Renal Pathology
Pediatric renal disease, including pyelonephritis, ureteropelvic junction (UPJ) obstruction and rarely nephrolithiasis, is a frequent cause of abdominal pain. Although the sensitivity of US in detecting acute pyelonephritis is low, the sensitivity for complications, including abscess and pyonephrosis, is quite high.[29] On US, the infected kidney appears enlarged with focal or diffuse areas of abnormal echogenicity and loss of corticomedullary differentiation. Power Doppler increases sensitivity by detecting decreased perfusion in the affected area of the kidney.[30,31]
UPJ obstruction can be secondary to intrinsic causes or extrinsic compression secondary to bands, kinks or aberrant vessels. Patients may present with a palpable mass, urinary tract infection or hematuria. US can detect a dilated renal pelvis communicating with dilated calyces, however, the renal pelvis is dilated out of proportion to the calyces and the distal ureter is not seen. It is essential to differentiate UPJ obstruction from a multicystic dysplastic kidney, which very often occurs in the contralateral kidney and appears as multiple non-communicating cysts of varying sizes.[31–33]
Appl Radiol. 2014;43(8) © 2014 Anderson Publishing, Ltd.
