calculus measuring 1 cm is noted at the lower pole of the left kidney.
A radiopaque calculus measuring 6 x 10 mm (average density=950 HU) is seen in the lower pole calyx of the left kidney. Mild left hydronephrosis and mild left perinephric fat stranding. Prominent/mildly dilated left ureter traceable throughout its course without any radiopaque calculus. Air/gas is seen in the left renal collecting system, left ureter and urinary bladder. A Foley catheter is seen in the urinary bladder.
Relatively enlarged left kidney showing poor parenchymal enhancement on the arterial and venous phase imaging. An ill-defined non-enhancing area containing gas foci, measuring approximately 4 x 4 cm is seen at the upper pole of the left kidney. Multiple small focal hypodensities (without any gas foci) are seen in the remaining left renal parenchyma. Mild left perinephric fat stranding. No focal collection or gas is seen in the left perinephric space. No definite gas is seen within the left renal collecting system itself. Left-sided double-J stent is seen in place. A small calculus is seen in the left renal pelvis. No ureteric stone or hydroureteronephrosis is seen. Poor contrast excretion is noted by the left kidney on delayed excretory phase imaging. The right kidney is normal. Foley catheter and small amount of air/gas are seen in the smooth walled urinary bladder. Patent and well-opacified renal arteries and veins.
Mildly enlarged liver. Mild ascites, small bilateral pleural effusions with basal partial collapse/consolidation and diffuse edema in the subcutaneous soft tissues, suggestive of anasarca.
Positive laboratory investigations (urine analysis, blood culture), operation notes of the left nephrectomy and histopathology report of the nephrectomy specimen.
Case Discussion
Initial plain CT scan showed air in the renal collecting system, ureter and urinary bladder, consistent with emphysematous pyelitis (relatively benign entity).
Follow-up contrast-enhanced CT scan showed mildly enlarged poorly enhancing left kidney, containing multiple focal hypodensities (suggestive of pyelonephritis) and an ill-defined hypodensity containing multiple gas foci at the upper pole, suggestive of emphysematous pyelonephritis; evolving renal abscess can be one possible differential diagnosis of the upper pole lesion.
Despite multiple antibiotics, the patient's condition did not improve and ended up in a nephrectomy. The patient recovered completely after the nephrectomy.