Experience with endoluminal ultrasonography in the urinary tract.

Ultrasonography has been an invaluable tool in the field of urology for its noninvasiveness, safety, and relatively low cost. However, examination of the ureter with ultrasound is difficult because of the distance of the transducer from the ureter and because of intervening structures such as nonconductive bowel gas. As smaller probes have become available, attempts have been made to apply them to endoluminal use. Endoluminal ultrasonography has been employed in urology to examine the proper placement of injected collagen, diagnose urethral diverticula, diagnose and stage upper tract transitional-cell carcinoma, locate crossing vessels to guide endopyelotomy, diagnose submucosal calculi, and examine the severity and length of ureteral strictures.