Role of CT to Evaluate Renal Imaging Features of Acute Pyelonephritis and it's Complications

Abstract Background: Acute pyelonephritis is infection of the renal parenchyma and its collecting system. It can present as complicated pyelonephritis especially when associated with risk factors such as diabetes, sickle cell anemia, immunocompromised patients, etc. Complications manifest as renal abscess, pyonephrosis, lobar nephronia, emphysematous pyelonephritis and renal papillary necrosis.1 CT is the most sensitive modality for early diagnosis of acute pyelonephritis, to distinguish between complicated and uncomplicated pyelonephritis and assess the complications. Materials & Methods: A retrospective analysis of 100 patients who presented with clinical symptoms and urinalysis of acute pyelonephritis had undergone contrasted enhanced computed tomography of the Abdomen for assessing renal imaging features of acute pyelonephritis, its manifestations and complications. Results & Discussion: Out of 100 cases of acute pyelonephritis, the imaging findings were diffuse renal enlargement (96%), perinephric & perirenal fascial thickening (95%), streaky nephrogram (53%), urothelial thickening of renal pelvis (17%), Gas in renal parenchyma or collecting sugges­tive of emphysematous pyelonephritis (13 %), renal abscess (11 %), filling defects in the calyceal system on excretory phased imaging suggestive of papillary necrosis (4 %), hyperdense dependent contents within the pelvic calyceal system suggestive of pyonephrosis (2 %) and well defined hypoenhancing focal area within renal parenchyma without cortical rim sign suggestive of lobar nephronia (1 %). Out of 100 cases 69 cases were diagnosed as uncomplicated acute pyelonephritis and 31 cases were diagnosed as complicated pyelonephritis. Conclusions: CT is the modality of choice for early diagnosis of acute pyelonephritis, assessment of its complications and serial follow ups for progression of complications.