Symposium on Surgical Techniques

Surgical Treatment of Ectopic Ureters Guy B. Tarvin, D.V.M.*

The ureters are small fibromuscular tubes (0.6 to 0.9 em in diameter) which act as conduits for urine between the kidneys and urinary bladder. The active component of ureteral function consists of peristaltic waves that originate from the renal pelvis and act to propel urine along the length of the ureter. Spatial anatomic relationships at the ureteral termination are important passive components. The ureters normally end at the trigone of the bladder. Urine then collects in the bladder and is held there until a suitable time when micturition is initiated. If the ureters end distal to the bladder, this phase of urine excretion is frequently lost and the animal constantly dribbles urine. Another important anatomic relationship exists as the ureter courses through the bladder wall. After entering the serosal surface, the ureter travels several centimeters intramurally and submucosally before entering the lumen at the trigone. As the bladder fills with urine, intramural pressure increases and acts to "close" the ureters and prevent vesiculoureteral reflux and ascending infections. One condition which will upset these latter passive functions is ureteral ectopia. Ureteral ectopia is a rare congenital anomaly in which there is an abnormal termination or origin of the ureters. Abnormal termination of the ureter into the neck of the bladder, urethra, uterus or vagina is most commonly seen in veterinary cases. The exact etiology for ureteral ectopia has not been determined, but various nutritional deficiencies (such as vitamin A) in gestating animals have been incriminated. 7 The pathogenesis, however, is more dearly understood. Embryologically, the ureters develop from the metanephric duct system. This duct system arises from the dorsal surface of the distal end of the mesonephric duct. As the embryo develops, the metanephric ducts migrate laterally and cranially to terminate on *Assistant Professor of Surgery. University of Illinois Veterinary Medical Teaching Hospital, Urbana, Illinois

Veterinary Clinics of North America: Small Animal Practice- Vol. 9, No. 2, May 1979

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a structure that later becomes the trigone. Abnormal origin or migration of the metanephric duct system results in ectopic termination of the ureters. Also, of clinical importance is the close relationship between the development of the metanephric duct system and the development of other structures arising from the urogenital sinus (i.e., kidneys, bladder, trigone, urethra, vagina, etc.). 7 For this reason, ureteral ectopia may not be an isolated event and may be seen in corBunction with other anomalies such as cystic and renal hypoplasia and bladder agenesis. The incidence of ectopic ureters in veterinary medicine is not known; however, the disease is reported most commonly in female dogs. 1 • 2 • 4 • 6 • 8 • 9 There is no satisfactory medical therapy for this condition and, since it is a physical malformation, surgical intervention is the treatment of choice. With this as background, the problem of ureteral ectopia will be discussed with particular emphasis on surgical techniques and management.

DIAGNOSIS The most prominent clinical sign in an affected female is continual dribbling of urine. They may be present from birth and may be associated with persistent wetness of the perivulvar hair and skin with subsequent urine irritation and excoriation of the area. Other causes of urinary incontinence such as cystitis, neurogenic factors, hormonal imbalances, urethral abnormalities, psychological dribbling (puppy hysteria), neoplasia (i.e., involving the bladder trigone), and other congenital anomalies should be considered in the differential diagnosis and eliminated. Examination of the vagina through a speculum (vaginoscopy) may be helpful in that the ectopic ureteral orifice may be visualized. If possible, the ectopic orifice can be catheterized with a radiopaque flexible catheter and a retrograde pyelogram performed to confirm the diagnosis. Very often, however, the veterinarian is dealing with young small animals and the ectopic ureteral orifice cannot be located by these techniques, and other diagnostic methods must be utilized. One of the best methods of confirming the diagnosis of ectopic ureter is via excretory urography (intravenous pyelogram). Excretory urography provides useful information about the status of the renal pelvis, ureter size, and termination of the ureters (Figs. 1, A and B). It may also be useful in assessing urinary bladder size and distensibility, but this is best demonstrated by contrast cystography. Exact location of the ureteral orifice is not always possible by excretory urography as a result of masking of the orifice by the presence of contrast material in the bladder or poor excretion by an ipsilateral hypoplastic kidney. 5

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Figure l, A, Radiograph diagnostic for ectopic right ureter in a 6 month old female malamute. B , The dilated ureter (b) leaves the r ight kidney (a) to terminate ectopically distal to the ur inary bladder (c).

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Other means of confirming the diagnosis of ectopic ureter include retrograde urography and exploratory laparotomy.

PREOPERATIVE CONSIDERATIONS A thorough physical examination of all systems should be performed to assess the general overall health of the animal and ascertain whether any other congenital anomalies exist. Minimal blood work in the healthy animal should consist of blood chemistries that assess kidney function (BUN or serum creatinine) and a complete blood count. Urinalysis to assess kidney function along with a culture and sensitivity of the urine are also essential. Since the ectopic ureter has no functional valve at its orifice, urine reflux and persistent infection are common. Whenever possible, appropriate antibiotic therapy should be instituted to clear the infection prior to ureteral surgery. The surgeon should be prepared to reculture the bladder and urine at the time of surgery.

SURGICAL CONSIDERATIONS Numerous surgical techniques for correction of ectopic ureters are available to the veterinary surgeon, and his choice is dependent on the factors involved in each individual case. In unilateral ectopic ureter with normal function of the other kidney, ureteronephrectomy as described elsewhere may be considered. 3 V esiculoureteral transplants can be attempted if: there is normal renal function on the side of the ectopic ureter; bilateral symptomatic ectopic ureters are present; or there is hypofunction of both kidneys and a unilateral ureteronephrectomy would compromise the remaining kidney. When attempting ureteral surgery, the surgeon should be aware of the following problems with ureteral healing. 4 The ureter responds poorly to overstretching, therefore, tension at anastomotic sites should be avoided. Second, although the ureter is capable of tremendous regenerative powers for longitudinal defects, it tolerates cross-sectioning poorly and stricture of anastomotic sites may be a sequela. The last important aspect is that an excessive number of sutures at anastomotic sites is poorly tolerated as they may further compromise blood supply to the ureters via strangulation and thus delay healing.

Technique A posterior ventral midline abdominal approach is used. The incision should extend from a point midway between the xiphoid and umbilicus to the pubis. The intestinal coils are packed off with salinemoistened laparotomy packs. Balfour abdominal retractors are placed

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in the incision to facilitate exposure, and the kidneys, ureters, and urinary bladder are then examined. The affected ureters(s) are identified and carefully traced distally. The ureter need only be traced until there is sufficient length to allow for transplantation without tension on the sutures. It is severed at this point and the distal remaining segment is oversewn or transfixed with 3-0 chromic catgut. During the mobiHzation of the ureter, atraumatic technique is essential in preventing further damage to the ureter's blood supply. It is also preferable to use stay sutures and not instruments to handle and manipulate the ureter, as the latter will crush tissue needlessly. At this time the stay sutures are placed in the distal end of the ureter to be transplanted (Fig. 2) and the free end of the ureter packed off to prevent peritoneal contamination. The transplant site is then prepared. A stay suture of 2-0 silk is attached to the apex of the bladder, which is exteriorized and packed off. A ventral cystotomy incision is made extending from the apex to the level near the trigone and stay sutures placed in the lateral edges of the incision to facilitate visualization of the bladder lumen. The bladder is then retracted posteriorly in preparation of the transplant site.

Figure 2. A midline abdominal incision has been made exposing the ureters, urinary bladder, and the kidneys. The ectopic ureter has been located, severed at its distal end (arrow), and stay sutures placed in the end to be transplanted.

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To prevent vesiculoureteral reflux, the ureter must course a sufficient distance intramurally or submucosally through the bladder wall. This is accomplished by creating a submucosal-intramural tunnel in the following manner. A small incision is made in the serosa and the tunnel is created using a curved mosquito forceps (Fig. 3.). This tunnel should open near the normal ureteral orifice on the mucosal surface. In order to provide adequate valvular action, the ratio of tunnel length to ureteral orifice diameter should be 5 to 1 (Fig. 4B). When the tunnel is properly formed, the mucosa over the tips of the forceps is incised. The curved forceps are removed, and reintroduced and passed through the tunnel from the mucosal to the serosal side. The ureter to be. transplanted is removed from the laparotomy packs and the ends of the stay suture are grasped in the tips of the hemostat. The stay suture and ureter are gently drawn through the tunnel (Fig. 4A). The distal end of the ureter to be transplanted is spatulated in order to increase the orifice diameter (Fig. SA) and sutured to the mucosal surface of the bladder with 4 to 6 sutures of 3-0 or 4-0 chromic catgut or Dexon (Fig. 5B). Absorbable suture material is preferred since a nonabsorbable material remaining in the bladder lumen may act as a nidus for infection and calculi formation. Again, it

Figure 3. The urinary bladder has been exteriorized and incised on its ventral aspect. The curved forceps is inserted through a small incision made in the serosa to form a tunnel.

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8 Figure 4. A, Cross sections of bladder wall. Pulling of the ureter through the subserosal-intramural tunnel. The hemostat is inserted from the mucosal side of the bladder wall and through the tunnel. The stay sutures are then grasped in the tips of the hemostat, and gentle traction is applied until the ureter has been pulled to the mucosal side of the bladder. B, The ureter in place for suturing. The tunnel length to ureteral orifice diameter ratio should be approximately 5: 1.

should be stressed that gentle handling of the ureters while suturing is of utmost importance in increasing the success of a ureteral transplant. Once secured in place, the ureter(s) can be stented with a No. 4 or 5 French flexible urinary catheter. The catheter is brought out through the urethra and secured just inside the vulvar lips of the wall of the vagina with a suture of 2-0 nylon. Closure of the urinary bladder and abdominal incisions is done in a routine matter.

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Surgical treatment of ectopic ureters.

Symposium on Surgical Techniques Surgical Treatment of Ectopic Ureters Guy B. Tarvin, D.V.M.* The ureters are small fibromuscular tubes (0.6 to 0.9...
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