Sonographic features of necrosed renal papillae causing hydronephrosis.

OBJECTIVE To describe the sonographic appearance of ureteric obstruction due to necrosed papillae. METHODS In this study, carried out over 3 years 6 months, patients with diabetes mellitus who had renal colic were studied by sonography. RESULTS In 15 patients with hydronephrosis, there was a soft tissue mass of necrosed papillae filling the ureteric lumen at the site of obstruction. Necrosed papillae were seen in medullary cavities of the ipsilateral kidney in 5 patients. Ureteroscopic removal of necrosed papillae was done in 13 patients. One patient was not fit for an invasive procedure. CONCLUSIONS When patients predisposed to renal papillary necrosis have renal colic, and sonography fails to show a ureteric calculus, it is best to look for necrosed papillae in the ureter, which may be causing obstruction.