Endoscopic Removal of Urinary Calculi ❯❯ Clarence A
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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 urethra. 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 laparotomy and male cats can be removed by laparoscopic- Management cystotomy have been developed. In my assisted cystoscopy, 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 urine largely replaced the need for hydropulsion Laparoscopic-Assisted contamination of the abdomen. Endoscopy in female dogs. Cystoscopy also improves the ability to examine the Transurethral cystoscopic calculus removal Page 479 urinary system for disease and the pres- in female dogs has been enhanced in some Intraoperative ence of more calculi. specialty hospitals by cystoscopic lithotrip- Nephroscopy and s y . 3–11 As with basket removal of calculi Cystoscopy Patient and Technique Selection from the lower urinary tract, lithotripsy 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 nephrectomy. However, some additional procedures are better performed To locate a diplomate, ACVS has an online directory that during laparoscopy than by laparotomy. An includes practice setting, species emphasis, and research example would be a liver biopsy, 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 ureters 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 infection, systemic organ function, and the number, size, and distribution of calculi. Tests include a complete blood 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 ureter, 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 antibiotic 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 infections, 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