Nondilated obstructive uropathy due to a ureteral calculus

Abstract

U ltrasunography has become the standard approach for investigating suspected urinary tract obstruction because of its safety and high sensitivity.lJ However, it is important to understand that ultrasonography does not detect obstruction directly, but rather its usual consequence: dilatation of the renal collecting system. Unforhmately, urinary tract obstruction is not always accompanied by detectable dilatation36 In these unusual cases of nondilated obstructive uropathy, the results of conventional ultrasonography will be falsely negative, thereby misleading the physician and possibly delaying diagnosis and therapy. Most previously reported cases have been the result of retroperitoneal or pelvic malignancy or fibrosis, or have followed pelvic surgery.56 Here we report a case of nondilated obstructive uropathy caused by a ureter-al calculus in order to alert physicians to the possibility that on occasion, even obstruction due to a urinary stone may be missed by ultrasonography. While this presentation has been noted previously by radiologists,5~7-~ it has not been emphasized in the general medical literature.