Urethrotomy and Urethrostomy in the Dog Daniel D. Smeak, DVM, DACVS An incision, or urethrotomy, is made into the urethral lumen to remove or relieve an obstruction temporanly. When permanent diversion of urine flow proximal to an obstructed, severely damaged, or diseased urethra is required, a urethrostomy is performed. Urethrostomy is also performed to diminish the risk of urethral obstruction due to recurrent urinary calcuh that are not hkeiy to be resolved w~th medical therapy. Whenever possible, to reduce the risk of urethral stricture or recurrent urinary tract infection, urethral surgery ts avoided when an obstruction can be relieved by retrohydropropulslon or catheterizatton. Urethrotomy can be performed in the prescrotal or perineal regions depending on the level of the urethral obstruction. Although urethrostomy can be made in the perineal and antepubic positions, scrotal urethrostomy is the procedure of choice provided the lesion ~s distal to this area. Specific urethrotomy and urethrostomy procedures are descrtbed, including discusston about selection of the appropriate procedure for the urethral problem, patient stabilization considerations, general postoperative management, and risk of complications. Copyright © 2000 by W.B. Saunders Company medical emergencies and general anesthesia should not be attempted until fluid and electrolyte imbalances are corrected. 2 When retrograde hydropropulslon is deemed unsuccessful in dogs with lodged urethral calcuh, try to feed a well-lubricated smaller gauge urethral catheter past the lesion. If this is not possible, a urethrotomy over or proximal to the lesion, or tube cystostomy can be performed under local anesthesia and narcotic sedation to allow free urine flow from the bladder. 3-5 Most lodged stones can be removed through a urethrotomy incision, and, once this has been done, the more proximal stones generally can be flushed back into the bladder. These uroliths are removed later by cystotomy when the animal is stable. If necessary, a larger catheter can be passed temporarily through the urethrotomy to dwert urine and to monitor urine output. Appropriate fluids are given intravenously and, when hydration and electrolyte balance has been restored, additional surgery such as urethrostomy or cystotomy can be instituted. Culture a urine sample collected by cystocentesis before appropriate intravenous antibiotics are begun. T he goal of urethrotomy or urethrostomy is to reestablish urethra continuity. 1 Urethrotomy and urethrostomy are performed to relieve a urethral obstruction to allow urine flow around an irreversibly diseased or damaged urethra. These procedures are performed either over the obstructive lesion or proximal to the site of narrowing, obstruction, or destruction of the urethra. A longitudinal incision, or urethrotomy, is made percutaneously into the urethra to gain access for removal of a calculus or to temporarily bypass an obstruction with a catheter. A urethrotomy may be closed primarily or left to heal by second intention depending on the condition of the urethra. When permanent diversion of urine around a distal urethral obstruction is required, or when it is likely that calculi formation will cause reobstruction, a urethrostomy is per- formed. This is a more demanding procedure in which the incised urethral mucosa must be carefully sutured to the skin without tension to create a permanent stoma. Initial Therapy for Urinary Obstruction Patients with acute urethral obstruction often develop postre- nal uremia, acidosis, and hyperkalemia. These patients are From the Department of Veterinary Chnical Sctences, College of Vetermary Medicine, The Ohio State Untversity, Columbus, OH. Address reprint requests to Daniel D. Smeak, DVM, DACVS, The Ohio State Universtty, College of Veterinary Medicme, Departmentof Veterinary Clinical Sciences, 601 Vernon L. Tharp Street, Columbus, OH 43210- 1089. E-mail: smeak.1 @osu.edu Copyrtght© 2000 by W.B Saunders Company 1096-2867/00/1501-0005510.00/0 doi"10.1053/svms.2000 7301 Decision-Making The decision to create a urethrotomy or urethrostomy, whether to consider local versus general anesthesia, and the location of the surgery depends on several factors (Fig 1). Patients that are considered stable undergo physical examination and blood workup, appropriate imaging techniques (such as contrast urethrogram, ultrasonography), and/or urethroscopy to deter- mine the cause and location of the obstruction. Corrective surgery is performed under general anesthesia to remove the lesion or to divert urine permanently (urethrostomy), if necessary, In toxic patients that are medically stabilized, first attempt to dislodge the obstruction or feed a catheter past the lesion. If this is unsuccessful, temporarily divert urine or remove the obstruction with a urethrotomy created just over or proximal to the obstruction. When the lesion cannot be removed (eg, urethral stricture) and urethrostomy most likely will be performed, I prefer to use a tube cystostomy placed under local anesthesia or try repeated cystocentesis for bladder decompression until the animal is stable enough for definitive surgical treatment. >5 General Urethrotomy Indications Urethrotomy is performed in male dogs to facilitate passage of catheters into the bladder and to remove urethral calculi just caudal to the os penis or, more rarely, the ischlal arch that cannot be retrograde hydropropulsed into the bladder. For calculi that can be dislodged and flushed back into the bladder, a cystotomy is always preferable to urethrotomy to avoid the risk of postoperative urethral stricture. In rare instances, if cystoscopy is not available, urethrotomy may be used for access to the urethral lumen to biopsy or expose obstructive Clinical Techniques in Small Animal Practice, Vol 15, No 1 (February), 2000 pp 25-34 25