Bladder and Ureteral Substitution and Augmentation




INTRODUCTION



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Iatrogenic harm to the urinary tract can be caused by any surgeon operating in or around the pelvis and the retroperitoneal abdominal space, with an overall incidence of 0.3% to 1.5%.1 This applies to gynecologists, general surgeons, urologists, vascular surgeons, neurosurgeons, and orthopedic surgeons.



The anatomy of the lower urinary tract and its close connection with gynecologic organs makes it vulnerable to be affected by gynecologic tumors, adjuvant local treatment such as pelvic radiation, and surgical injuries at the time of dissection. More specifically, gynecologic oncologists have to often deal with a surgical scenario that includes urinary tract involvement by tumor, inflammation and, or fibrosis. It is not rare that, during the resection of a gynecologic tumor, a decision has to be made regarding whether or not to remove a portion of the ureter, bladder, or both. Furthermore, most pelvic exenterative procedures are performed in patients who have received high doses of pelvic radiation. Typically, in such situations, total cystectomy must be performed to accomplish complete tumor removal.



The goal of this chapter is to explain the general principles and different surgical tools that a trained gynecologic oncologist has to master in order to reconstruct the urinary tract when needed. Continent and incontinent reservoirs are discussed in Chapters 11 and 12 of this book. In this chapter we will discuss the surgical procedures utilized to reconstruct the ureter as well as to enlarge or substitute for the urinary bladder after any surgical injury or after a radical resection.




URETERAL SUBSTITUTIONAND REPAIR



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Background



The urinary tract is particularly susceptible to intraoperative injury for a variety of reasons. Operating in difficult situations, such as that encountered with surgery for recurrent malignancy, extensive inflammation and bulky tumors, places the urinary tract at even greater risk. Injuries to the ureter are the most common urinary tract injuries, because the ureter is ­similar in appearance to vascular structures, is difficult to identify as a result of its close adherence to the posterior peritoneum, and can be encountered at virtually any level in the retroperitoneum and upper pelvis. When these facts are studied, along with the intrinsic difficulties with the occasional unforeseen congenital anomalies, such as ureteral duplication or retrocaval ureter, it is easy to understand how easily ureteral injury can occur. Consequently, it is essential that each surgeon operating in this region be familiar with the specific anatomy of this structure.



Ureteral injury is most commonly iatrogenic in origin. Urological surgeons are the group most frequently causing ureteric injuries particularly with the use of rigid and flexible ureteroscopy. The ureter is at greatest risk for injury from ureteroscopy at the ureterovesical junction, pelviureteric junction, and the pelvic brim. Most injuries are limited to the mucosa and easily managed by the insertion of a ureteral stent.2



The majority of significant operative ureteric injuries occur during hysterectomy procedures by gynecologists.3 Risk factors include:





  1. Gynecologic malignancy



  2. Endometriosis



  3. Pelvic inflammatory disease



  4. Pelvic organ prolapse



  5. Previous pelvic surgery




The injury usually occurs where the ureter crosses inferior to the uterine artery and may be due to transection, suture ligation, or thermal damage. Unrecognized injury occurs in up to 80% of cases. Low anterior resection and abdominoperineal resection of the colon are the most common general surgical procedures associated with ureteric injuries. The left ureter is more commonly damaged than the right due to the relation with the sigmoid mesentery. Vascular bypass surgery, mainly aortoiliac and aortofemoral, can result in injury to the mid and distal third of the ureter. Devascularization during surgery is a cause of late stricture. Finally, it is fair to conclude that gynecologic oncologic procedures notably increase the risk of ureteral damage.1,2,3



Ureteral reconstruction aims to preserve renal function and ensure urinary continuity. This is achieved using similar principles of reconstruction as applied to other organs. These include ensuring good vascular supply, complete excision of pathologic lesions, good drainage, and a wide spatulated and tension-free anastomosis of mucosa to mucosa. The availability of another ureter and the similar transitional epithelial lining of the ureters and bladder allows for various functional options for reconstruction.



Indications and Clinical Applications



1. Iatrogenic ureteric injuries


Iatrogenic injuries occur typically during pelvic surgery and therefore the injury is predominantly to the distal ureter. The best outcomes are obtained when the injury is recognized and dealt with at the time of surgery. Unfortunately, unrecognized injury is common resulting in delayed presentation and diagnosis. Excessive fluid drainage from operatively placed drains, fever, nausea, vomiting, and flank pain due to infection, urinoma, fistula formation, or ureteric obstruction are all worrisome signs of late presentation. A high index of suspicion is necessary to avoid missing the injury. The measurement of creatinine on fluid from drains is a rapid and accurate way of confirming the absence or presence of postoperative urinary leakage.4



From a surgical perspective, the ureter is divided into the abdominal and pelvic portions. The renal pelvis is the upper border of the abdominal ureter and the iliac vessels are the inferior border. The pelvic ureter extends from the iliac vessels to the bladder. A total of 80% of all gynecologic-related ureteral injuries occur below the pelvic brim.



Many ureteral injuries can be repaired endoscopically with a combination of internaureteral stenting and percutaneous nephrostomy tube drainage.5 For the rest, a variety of open and laparoscopic surgical techniques have been utilized, depending on the level of injury.



Evaluation depends mainly on the surgical approach and time of presentation. If the abdomen is open, then mobilization and direct inspection of both ureters in the area of suspected injury is recommended. If direct inspection is not possible, then retrograde pyelography is very sensitive for identifying the injury and will allow stenting if possible. If the presentation is delayed, then an intravenous pyelogram or a computed tomography (CT) urography is recommended to identify the location and number of injuries. Any drain fluid should be sent for analysis for creatinine to confirm the presence of urine.



Operative repair of ureteral injuries requires meticulous techniques and should be performed at the time of the injury when is recognized. Minimizing ureteral trauma and preservation of adequate blood supply are essential steps for a successful outcome. The ureter should be handled gently to avoid ischemia.



The ureter should be mobilized with a generous amount of periureteral tissue to preserve its collateral circulation. The level of ureteral injury dictates the type of surgical repair feasible for a successful outcome. Although a midureteral injury can be repaired with ureteroureterostomy, a distal ureteral injury should not be reconstructed in this fashion, as the distal ureteral stump will be at risk for being devascularized.6



2. Planned oncologic ureteral resections


The same principles of repair apply when an indicated oncological resection of the ureter has to be carried out. In these circumstances a preoperative plan for the repair should be considered in advance. In these cases, patients must be informed preoperatively of the nature of the reconstructive procedure and the potential negative outcomes.



Anatomic Considerations



The ureters, approximately 25 cm long, descend from the renal pelvis to the bladder along the anterior surface of the psoas muscle in the retroperitoneum. In the posterior aspect of the peritoneal cavity, the colonic mesentery rests anteriorly and gonadal vessels lie medial to the ureters. At the pelvic brim, the gonadal vessels cross the ureter at the level of the division of the common iliac vessels. The ureters course over the division of the common iliac vessels from lateral to medial running medial to the internal iliac vessels and turning further medially to enter the posterior wall of the bladder. In the pelvis the ureter passes under the vas deferens in the male, and under the uterine artery in the female (Figures 13-1 and 13-2).




Fig. 13-1.


Retroperitoneal course of the upper ureter. (Reproduced with permission from Luis Chiva.)






Fig. 13-2.


Retroperitoneal course of the lower ureter. (Reproduced with permission from Luis Chiva.)





The blood supply to the ureter comes from the renal artery, gonadal artery, lumbar arteries, and aorta proximally and the internal iliac artery and its branches distally. A delicate network of sub-adventitial vessels supplies the whole course of the ureter (Figure 13-3).




Fig. 13-3.


Vascular network of the ureteric wall distributed from the adventitia. 1. Mucosa. 2. Muscle coat. 3. Adventitia. 4. Mesoureter. 5. Supplying artery and vein. 6. Adventitial vascular plexus. 7. Perforating arteries. 8. Mucosal vascular plexus. (Adapted with permission from Stephan Spitzer, Medical Illustrator.)





The lumen of the ureter is coated with urothelium, an epithelium lying on the lamina propria. This mucous membrane contains a finely entwined mucosal vascular plexus. The muscle layer, responsible for the bilateral alternating peristaltic movements of the ureter, consists primarily of twisted arranged smooth muscle bundles. In cross section, the bundles form 2 muscle layers joined by connective tissue. The inner layer is longitudinal in arrangement, and in the outer layer the muscle bundles are ordered circularly (Figure 13-4). Near the bladder the intrinsic musculature is separated from a third layer, the muscular layer of Waldeyer; it consists of longitudinally arranged muscle bundles, which emerge from the bladder wall into the ureter. The connective tissue of the adventitia, the ureteric cover, contains the adventitial vascular plexus responsible for supplying the ureteral wall. It is divided into an outer and an inner vascular network. The inner network is characterized by a dense complex of vessels, with small perforating arteries running superficially and obliquely through the intrinsic musculature and continuing to the mucosal vascular plexus. The outer network, which is reticulated, contains longitudinal vessels with multiple anastomoses. It is a crucial point that the adventitial vascular network allows the ureter to be extensively mobilized without ischemia if the vascular supply is preserved.7 To illustrate this concept, one can consider how the ureter is completely isolated from its vascular vessels at the time of a conventional renal transplant.




Fig. 13-4.


Anatomic section of the ureter. 1. Mucosa. 2. Muscle coat. 3. Adventitia. 4. Mesoureter. 5. Supplying artery and vein. 6. Adventitial vascular plexus. 7. Perforating arteries. 8. Mucosal vascular plexus. (Adapted with permission from Stephan Spitzer, Medical Illustrator.)





Preoperative Preparation



Box 13-1 KEY SURGICAL INSTRUMENTATION




  • Basic table-fixed retractor



  • Basic laparotomy set



  • Magnification system if needed



  • DeBakey atraumatic vascular tissue forceps



  • Pott scissors



  • Thin vascular needle holders



  • 6-8 F double-J stents



  • Sensor tip guidewire



  • 3-lumen Foley catheter will comfortably fit the ­urethra after calibration



  • 5/0, 3/0, and 2/0 absorbable polidaxone or monofilament sutures



  • Soft suction drain




Any patient being prepared for a surgical resection with suspected involvement of the ureter on CT or magnetic resonance imaging should have a cystoscopy performed. The patient should be informed in detail about the findings and the possible outcomes during and after surgery, including the various options for ureteric stenting, reconstruction, or both. Written informed consent should be obtained that includes the different surgical options available and the specific procedure preferred by the patient, their drawbacks and limitations, and typical complications before and after surgery. We consider bowel preparation a necessity for all patients possibly undergoing ileal or colon surgery in order to reduce the incidence of complications like fistula formation or infection. After 1 day on a low-residue diet, the patient drinks a bowel-cleansing solution until clear stools are obtained. We do not use oral antibiotics, but strongly advocate intravenous antibiotics during and after surgery (gentamicin plus metronidazole) for 3 days.



Surgical Procedures



After assessing the injury or the length of resection, repair should be based on the extent and location of the injury, the patient’s overall status and associated injuries. In the unstable patient, a more conservative approach, such as ureteric ligation and nephrostomy drainage may be most appropriate. Concomitant bowel injuries are not a contraindication to ureteral reconstruction. Endourological techniques, either antegrade or retrograde, may be able to bridge partial or minor defects with a stent.



Most ureteric injuries are short transections and can be repaired with debridement and ureteroureterostomy in the proximal and midureter or with ureteroneocystostomy in the distal ureter. The psoas hitch is a very useful adjunct to creating a tension-free repair in distal ureteric reconstructions.



The principles of ureteral repair are:





  1. Mobilization of the ureter preserving the adventitia.



  2. Debridement of nonviable tissue



  3. Spatulation and a tension-free anastomosis with absorbable sutures



  4. An internal stent and separate retroperitoneal drain.



  5. Omental interposition to separate the repair from associated intra-abdominal injuries or suture lines is recommended.




The different surgical options to achieve these basic principles are outlined in Tables 13-1 and 13-2. More than 1 technique may be used if necessary.




Table 13-1.Surgical procedures to manage upper ureter injuries.




Table 13-2.Surgical procedures to manage lower ureter injuries.



Reconstructive Procedures on the Upper Ureter



1. Ureteroureterostomy


Primary anastomosis of ureteral injuries is feasible when the defect is short. Injuries to the upper and middle ureter are ideal for primary ureteroureterostomy. In cases of necrosis or thermal damage, the ureter should be débrided to viable tissue. As much periureteral tissue as possible should be left attached to the ureter during dissection to preserve ureteral blood supply. Both ends of the divided ureter are spatulated on opposite sides for 1 cm. Spatulation may not be essential in cases where the ureters are dilated. Sutures of 5:0 polydioxanone (PDS) or polyglactin on an avascular atraumatic needle are inserted from the apex of one ureter to the corner of spatulation of the other ureter. A watertight anastomosis of the ureteral wall is then accomplished using either interrupted or running sutures of 5:0. A total of 6 to 8 sutures are usually sufficient. A double-J stent is inserted after completion of one side of the ureteral anastomosis. In cases of concomitant abdominal surgery, the greater omentum can be mobilized and wrapped around the ureteral anastomosis. A surgical drain is elective and is removed postoperatively when drainage disappears. The double-J stent is removed in 4 to 8 weeks (Figure 13-5).




Fig. 13-5.


Spatulation and repair of the defect by ureteroureterostomy.





2. Transureteroureterostomy


There are certain conditions that might exclude the accomplishment of a traditional ureteric reconstruction. For example, extensive resection of a tumor-infiltrated ureter may be necessary in order to maintain curative intent.8 In such cases, techniques such as the psoas hitch or the Boari flap might be impossible due to thickening of the bladder wall, for example, after previous radiation treatment. One can argue that this would be an ideal case for an ileal ureteral replacement; however, prior radiation or concomitant inflammatory bowel disease may make this reconstructive strategy unattractive as well. In these cases, transureteroureterostomy may be contemplated.9 The use of this technique was popularized in the 1960s; however, significant adverse effects have been reported. In subsequent years, there has been a clear reluctance among reconstructive surgeons to perform this technique, which could endanger both renal units (Figure 13-6).




Fig. 13-6.


Final surgical view after transureteroureterostomy. (Adapted with permission from Stephan Spitzer, Medical Illustrator.)





3. Ileal interposition


Since its first description in 1906 by Shoemaker and later popularization by Goodwin et al in the late 1950s, the use of ileal segments for ureteral replacement have become a valued procedure when reconstructing the ureter. Although it was initially described for tuberculosis ureteral obstruction, more recently the indications for its use have broadened. The main advantage of reconstructing the ureter with ileum is the long-term avoidance of nephrostomy tubes, ureteral stents, and nephrectomy.10 Furthermore, the ileal ureter requires no external devices, preserves renal function, and has the advantage of using an uncompromised blood supply in irradiated cases. In cases of total ureteral avulsion or when a long segment is unhealthy or damaged, a segment of ileum can be used to reconstruct the urinary system. Candidates for this operation should have relatively normal kidney function.11 An ileal segment 20 to 25 cm in length is mobilized 15 to 20 cm in length proximal to the ileocecal valve. Bowel continuity is re-established. The isolated ileal segment is then positioned posteriorly in an isoperistaltic fashion. An end-to-end anastomosis between the renal pelvis and the proximal ileal segment is done using running or interrupted 3:0 PDS or polyglactin sutures. If the proximal ureteral segment is healthy, then anastomosis can be performed between the ureter and the ileal segment in an end-side fashion using interrupted 4:0 PDS or polyglactin suture. A double-J stent is inserted in the ureter prior to completion of the anastomosis. Distally the ileal segment is anastomosed to the posterior wall of the bladder. The bladder is mobilized and an anterior cystotomy is done. An end-side ileovesical anastomosis is done on the posterior bladder wall. A circular opening on the posterior bladder wall is removed and the ileum tunneled through the defect. The anastomosis is then done in 2 layers. The inner layer of interrupted or continuous 3:0 reabsorbable sutures inserted through the full thickness of bladder and ileum from within the bladder (through the anterior cystotomy). An outer strengthening layer of interrupted seromuscular sutures is then placed from outside the bladder. The anterior cystotomy is then closed in 1 or 2 layers. Alternatively, the anastomosis between the distal ileal segment and the bladder can be done in the anterior bladder wall. A direct one layer, nontunneled anastomosis with interrupted or continuous 3:0 reabsorbable sutures is placed circumferentially. A large Foley or suprapubic catheter is inserted. Drains are inserted close to all anastomotic sites. The Foley catheter, nephrostomy tube, or both are maintained on dependent drainage for at least 1 week. The bladder catheter may need frequent irrigation. A cystogram is obtained 7 to 10 days postoperatively to ensure there is no extravasation (Figures 13-7 and 13-8).




Fig. 13-7.


Schema showing the ileal interposition. (Adapted with permission from Robert J. Stein, Glickman Urological and Kidney Institute, Cleveland Clinic.)






Fig. 13-8.


Urography showing a left ileal interposition.





4. The Yang–Monti procedure


The feasibility of constructing a long tube from short segments of ileum was first introduced in 1993 by Yang12 and later verified and reproduced by Monti13 in 1997. The basic principle entails isolation of a vascularized segment of ileum 2 to 3 cm in length. An incision on the antimesenteric border will form a rectangular strip. If this strip is folded over its longitudinal axis, then a 6-cm length tube will be created. If more than one ileal ring are joined together, we obtain a tube whose length is 18 cm long (Figure 13-9). A number of authors have reported their experience with remarkable functional outcomes.14 Furthermore, video radiographic studies have demonstrated that the reconfigured tube is capable of active antegrade propulsion of urine from the renal pelvis down to the bladder. This tailoring of the bowel segment has been suggested to improve the functional outcome of this operation by increasing the propulsion of the urine, limiting the absorptive surface area, and decreasing the formation of mucus. More studies are needed to recommend this surgical operation as a standard reconstructive approach in these cases.




Fig. 13-9.


Development of a ileal ureter following the ­Yang-Monti procedure. (Reproduced with permission from Abu Obaidah, MS.)





5. Renal mobilization


In specific circumstances, surgical mobilization of the kidney from its neighboring tissue allows the surgeon to gain up to 3 cm which may allow for a tension-free anastomosis. In these cases, special attention must be paid to avoid torsion of the renal pedicle.



6. Renal autotransplantation


Renal autotransplantation is an alternative to ureteral interposition in cases of complete ureteral avulsion or a long diseased ureteral segment. Renal autotransplantation is best reserved for patients with solitary kidney or compromised renal function.15



Reconstructive Procedures on the Lower Ureter



1. Ureteroneocystostomy


Ureteroneocystostomy is best utilized for injuries involving the distal 3 to 4 cm of the ureter.16 The ureter is mobilized with generous periureteral tissue. The ureter is spatulated and anastomosed to the bladder in an anterior extravesical or intravesical technique. Following the extravesical technique, the bladder musculature is cut, exposing the bladder mucosa over the entire length of the incision. A 1-cm circle of bladder mucosa is removed. The ureter is anastomosed to the bladder using continuous or interrupted 5:0 PDS sutures approximating full thickness of the ureteral wall to the bladder mucosa. A double-J stent is inserted prior to the conclusion of the anastomosis. The bladder muscle is then closed on top of the ureter using interrupted 3:0 absorbable sutures to accomplish an antireflux mechanism. Care should be taken to avoid stricture of the ureter. Otherwise, an intravesical technique can be used. The bladder is opened through an anterior cystotomy. An incision is made on the mucosa in the posterolateral aspect of the bladder. A submucosal tunnel of 2 cm in length is developed. At the end of the tunnel, the bladder wall is perforated and the ureter is taken across the incision under the submucosal tunnel.17

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Jan 12, 2019 | Posted by in GYNECOLOGY | Comments Off on Bladder and Ureteral Substitution and Augmentation
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