In collaboration with the American College of Veterinary Surgeons

Endoscopic Removal of Urinary Calculi ❯❯ Clarence A. Rawlings, DVM, PhD, DACVSa The University of Georgia

espite advances in the prevention 7-kg female dog can usually accommodate and management of urinary cal- a 2.7-mm cystoscope with a 14.5-Fr sheath. Dculi, calculus removal remains a These dimensions should allow a calcu- At a Glance common need in small animal practice. In lus 6 to 7 mm in diameter to be removed Patient and Technique fact, changes in calculus management have through the . In male dogs, tran- Selection increased the percentage of calculi that are surethral removal is limited to much smaller 1 Page 476 difficult to manage medically. Endoscopic calculi because the stones must traverse the Preoperative Patient techniques that reduce the need for calcu- os penis region of the urethra. Calculi in lus removal by traditional and male cats can be removed by laparoscopic- Management cystotomy have been developed. In my assisted , but the urethra is too Page 477 experience, most cystic and urethral cal- small for current transurethral cystoscopy Transurethral culi can be removed by transurethral or techniques. The ability to endoscopically Cystoscopy laparoscopic-assisted cystoscopy. These remove cystic and urethral calculi has Page 478 techniques decrease trauma to and largely replaced the need for hydropulsion Laparoscopic-Assisted contamination of the abdomen. in female dogs. Cystoscopy also improves the ability to examine the Transurethral cystoscopic calculus removal Page 479 for disease and the pres- in female dogs has been enhanced in some Intraoperative ence of more calculi. specialty hospitals by cystoscopic lithotrip- and ­s y . 3–11 As with basket removal of calculi Cystoscopy Patient and Technique Selection from the lower urinary tract, can Page 482 Nearly all calculi in female dogs and cats be more widely used in female dogs than Other Minimally can be removed by either transurethral male dogs. Cystic lithotripsy is indicated Invasive Techniques cystoscopy or laparoscopic-assisted cystos- for calculi that are too large to be removed Page 484 copy, in my experience. Most male dogs cystoscopically with baskets. The current Postoperative Patient can be treated with laparoscopic-assisted contraindications to lithotripsy are large cystoscopy.2 Transurethral cystoscopy is calculi and high numbers of calculi in rela- Management Page 484 preferred for female cats and dogs because tion to the operator’s expertise. Trauma and it is less invasive than laparoscopic-assisted time required to fragment and remove large techniques; however, calculi must be small or multiple calculi can be excessive during enough to be pulled through the urethra if inappropriate lithotripsy. transurethral cystoscopy is to be successful. Laparoscopic-assisted cystoscopy through aDr. Rawlings discloses that he Size criteria are continually being modi- one or two small abdominal incisions has has received financial support fied, but I have found that in female cats proven to be an effective and relatively simple from Biovision, Covidien, Ell- and dogs, calculi can be removed that are way to remove calculi from female and male man International, Endoscop- 2–12 ic Support Services, and Karl twice the diameter of the largest cystoscope dogs and cats. The primary contraindica- Storz Veterinary Endoscopy. appropriate for the patient. For example, a tion is the presence of stones several centi-

476 Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com meters in diameter that require removal through a long abdominal incision. Although cystoscopy can still be used to examine the urinary sys- tem after removal of larger calculi, the longer incision might as well be for a traditional lapa- rotomy and cystotomy. The presence of a very large number of smaller calculi can discourage Surgical Views is a collaborative series between some endoscopists, but the use of lavage and the American College of Veterinary Surgeons suction permits removal of larger numbers of (ACVS) and Compendium. stones during laparoscopic-assisted cystoscopy. In the hospitals in which I practice, tradi- Upcoming topics in this series include vacuum- assisted wound closure, conventional foreign tional laparotomy and cystotomy are usually object removal, and suspensory ligament rupture. reserved for patients with very large calculi or All Surgical Views articles are peer-reviewed by those requiring other complex abdominal pro- ACVS diplomates. cedures, such as . However, some additional procedures are better performed To locate a diplomate, ACVS has an online directory that during than by laparotomy. An includes practice setting, species emphasis, and research example would be a , for which lap- interests (acvs.org/VeterinaryProfessionals/FindaSurgeon). aroscopy is minimally invasive and can be used to obtain multiple tissue samples from selected ing techniques are commonly used, but urinary sites as well as a bile sample for culture. contrast procedures seem to be less frequently Some subspecialists successfully remove employed. Ultrasonography by an experienced calculi from the and bladder using ultrasonographer is particularly useful for moni- advanced endourologic techniques.2–11 These toring dogs with recurrent calculi, especially techniques are widely performed in people; when the calculi are small. in the veterinary setting, they have been most If present, prerenal and postrenal azotemia commonly applied in larger female dogs. or uremia should be addressed before calcu- Lithotripsy and endoscopic removal of cal- lus removal in all but the most urgent cases of culi from the kidneys and ureters are typically obstruction. Confirmed renal dysfunction may referral procedures, in contrast to the endo- require modification of the plan for calculus scopic techniques for transurethral and laparo- removal. In patients with a preexisting urinary scopic-assisted cystoscopic procedures, which have been performed by general practitioners FIGURE 1 trained in endoscopy.

Preoperative Patient Management Patient evaluation is directed toward deter- mining renal function, the presence of urinary tract , systemic organ function, and the number, size, and distribution of calculi. Tests include a complete count, serum chemistry profile, urinalysis, and urine cul- ture. Abdominal radiography is indicated to determine the size, number, and distribution of radiopaque calculi. Radiopaque calculi are com- posed of struvite, silica, and calcium oxalate; of Chris Herron Courtesy Calculus removal from the urethra, bladder, proximal , and renal more radiolucent calculi contain urate, uric acid, pelvis frequently involves a 2.7- or 1.9-mm cystoscope with a basket and cystine. Abdominal ultrasonography is pre- retrieval instrument. The basket retrieval instrument is passed through the ferred to radiography for detecting radiolucent cystoscope’s operating channel, and the basket is kept inside the channel until a calculi and helps obtain more information stone is visualized through the scope. To capture the stone, the basket is advanced about renal structure and function. Both imag- through the end of the channel. Once around the calculus, the basket is tightened.

CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians® 477 FIGURE 2 Transurethral cystoscopy in a 6-year-old spayed schnauzer. The patient had a 3-week history of repeated straining to void and inappropriate voiding inside the house. The dog had previously had a cystotomy to remove calcium oxalate calculi.

Radiograph showing a urethral calculus Endoscopic view of the larger calculus The removed calculi were 6 mm in (circle). Urine culture results at the time at the outflow tract, just before being diameter. Despite attempts to medically of radiography had no bacterial growth. snared with the basket retrieval device. prevent recurrence, clinical signs devel- Using radiography and ultrasonography, oped, and more calculi were diagnosed the dimensions of the calculi were mea- using ultrasonography and removed by sured to determine whether transurethral cystoscopy. cystoscopy could be used to remove them. The dog weighed 10 kg, and the largest calculus appeared to be 5 mm in diameter. Courtesy of Clarence A. Rawlings, DVM, PhD, DACVS PhD, DVM, Rawlings, A. of Clarence Courtesy

tract infection, culture and administra- using this method should be no more than twice tion should be attempted before emergency relief the diameter of the largest cystoscope that can of urinary obstruction. In patients with recurrent be placed in the urethra. Commonly used cysto- urinary tract , collection of a bladder scope sizes are 1.9 mm for female cats and dogs mucosal sample for culture should be consid- weighing <5 kg, 2.7 mm for female dogs between ered during calculus removal. Regardless 5 and 15 kg, and 3.5 or 4.0 mm for larger female of the protocol used to control urine con- dogs (Figure 1). The two smaller cystoscope sizes to learn tamination of the abdomen, the risk of can be used to retrieve calculi in nearly all female more contamination dictates the use of antibi- dogs. A 1.9-mm cystoscope and a basket retrieval otics during cystoscopy and laparoscopic- instrument have been used to remove calculi dur- assisted cystoscopy. ing cystoscopic examination of the urethra and For descriptions of other bladder of male cats after perineal urethrostomy. laparoscopic techniques, Transurethral Cystoscopy It is not uncommon during transurethral see “Laparoscopic-Assisted Calculus removal using a stone basket is less cystoscopic calculus removal to find lesions and Laparoscopic Prophylactic Gastropexy: invasive than and preferred to cystotomy that may be related to recurrent urinary tract Indications and Techniques” during laparotomy or laparoscopic-assisted infections. These include strictures, transition­al (February 2009) and cystoscopy if the calculi are small enough cell carcinoma, inflammatory polyps, and per- “Techniques for for removal via the urethra. The clinician sisting cystotomy closure sutures. Laparoscopic and must be a competent and experienced cys- Basket retrieval devices with three or four Laparoscopic-Assisted toscopist to attempt calculus removal using wires are preferred (Figure 1). They should Biopsy of Abdominal a basket retrieval instrument. In general, easily fit through the operating channel of the Organs” (April 2009), available on basket removal can be attempted for cal- cystoscope. After diagnostic cystoscopy is used CompendiumVet.com. culi <3 mm in diameter in female cats and to examine the lower urinary tract and flush male dogs. In female dogs, calculi removed the bladder, the basket is passed through the

478 Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com operating channel (Figure 2). Individual tech- FIGURE 3 niques vary, but I prefer to have the bladder only mildly distended and to keep the lavage flow rate low. This practice concentrates the calculi and reduces the swirling effect that can be produced by higher flow rates. Having the patient in dorsal recumbency and tilted with the head up can also move the calculi toward the outflow tract. External abdominal manipu- lation of the bladder can be helpful. The basket is opened in the area of the cal- culi and gradually closed during cystoscopic examination. Some clinicians prefer to tighten the wires very securely around the stones. I often use less force to cradle the calculi dur- ing extraction. The basket distention helps to Courtesy of Chris Herron Courtesy gradually dilate the urethra during extraction The basic scopes used to diagnose and remove calculi are the 2.7-mm and reduces the likelihood of calculus frag- rigid cystoscope (top) and the 2.5/2.8-mm flexible fiberoptic urethroscope (bot- mentation due to basket compression. This tom). Cats and dogs weighing <5 kg frequently require a 1.9-mm cystoscope. The procedure is repeated until all the calculi are flexible scope is usually reserved for use in male dogs. removed. Vigorous flushing may be used to remove the smallest calculi. Leaving the cys- toscope sheath in the urethra with the cranial transvesicular cystoscopy require the use of a end in the outflow tract while squeezing on rigid cystoscope to examine the bladder and ure- the bladder can provide a conduit for small thra and to remove calculi. A 2.7-mm cystoscope calculi to be flushed from the bladder. is generally used, except in cats and small dogs, lithotripsy uses a holmium:YAG laser for which a 1.9-mm cystoscope is preferred. After as well as a cystoscope. Some urologists rou- calculi are removed from the bladder and out- tinely perform of calculi in the flow tract, the urethra is examined with a rigid bladder, ureters, and kidneys. Patient selection cystoscope (female dogs) or a 2.5/2.8-mm flex- is critical because the time for fracture and ible fiberoptic urethroscope (male dogs; Figure extraction can be excessive for large or mul- 3). Urethral calculi in male dogs are removed by QuickNotes tiple calculi. Candidates for laser lithotripsy either retrograde flushing or a basket retrieval Endoscopy are patients that do not meet the criteria for device passed beside the urethroscope during improves the abil- laparoscopic-assisted cystoscopy. Urethrostomy other forms of endoscopic calculi removal. In ity to examine the general, laser lithotripsy appears to require a is rarely required to remove calculi obstruct- longer time for removal of calculi while result- ing the urethra just caudal to the os penis. urinary system for ing in a similar percentage of retained calculi Laparoscopic-assisted cystoscopy has been com- disease and the as traditional cystotomy.10,11 Clinical studies of bined with other laparoscopic procedures such presence of more minilaparotomy cystotomy have fewer patients, as or laparoscopic-assisted gastroin- calculi. but this technique appears to ensure a very testinal foreign body removal. favorable percentage of calculi removal.2,12 In laparoscopic-assisted cystoscopy, the lap- aroscope trocar is placed on the midline just Laparoscopic-Assisted Cystoscopy caudal to the umbilicus to enable identification Cystoscopy via minilaparotomy was initially of the apex of the moderately distended urinary reported as laparoscopic-assisted cystoscopy.2 bladder. A second trocar, through which a 5-mm Laparoscopic assistance requires a laparoscope Babcock forceps can be passed to grasp the apex and two trocars, in contrast to the more recently of the bladder, is then placed (Figure 4). The reported technique of percutaneous cystolitho- second trocar site is on the midline for female tomy, also called keyhole transvesicular cys- dogs, cats, and some male dogs, depending on tourethroscopy.12 Both laparoscopic-assisted and the position of the prepuce in relationship to the

CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians® 479 FIGURE 4 Laparoscopic-assisted cystotomy technique.

QuickNotes Calculi can be removed with a Setup for laparoscopic-assisted cystotomy. The moni- The cranial margin of the bladder is variety of instru- tor is to the rear of the patient. A right-handed surgeon grasped and lifted to an extended trocar ments, depending stands to the patient’s left (top of illustration). The urinary incision site. Insufflation pressure is on the size and bladder is mildly distended. decreased when the bladder is lifted. number of stones.

The bladder is secured to the patient, and a minicysto- tomy is made. A rigid cystoscope and retrieval devices are passed through the minicystotomy.

Calculi can be quickly grasped by placing a retrieval forceps alongside the cystoscope. Basket retrieval devices can also be used. All illustrations © The University of Georgia; photograph courtesy of Chris Herron courtesy photograph University of Georgia; The © All illustrations

apex of the bladder. In most male dogs, the sec- just sufficient to secure it to the abdominal wall. ond trocar site is placed laterally (e.g., on the A variety of techniques can be used to keep the left side for a right-handed surgeon). The apex bladder firmly secured to the abdominal wall of the bladder is grasped with the forceps and and prevent urine contamination of the peri- lifted to the trocar site, which is extended as toneal cavity. In the most common technique, a minilaparotomy (Figure 4). If any bladder four quadrate attachments with interrupted lumen is cranial to the trocar site, inspection cruciate sutures are placed, and their long tags and removal of calculi from the cranial pouch are secured to drapes. Some surgeons prefer to of the bladder becomes difficult. The bladder is place a temporary continuous suture between not exteriorized, with the minilaparotomy being the bladder and skin.

480 Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com FIGURE 5 Equipment for intraoperative nephroscopy to remove renal calculi.

Intraoperative nephros-­ ­copy to remove renal calculi is similar to . A grasp- ing device, such as an alligator forceps, is passed beside the cystoscope. Practice with inanimate models can markedly improve calculus retrieval skills.

Intraoperative nephros­ -­ copy using a basket retrieval device can be an effective alternative, especially for calculi lodged in the proximal area of the ureter. QuickNotes Practice with inani- mate models can markedly improve Illustrations © The University of Georgia Georgia of University The © Illustrations calculus retrieval skills. Once the bladder is securely sealed to the smaller ones can be flushed from the bladder abdominal wall, a small cystotomy is performed using urethral flushing and surgical suc- and a rigid cystoscope (1.9 mm for cats and small tion. The cystoscope is then advanced through dogs and 2.7 mm for larger dogs; Figure 4) is the urethra in female dogs and cats. A 2.5- to 2.8- placed into the bladder. The bladder is lavaged mm flexible urethroscope can be passed from in a fashion similar to that for trans­urethral cys- the bladder to the os penis in most male dogs toscopy. Some clinicians prefer to have a urethral and through the os penis in male dogs larger catheter as an additional infusion source. The than 12 to 15 kg. Only the cranial portion of the bladder and entire urethra of female dogs and urethra is examined in male cats. It is common the prostatic urethra of males are examined with to watch a urethral catheter pass around irregu- the rigid cystoscope. Calculi can be removed larly shaped calculi without feeling resistance with a variety of instruments, depending on to the catheter’s passage. In my experience, the size and number of stones. Alligator for- urethral strictures just proximal to the os penis ceps, 5-mm Babcock forceps, and arthroscopic from prior calculi obstruction and trauma are grasping forceps are passed parallel to the cys- common in dogs. Knowledge of such strictures toscope to grasp and retrieve calculi (Figure can justify a scrotal urethrostomy. After calculus 4). Another removal technique is to use a wire removal and flushing, the cystotomy is closed basket retrieval instrument passed through the in a single layer, using an appositional suture operating channel of the cystoscope. The entire pattern, avoiding the mucosa. Greater omentum assembly of cystoscope and forceps or basket is sutured to the bladder closure. retrieval device is removed with each stone and Keyhole transvesicular cystourethroscopy replaced into the bladder to retrieve the next. is performed in a similar fashion except that Once the larger calculi are removed, some laparoscopy is not used and the apex of the

CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians® 481 FIGURE 6 Removal of renal calculi from a 12-year-old castrated Maltese.

Radiograph showing the renal calculi One of the calculi is examined during The removed calculi. Recovery was (arrows). These calculi were diagnosed 6 nephroscopy. uncomplicated. months before cystotomy to remove them. Courtesy of Dr. Rawlings of Dr. Courtesy

bladder is grasped with surgical instruments is dilated. Calculi have been removed by using passed through a small laparotomy.12 Again, it an alligator forceps placed beside a 30° scope is critical that the cranial portion of the bladder or through a separate puncture to achieve tri- be selected to avoid having bladder cranial to angulation or by using a basket retrieval device the cystotomy site. The remainder of the proce- placed through the operating channel of the dure is similar. Both laparoscopic-assisted and cystoscope (Figures 5 and 6). Unlike neph- transvesicular cystoscopy techniques have been rotomy, this minimally invasive retrieval of reported as being effective in the hands of the renal calculi using a scope placed through the technique developers.2,12 Both allow the same renal pelvis does not require transient occlu- excellent examination of the lower urinary tract, sion of renal vessels. The scope can also be limit bladder trauma, limit urine contamination passed through the proximal part of the ure- of the abdomen, and should increase the likeli- ter. When removing calculi endoscopically, the QuickNotes hood of complete removal of calculi. renal recesses must be thoroughly examined Urinary calculi to ensure complete stone removal. The often recur. Intraoperative Nephroscopy and perforations are closed by firmly apposing their Cystoscopy sides or by placing small sutures in the capsule Rigid endoscopy during an open laparotomy across the perforation. The scope can be used causes minimal insult to the urinary system to differentiate between intraluminal calculi from the renal pelvis to the urethra,13 improves and mural calcification. I have also used an lighting, and increases magnification much arthroscope to examine dilated ureters when more effectively than magnifying loupes and removing ureteral calculi or performing a neo- diode head lights. The optical space within cystostomy or ureterotomy. the lumen of the renal pelvis and ureters is Cystoscopes and ureteroscopes have also obtained as for cystoscopy, using saline infu- been used to examine the lumen of the blad- sion. The most frequent intraoperative use der and urethra during traditional laparotomy. of endoscopy is to examine the renal pelvis Calculus removal via laparotomy in these and recesses when removing renoliths.13 The cases usually involves major procedures such approach is similar to arthroscopy, with a as nephrectomy or removal of stones from the scope being placed through a puncture in the kidney or ureter, which are not amenable to greater curvature (lateral margin) of the kidney. less invasive techniques. The cystoscope can Penetration of the pelvis is easy when the pelvis be passed through a minicystotomy before a

482 Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com cystotomy is performed, for example, calculi are not present. Appropriate fluid to determine the precise area before management helps maintain renal func- resection of an inflammatory .14 tion and flush residual blood and calculi fragments. Although laparoscopic pro- Other Minimally Invasive Techniques cedures are less invasive than traditional Calculus removal treatments for dogs , pain medication is routinely and cats are gradually being adapted used. Typical protocols include adminis- from those used for people. Laser tering opioids during the initial recovery and electrohydraulic lithotripsy are period and either NSAIDs or opioids for already being used for cystic calculi the first few days after calculus removal. in dogs and cats.3–11 Laser lithotripsy Bupivacaine can be infused into the and ureteral stenting during ureteros- urethra for additional transient analgesia. copy are routinely used for ureteral Dietary management to reduce calculus calculi in people; however, size is a formation is usually delayed until the limiting factor in small animals, espe- patient is fully recovered and the final cially cats and small dogs. In people, calculi analysis obtained. Nutritional renal calculi are removed by percuta- therapy soon after surgery should focus neous nephrolithotomy, ureterolitho- on supporting early healing. tomy, and cystolithotomy, typically Urinary calculi often recur. Patients involving lithotripsy, basketing, and with a history of calculus removal must flushing. Finally, extracorporeal shock be closely monitored by the owner and wave lithotripsy is an alternative to veterinarian. Those with a history of reduce calculus size so that urine flow must have reg- can flush the fragments.13,15 ular urinalysis and, if indicated, urine cultures. When feasible, dietary man- Postoperative Patient Management agement should be considered. Dogs Case management must be directed to and cats in which calculi recur despite the patient’s needs. At least one lateral good medical management are candi- radiograph should be taken after calcu- dates for ultrasonography studies every lus removal while the patient is anesthe- 4 to 6 months. Radiography can also be tized to ensure that residual radiopaque considered for radiopaque calculi.

References 1. Ling GV, Thurmond MC, Choi YK, et al. Changes in 9. Defarges A, Dunn M. Use of electrohydraulic litho- proportion of canine urinary calculi composed of calci- tripsy in 28 dogs with bladder and urethral calculi. J um oxalate or struvite in specimens analyzed from 1981 Vet Intern Med 2008;22(6):1267-1273. through 2001. J Vet Intern Med 2003;17:817-823. 10. Bevan JM, Lulich JP, Albasan H, Osborne CA. 2. Rawlings CA, Barsanti JA, Mahaffey MB, Canalis C. Comparison of laser lithotripsy and cystotomy for Use of laparoscopic-assisted cystoscopy for removal the management of dogs with urolithiasis. JAVMA of calculi in dogs. JAVMA 2003;222:759-761. 2009;234:1286-1294. 3. Senior DF. Electrohydraulic shock-wave lithotripsy 11. Lulich JP, Osborne CA, Albasan H, et al. Efficacy for experimental canine struvite disease. and safety of laser lithotripsy in fragmentation of uro- Vet Surg 1988;22:213-219. cystoliths and urethroliths for removal in dogs. JAVMA 4. Adams LG, Senior DF. Electrohydraulic and extra- 2009;234:1279-1285. corporeal shock-wave lithotripsy. Vet Clin North Amer- 12. Runge JJ, Mayhew P, Berent A, et al. Keyhole ica Small Anim Pract 1999;29:293-302. transvesicular cystourethroscopy for the retrieval of 5. Lane IF. Lithotripsy: an update on urologic applica- cystic and urethral calculi in dogs and cats. 43rd Annu tions in small animals. Vet Clin North Am Small Anim Meet Am Coll Vet Surg 2008. Pract 2004;34(4):1011-1025. 13. McCarthy TC. Otheroscopies. In: McCarthy TC, ed. 6. Davidson EB, Ritchey JW, Higbee RD, et al. Laser Veterinary Endoscopy for the Small Animal Practitio- lithotripsy for treatment of canine uroliths. Vet Surg ner. St Louis: Elsevier Saunders; 2005:423-445. 2004;33:56-61. 14. Rawlings CA. Resection of inflammatory polyps in 7. Grant DC, Were SR, Gevedon ML. Holmium:YAG la- dogs using laparoscopic-assisted cystoscopy. JAAHA ser lithotripsy for urolithiasis in dogs. J Vet Intern Med 2007;43:1-5. 2008;22(3):534-539. 15. Block G, Adams LG, Widmer WR, et al. Use of ex- 8. Adams L, Berent A, Moore A, Bagley D. Laser litho- tracorporeal shock wave lithotripsy for treatment of tripsy for the removal of uroliths in 73 dogs. JAVMA nephrolithiasis and ureterolithiasis in five dogs. JAVMA 2008;232(7):1026-1034. 1996;208(4):531.

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