Analysis of 777 cases with obstruction of the ureter or extrahepatic bile duct by ultrasonography after normal saline retention enema

BACKGROUND Conventional transabdominal ultrasound usually fails to visualize parts of the ureter or extrahepatic bile duct covered by bowel gas. In this study, we propose a new method for gaining acoustic access to the ureters and extrahepatic bile duct to help determine the nature of obstruction to these structures when conventional transabdominal ultrasound fails. METHODS The normal saline retention enema method, that is, using normal saline-filled colons to gain acoustic access to the bilateral ureters and extrahepatic bile duct and detecting the lesions with transabdominal ultrasonic diagnostic apparatus, was applied to 777 patients with obstructive lesions, including 603 with hydroureter and 174 with dilated common bile duct, which were not visualized by conventional ultrasonography. The follow-up data of all the patients were collected to verify the results obtained by this method. RESULTS Of the 755 patients who successfully finished the examination after normal saline retention enema (the success rate of the enema is about 98%), the nature of obstruction in 718 patients was determined (the visualizing rate is approximately 95%), including 533 with ureteral calculus, 23 with ureteral stricture, 129 with extrahepatic bile duct calculus, and 33 with common bile duct tumor. CONCLUSIONS Colons filled fully with normal saline can surely give acoustic access to the bilateral ureters and extrahepatic bile duct so as to determine the nature of obstruction of these structures when conventional transabdominal ultrasound fails.