Resection of Inflammatory Polyps in Dogs Using Laparoscopic-Assisted Cystoscopy

Clarence Alvin Rawlings

doi:10.5326/0430342

Introduction

Surgery is commonly performed on the urinary bladder for removal of calculi, biopsy of masses, redirection of ectopic ureters, and evaluation of the source of hematuria.¹^,² Traditionally, these procedures have been performed by cystotomy during laparotomy via an incision from the pubis to the umbilicus.² A ventral cystotomy produces trauma to the bladder and possible peritoneal contamination with urine. The ability to examine the inside of the bladder for lesions and calculi is reduced when the cystotomy incision produces hemorrhage, the bladder is collapsed, the mucosa is folded, or the mucosa is edematous.

A minimally invasive alternative to cystotomy for calculi removal is laparoscopy with cystoscopy.³ The main advantage of laparoscopy is that it provides excellent images of the outside of abdominal structures, while cystoscopy provides equally good images of the inside of the bladder and urethra. Hemorrhage is minimal with laparoscopic-assisted cystoscopy, as the cystotomy incision is small and fluid infusion into the bladder clears hemorrhage from the visual site.³ Holding the bladder against the abdominal wall during cystoscopy reduces abdominal contamination by urine and lavage fluids.³ Cystoscopy can be used to confirm that all calculi have been removed and to thoroughly examine the mucosa of the bladder.³ Disadvantages of laparoscopic surgery include equipment cost and the need for veterinarian and staff training.

The purpose of this paper is to describe the removal of inflammatory polyps from the bladder in two dogs using laparoscopic-assisted cystoscopy. One dog also had a cystic calculus removed and liver biopsies taken through the two original trocar openings.

Case Reports

Case No. 1

A 7-year-old, spayed female Welsh terrier was referred with a history of vulvar discharge, increased frequency of urination, and spotting of blood. Urinary tract infections had been treated several times with various antibiotics during the previous 2 years. Oral phenylpropanolamine had not reduced the frequency of urination. An intraluminal bladder mass was found by the referring veterinarian during ultrasonography. An ultrasound-guided aspirate was performed, and cytological findings were consistent with an inflammatory polyp.

Upon presentation, a urinalysis collected by cystocentesis showed 10 to 50 white blood cells (WBC) per high-powered field. Escherichia coli that was sensitive to several antibiotics was cultured from the urine with a colony concentration >100,000/mL. A complete blood cell count and serum biochemical profile were normal. Abdominal ultrasonography identified an irregularly shaped, polyploid mass within the lumen of the apex of the bladder [Figure 1]. Plain radiographs of the abdomen and thorax were normal. Removal of the bladder mass was recommended to obtain a histopathological diagnosis and to remove the presumed cause of the recurrent urinary infections. Client consent was obtained with permission to convert to a traditional surgery if deemed appropriate by the surgeon.

Preoperatively, the dog was medicated with acepromazine^a (0.04 mg/kg intramuscularly [IM]), glycopyrrolate^b (0.01 mg/kg IM), and hydromorphone^c (0.1 mg/kg IM). Anesthesia was induced with propofol^d (4 mg/kg intravenously [IV]) and maintained with isoflurane^e in oxygen. The dog was placed in a mild Trendelenburg position that was <5° from horizontal. A laparoscopic-assisted approach to the bladder was taken for polyp removal.³ Positive-pressure ventilation at 12 breaths per minute, with a tidal volume of 12 mL/kg and an inflation pressure during inspiration of <25 cm water was provided during abdominal insufflation for laparoscopy.⁴ A 6-mm trocar cannula was inserted through the midline, 2 to 3 cm caudal to the umbilicus, by use of the open (Hasson) technique.⁵ The peritoneal cavity was distended to a maximum of 15 mm Hg with carbon dioxide via an insufflator,^f and a 5-mm laparoscope^g was passed through the cannula. The laparoscope was connected to a camera^h and a xenon light source.ⁱ A second 6-mm trocar cannula was inserted on the midline, directly ventral to the cranial margins of a moderately distended bladder. Prior to trocar placement, the skin and subcutaneous tissues over the selected site were incised. This abdominal incision was slightly longer than the planned cystotomy incision.A 5-mm laparoscopic Babcock forceps^j was used to grasp the cranioventral region of the urinary bladder [Figure 2A]. After grasping the urinary bladder with the Babcock forceps, the trocar incision was lengthened, and the bladder was lifted to the trocar site for placement of traction sutures around the intended cystotomy site.

A 2.7-mm cystoscope^k with a 30° viewing angle was placed through a small cystotomy incision into the cranioventral region of the bladder. The cystoscope was used to remove urine from the bladder and then to lavage the bladder with saline, providing a clear optical medium. The mucosal surface of the bladder was examined for lesions and calculi. When the only abnormality was determined to be a polypoid mass, the bladder was pulled through the abdominal incision [Figure 2B]. A no. 15 scalpel blade was used to resect the bladder wall containing the mass, with the incision near the base of the polyp [Figure 3]. The bladder wall was closed with a simple, continuous pattern of 3–0 polydioxanone suture^l placed in the serosal and muscular layers, avoiding the mucosa. After closure of the cystotomies and returning the bladder to the abdomen, the abdomen was reinsufflated to examine the caudal abdomen with the laparoscope and to grasp omentum. Omentum was secured to the bladder closure sites using the tags of the sutures that apposed the two cystotomy incisions. The laparoscopic trocar was removed. The mini-laparotomy and the laparoscopic trocar incisions were closed with separate layers of sutures placed in the external sheath of the rectus abdominus (simple continuous pattern with 2–0 polydioxanone suture), the subcutaneous fat (simple continuous pattern with 3–0 polydioxanone suture), and the skin (interrupted cruciate pattern with 3–0 nylon suture).

Postoperatively, the dog was treated with hydromorphone (0.2 mL subcutaneously at the conclusion of anesthesia) and IV lactated Ringer’s solution. Histopathological examination showed chronic hyperplastic cystitis and hemorrhagic polyps. These changes were consistent with chronic inflammation; there was no evidence of neoplasia. During the early postoperative period, the dog strained several times following urination when the bladder was already empty. Two days after surgery, the dog was discharged on deracoxib^m (3.2 mg/kg per os [PO] q 24 hours) and enrofloxacinⁿ (4.4 mg/kg PO q 12 hours). Eight months after surgery, no polyps were seen on ultrasonography, the dog was urinating normally, and urinalysis revealed no evidence of urinary tract inflammation.

Case No. 2

A 9-year-old, spayed female Cairn terrier was referred with a history of dysuria, pollakiuria, and hematuria related to a bladder calculus. The dog was currently on amoxicillin clavulanate^o (16 mg/kg PO q 12 hours) and was urinating normally. On physical examination, no abnormalities were palpated in the urinary tract; the body condition score was 4.5/5; multiple areas of alopecia were noted bilaterally over the trunk; and the hair coat was coarse. A complete blood cell count was normal, and the only abnormality on a serum biochemical profile was a mild increase in the alkaline phosphatase concentration (331 IU/L; reference range 13 to 122 IU/L). Cortisol concentrations were increased at baseline (8.7 μg/dL; reference range <3.0 μg/dL) and 1 hour (17.1 μg/dL; reference range 8 to 15 μg/dL) following adrenocorticotropic hormone (ACTH) (0.25 mg IM ACTH^p) stimulation. Urinalysis was normal except for well-differentiated transitional epithelium identified in the sediment. The cells were most consistent with hyperplastic urothelium, although a well-differentiated carcinoma could not be excluded. A urine culture was negative.

Multiple gravity-dependent hyperechoic foci were seen in the urinary bladder on ultrasonography. Several broadbased echogenic protrusions were also detected on the ventral wall of the bladder. Mild dilatation of the renal pelves and gravity-dependent debris within the gallbladder were also found on abdominal ultrasonography. Removal of the bladder calculi and polyp was recommended to obtain a histological diagnosis and to eliminate the presumed cause of the urinary tract signs. Based on the physical examination and laboratory findings (i.e., increased serum alkaline phosphatase and cortisol concentrations), it was also recommended that liver biopsies be obtained.

The dog was premedicated using midazolam^q (0.2 mg/kg IM), glycopyrrolate (0.01 mg/kg IM), and hydromorphone (0.1 mg/kg IM); propofol (4 mg/kg IV) was used for induction. General anesthesia was maintained with isoflurane in oxygen and supplemented with epidural administration of preservative-free morphine^r (0.1 mg/kg). The same trocar sites and approach to the bladder were used as described for case no. 1. Prior to the short cystotomy, the liver was examined, and biopsies were taken using a 5-mm laparoscopic biopsy cup forceps^s passed through the cannula located over the bladder. The edges of the liver were rounded, typical of hepatomegaly. The bladder was then grasped, and a cystotomy <1 cm long was performed to cystoscopically remove the single calculus with a 5-mm Babcock forceps [Figure 4].³ Calculus removal was verified by cystoscopy of the bladder and urethra during surgery, and a lateral radiograph after surgery. After calculus removal, the bladder was exteriorized through a 2.5-cm caudal abdominal incision, and two polyps were removed.

Histopathology confirmed that the masses were polyps covered by transitional epithelium with a few areas of ulceration. Stroma beneath the transitional epithelium was hemorrhagic from proliferation of granulation tissue and moderate infiltration of lymphocytes and plasma cells. Associated with the hemorrhage were extensive foci of hemosiderin. Analysis of the calculus was 100% calcium oxalate monohydrate. The liver biopsy showed mild accumulation of glycogen. Multiple foci of a gold-brown pigment —presumed to be biliary pigment—were seen inside the hepatocytes, mainly in the portal areas. The diagnoses were chronic polyploid cystitis, calcium oxalate calculus, and possible pituitary-dependent hyperadrenocorticism.

Postoperatively, the dog was continued on amoxicillin/clavulanate (16 mg/kg PO q 12 hours). The dog was discharged 4 days after surgery on amoxicillin/clavulanic acid and carprofen^t (2 mg/kg PO q 12 hours). At a recheck 2 weeks later, she was still mildly dysuric, but the dysuria soon resolved. At follow-up 8 months after surgery, the dog had no urinary tract signs, and a urine culture was negative.

Discussion

In the two dogs of the current report, laparoscopic-assisted cystoscopy for resection of inflammatory polyps was a relatively easy procedure that required smaller incisions to the abdominal wall and to the bladder as compared to traditional laparotomy and cystotomy.³ Cystoscopy allowed a thorough examination of the urinary bladder and urethra, with excellent definition of the polyp margins. Hemorrhage was minimal until the polyp was being resected. In case no. 2, the urinary bladder was left in the abdomen when removing the calculus to facilitate better examination of the bladder and urethra. The same two trocar sites were used for the liver biopsies.

Both cases in this report were female dogs, but laparoscopic-assisted cystoscopy has also been performed in male dogs.³ Modifications for male dogs have included paramedian placement of the trocar site used to grasp the bladder, and the use of a 2.5-mm flexible scope to examine the urethra to the area of the os penis.³^,^u In small female dogs, the cystoscope can be passed from the bladder through the entire urethra and into the vestibule.

Inflammatory polyps (polyploid cystitis) are chronic inflammatory changes that can develop in dogs with recurring urinary tract infections. Resection of these polyps is recommended to help manage bladder infections and inflammation.⁶ Resection of polyps with minimal surgical margins varies from the wide margins required with neoplasia. Polyps with a small pedicle may be resected using a diode laser or a radiofrequency device passed through the operating channel of a cystoscope placed transurethrally in female dogs.^u^,^v

Conclusion

Laparoscopic-assisted cystoscopy was used to resect inflammatory polyps in two dogs and to remove a single bladder calculus. Cystoscopic images of the bladder and urethra ensured that calculus removal was complete and identified the extent of the bladder disease. Further studies are warranted to evaluate the application of this technique for other bladder disorders in dogs.

^a

PromAce Injectable; Ft. Dodge Animal Health, Fort Dodge, IA 50501

^b

Glycopyrrolate Injection; American Regent, Inc., Shirley, NY 11967

^c

Hydromorphone HCl Injectable; Baxter Healthcare Corp., Deerfield, IL 60015

^d

PropoFlo; Abbott Animal Health, North Chicago, IL 60064

^e

IsoFlo; Abbott Animal Health, North Chicago, IL 60064

^f

Electronic Endoflator; Karl Storz Endoscopy American, Goleta, CA 93117

^g

0°, 5-mm, 29-cm telescope; Karl Storz Endoscopy American, Goleta, CA 93117

^h

Image 1 camera and image processor; Karl Storz Endoscopy American, Goleta, CA 93117

ⁱ

Zenon nova; Karl Storz Endoscopy American, Goleta, CA 93117

^j

5-mm Babcock forceps; Karl Storz Endoscopy American, Goleta, CA 93117

^k

14.5-Fr. Cystoscope-Urethroscope sheath with Hopkins 30° and 2.7- mm diameter forward-oblique telescope; Karl Storz Endoscopy American, Goleta, CA 93117

^l

PDS II; Ethicon, Somerville, NJ 08876

^m

Deramaxx; Novartis Animal Health US, Inc., Greensboro, NC 27408

ⁿ

Baytril; Bayer Healthcare LLC., Shawnee Mission, KS 66201

^o

Clavamox; Pfizer Animal Health, Exton, PA 19341

^p

Cortrosyn; Amphastar Pharmaceuticals, Inc., Rancho Cucamonga, CA 91730

^q

Midazolam HCl Injectable; Baxter Healthcare Corp., Deerfield, IL 60015

^r

Duramorph; Baxter Healthcare Corp., Deerfield, IL 60015

^s

5-mm biopsy cup forceps; Karl Storz Endoscopy American, Goleta, CA 93117

^t

Rimadyl; Pfizer Animal Health, New York, NY 10017

^u

Personal observations: Rawlings CA, Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, The University of Georgia, Athens, GA 30602

^v

Personal observations: McCarthy TC, Surgical Specialty Clinic for Animals, Beaverton, OR 97005