SURGERY


rectal tear,1 perforation of the urinary bladder or urethra,1,5 unsuccessful attempts to fragment cal- culi,16 and an inability to remove all fragments from the bladder.1,6,11 Reported postoperative complica- tions include peritonitis, fever and urethritis,1 cystitis,1,5 retained fragments causing urethral ob- struction,5 urethral stricture,2 and recurrence.1,11 In light of the difficulties often encountered while attempting successful, complete removal of cystic calcui in the standing sedated horse, and the many complications which can be encountered, the follow- ing technique was developed. A laparoscopic spec- imen retrieval pouch is utilized to contain and stabilize cystic calculi during fragmentation and fa- cilitate safe removal of calculi. Further, the pouch protects the urinary bladder and urethra from iat- rogenic trauma during removal of intact calculi or following fragmentation of calculi.


2. Materials and Methods


For horses diagnosed with cystic calculi, a thorough physical examination, followed by ultrasonographic and endoscopic imaging should be performed. Ul- trasonographic examination should include transcu- taneous examination of the left and right kidneys, followed by transrectal examination of the urinary bladder, left kidney, and left and right ureters to determine the approximate size of the cystolith, as well as identify other uroliths or gross abnormalities affecting the urinary tract. Preoperative serum biochemical analysis (CBC) should also be per- formed, as additional abnormalities identified dur- ing physical examination, diagnostic imaging or hematologic evaluation may guide treatment and have a substantial impact on prognosis. In preparation for surgery, an intravenous jugular catheter should be placed, and horses administered procaine penicillin G (22,000 U/kg IM), gentamicin sulfate (6.6 mg/kg IV), and flunixin meglumine (1.1 mg/kg IV), and tetanus toxoid. Horses are re- strained in standing stocks and a loading dose of detomidine hydrochloride (0.01–0.02 mg/kg) admin- istered intravenously. Sedation can be maintained with a continuous intravenous infusion of detomi- dine (0.02–0.05 mg/kg/h) or through additional bo- luses of detomidine to effect. Caudal epidural anesthesia should be performed at this time using 2% lidocaine hydrochloride solution (0.2 mg/kg), which desensitizes the perineal region, and facili- tates relaxation of the bladder and urethra. The rectum should be evacuated of feces, and the perineum aseptically prepared for surgery. A flex- ible urinary catheterb can now be positioned in the urethra, and a standard PU19 performed to gain access to the urinary bladder in geldings. PU is begun by making an approximately 8-cm longitudi- nal midline skin incision in the perineum, beginning 2 to 4 cm distal to the anus and extended ventrally to the level of the ischial arch. Dissection is then directed through the subcutaneous tissues, and the paired retractor penis muscles and bulbospongiosis


Fig. 1. Laparoscopic retrieval pouch introducer and detached polyurethane retrieval pouch displaying a cystic calculus success- fully removed intact. The depth of pouch allows for exterioriza- tion of its opening following containment of calculi, facilitates manipulation, stabilization, and when necessary, fragmentation of calculi.


muscle sharply divided. A self-retaining Weitlaner retractor helps to facilitate visualization. The inci- sion is continued through the corpus spongiosum penis to expose the caudal aspect of the urethra, and a longitudinal incision made directly over the in- dwelling urinary catheter into the urethral lumen. Now the urinary catheter can be removed and a flexible 1-meter endoscope can be directed through the PU in geldings or transurethrally in mares to allow visualization of the urinary bladder. An evaluation of the urinary bladder should com-


mence, and once the calculus has been observed, the laparoscopic specimen retrieval pouchc can be intro- duced alongside the endoscope, and the pouch de- ployed. The calculus is manipulated into the pouch by sweeping the mouth of the pouch down one side of the bladder, along the floor to contact the calculus and up the contralateral wall which causes the cal- culus to roll into the pouch. This maneuver may take a few attempts to be successful. The pouch is closed by placing traction on the purse string at- tached to the pouch, and the introducer is discarded. Before attempts are made to manipulate the calcu- lus within the pouch, N-butylscopolammonium bro- mide (0.3 mg/kg IV) can be given to further relax the bladder and urethra. Sterile lubricating jellyd with 2% lidocaine solution is infused into the urinary bladder by use of a 60-mL syringe and mare insem- ination pipette, and traction can be placed on the purse string to exteriorize the mouth of the pouch. Once partial exteriorization is achieved, attempts


can be made to remove the calculus intact by placing traction on the pouch (Fig. 1). For horses in which this is not possible, lithotripsy of the calculus can be pursued. The author prefers pneumatic radial shockwave lithotripsye or manual calculus crush- ing with Knowles uterine forcepsf through the opening of the pouch. Caudal traction placed on the edges of the pouch by an assistant is essential to stabilize the calculus at the trigone of the urinary bladder (Fig. 2). Periodic lavage of the lumen of the pouch flushes out dislodged fragments. Lithotripsy is continued until the calculus is reduced in size to a


AAEP PROCEEDINGS  Vol. 64  2018 397


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