In most cases, CT scan is not used to detect gallstones, but this imaging test does have its uses in the biliary system. First of all, the entire main duct can be seen using CT scan because unlike ultrasound, air in the GI tract does not interfere with CT. High-speed CT with computer-assisted reformatting capabilities allows the radiologist to move quickly through numerous images. The ability of CT to find stones in the common bile duct approximates ultrasound. In general, CT scan is a better test for more complicated problems, although it may be used together with ultrasound.
Reasons for treatment of bladder stones include recurring symptoms and risk of urinary tract obstruction. Some stones can be dissolved using dietary modifications and/or medications. Small stones in female dogs may possibly be removed by urohydropropulsion , a nonsurgical procedure. Urohydropropulsion is performed under sedation by filling the bladder with saline through a catheter, holding the dog vertically, and squeezing the bladder to expel the stones through the urethra. Bladder stones can be removed surgically by a cystotomy , opening of the bladder. Stones lodged in the urethra can often be flushed into the bladder and removed, but sometimes a urethrotomy is necessary. In male dogs with recurrent urinary tract obstruction a scrotal urethrostomy creates a permanent opening in the urethra proximal to the area where most stones lodge, behind the os penis . In male cats, stones lodge where the urethra narrows in the penis. Recurrent cases can be treated surgically with a perineal urethrostomy , which removes the penis and creates a new opening for the urethra.