CT as a Diagnostic Tool for Emphysematous Pyelitis: A Case Report.

Gas forming infections of the renal collecting system occurs because of organisms like Escherichia coli, Klebsiella, and Proteus. If the gas is restricted to the collecting system, without causing involvement of the cortex, it is called emphysematous pyelitis; whereas, invasion and penetration of the cortex imply a more gruesome diagnosis of emphysematous pyelonephritis. A 59-year-old male patient, previously diagnosed with a large right renal calculus and having multiple co-morbidities presented to the surgery department with right flank pain; Double J (DJ) stenting was done to relieve the pain from colic due to obstructive renal calculi; the patient subsequently discharged without any post-procedural complications. The patient came back a month later with similar complaints and multiple spikes of fever. Blood and urine culture revealed growth of Escherichia coli. The first line radiological investigations, like X-ray and ultrasonography, were suggestive of the presence of air in the pelvis, ureter, bladder; confirmation by CT revealed the presence of air in the collecting system, including the calyx. This air was seen invading focally into the anterior renal cortex. Also, the DJ stent had migrated into the proximal ureter.  The patient had developed emphysematous pyelitis predominantly, which had developed an overlapping component of pyelonephritis. The aetiology for air in the renal system was infection by Escherichia coli. CT proved to be diagnostic in differentiating both of them, as the presence of air entering the renal cortex was detected only on CT. Subsequently, prominent initiation of antibiotic therapy and replacement of DJ stent was carried out, following which the patient recovered fully within two weeks.