Endoluminal sonographic imaging of the ureteropelvic junction.

Endoluminal ultrasound imaging of the ureter can demonstrate the periureteral anatomy. Ultrasound probes are available as catheters from 3.5F to 6.2F. The transducer is available as a 12.5 or 20 MHz design and gives a cross-sectional image with penetration of 1.5 to 2 cm. Endoureteral ultrasonography has demonstrated blood vessels associated with the obstructed ureteropelvic junction (UPJ) in more than 50% of patients. These vessels have been located at all sites adjacent to the UPJ. The anteromedial location is the most common site. In comparison, only 8 significant crossing vessels were found in 44 patients with a normal UPJ. Inspection of the UPJ with a high insertion of the ureter demonstrates a characteristic sonographic image with a septum between the ureteral and renal pelvic lumen. Endoluminal ultrasonography of the obstructed UPJ can be used to guide the site of endopyelotomy to avoid damage to adjacent vessels. The presence of such vessels may also be related to the success of the procedure. An ultrasound-guided cutting device has been developed for preclinical studies.