Urinary Diversions And Neobladders
- Article Author:
- Gregory Chesnut
- Article Author:
- Rebecca Rentea
- Article Editor:
- Stephen Leslie
- Updated:
- 7/25/2020 7:29:24 AM
- For CME on this topic:
- Urinary Diversions And Neobladders CME
- PubMed Link:
- Urinary Diversions And Neobladders
Introduction
The urinary bladder, situated in the extraperitoneal space of the pelvis behind the pubis, is uniquely designed both to provide a low-pressure reservoir for urine storage during the filling phase and to efficiently empty completely during the micturition phase. The layered design of the bladder and its complex neural control allows the normal bladder to fill without involuntary contractions and to empty with a highly coordinated contraction of the detrusor muscled simultaneously with the relaxation of the urinary sphincter(s) to expel urine. Within the urinary system, the bladder is the most common site of malignancy.[1]
For localized muscle-invasive bladder cancers, and in select cases of non-muscle-invasive cancers, removal of the entire bladder with a radical cystectomy and creation of some type of urinary diversion is recommended as the gold standard.[2] In certain other instances, such as refractory chronic bladder pain or where the bladder does not function properly (either due to injury, surgery, or radiation), the bladder can similarly be removed with the creation of urinary diversion. The methods for urinary diversion following cystectomy can be divided into the continent or incontinent diversions. In the continent diversions, urine is stored in a reservoir created by bowel segments prior to voluntarily emptying via volitional voiding or catheterization. In incontinent diversions, urine is diverted into an intestinal segment that is brought to the skin via an ostomy for continuous drainage into a collecting bag.
Anatomy and Physiology
A muscular, extraperitoneal organ in the pelvis, the urinary bladder receives urine from the ureters and drains urine via the urethra. It is anchored at the apex of its dome to the umbilicus via the median umbilical ligament, which is a remnant of the fetal urachus. Immediately to the right and left of the median umbilical ligament, the medial umbilical ligaments, which are the remnants of the obliterated umbilical arteries, also connect the bladder to the umbilicus. The bladder neck connects to the prostate in men and is attached to the pelvic diaphragm via the medial and lateral puboprostatic ligaments in men and the pubovesical ligaments in women.
Arterial blood supply to the bladder arises from the internal iliac arteries. The superior and inferior vesical arteries, with additional inputs from the obturator and inferior gluteal arteries, as well as from the vaginal and uterine arteries in women, merge to form the lateral and posterior bladder pedicles. The venous drainage from the bladder arises from the vesical venous plexus and drains via the internal iliac veins. Lymphatic drainage from the bladder proceeds via the external iliac, internal iliac, obturator, and common iliac lymph node chains.[3] Further spread to the presacral lymph nodes and the retroperitoneal nodes in the paracaval, interaortocaval, and paraaortic lymph node chains can also be seen.[4][5]
The urinary bladder has four distinct layers. The urothelium is the innermost layer and is comprised of the transitional epithelium (urothelium), which is 7-10 cells deep and is composed of apical, intermediate, and basal cells. The apical umbrella cells are in direct contact with the urine and are the first defensive barrier for uropathogenic bacteria while allowing for selective transport of electrolytes across the bladder membrane.[6] Tight junctions and uroplakin proteins render the urothelium impermeable, and these uroplakins have been shown to be primary attachment sites for uropathogenic E coli infections.[7]
The lamina propria layer, deep to the urothelium, contains connective tissue, lymphatics, nerves, and blood vessels. Deep to the lamina propria is the muscularis propria, which contains the smooth muscle, known as the detrusor, which is responsible for bladder contraction. The muscle fascicles are assorted in random directions in the body of the bladder, which is above the trigone, and they are organized in a layered circular configuration at the trigone and bladder neck. These features allow for the bladder to expand to accommodate urine and to empty in a coordinated fashion. The compliance afforded by the bladder's multi-layered design allows for low-pressure filling. Beyond the muscularis are the final layers of the bladder, the serosa, and fat.
Such anatomic features are important in understanding and treating bladder cancer. Once bladder cancer invades into the lamina propria layer, the metastatic potential via lymphatics and blood vessels encountered increases.[8] For cancers that are muscle-invasive, high grade, and recurrent, or which are unresectable using endoscopic techniques, bladder removal by cystectomy is the standard of care. Performing a complete lymph node dissection, according to the lymphatic drainage pattern described above, is an integral component of surgical treatment.[9][10] The lymphatic spread of bladder cancer can be seen in ipsilateral or contralateral pelvic lymph nodes, necessitating a bilateral pelvic lymph node dissection regardless of the location of cancer within the bladder.[11]
When considering urinary tract reconstruction after bladder removal, either continent or incontinent diversion techniques are available. The choice of reconstruction must include patient's desires, abilities, and motivation, as well as medical comorbidities and prior surgical or radiation history, as these factors will determine both the type of reconstruction performed and the choice of bowel segment to be employed in reconstruction. Different segments of bowel have been used in various configurations to create urinary diversions.
The most common segments of bowel used for urinary diversions are the ileum and colon, though the stomach and jejunum have also been utilized less frequently. The use of bowel segments in the urinary diversion can have metabolic consequences. Factors that contribute to metabolic derangements include the choice of bowel segment, the surface area of the bowel segment employed, and the duration of the contact time of the urine in the bowel.[12]
When creating a neobladder or continent cutaneous pouch, the choice of bowel segment and configuration of bowel utilized must allow the reservoir to store urine at low pressure to prevent damage to the upper urinary tract. The reservoir must also maintain the capability to expand to allow for volitional emptying in intervals short enough to avoid excessive metabolic consequences while being able to retain urine for several hours for social continence.[13] Metabolic consequences are less in the ileal conduit, due to a shorter segment of bowel utilized and decreased urine dwell time. Appropriate bowel selection is required to ensure the stoma is appropriately placed to allow for self-care of appliances.[2]
The distal ileum is the most commonly utilized bowel segment for urinary conduits and orthotopic neobladders. The ileum has a relatively small diameter and is quite mobile for optimal positioning in the abdomen or pelvis, based on a reliable blood supply arising from the superior mesenteric artery. The ileum can be opened and folded in such a manner as to allow for a low-pressure reservoir to be constructed as required for a neobladder. There are rare cases in which the ileal mesentery is short or thickened with mesentery so thick that it cannot be folded and brought to a suitable position in the pelvis for an orthotopic neobladder. In such cases, an ileal conduit or a continent cutaneous diversion should be performed. The ileum is rarely involved in radiation fields and, while prior pelvic irradiation has historically served as an indication for a transverse colon conduit, recent studies demonstrate that the ileum can safely be used in the setting of prior pelvic radiation.[14]
Ileum and colon segments can both absorb ammonium, hydrogen, and chloride from urine while excreting bicarbonate.[15] This absorption pattern can result in hyperchloremic metabolic acidosis, with prolonged urine/bowel contact time increasing this risk. The jejunum is rarely used, as its highly porous epithelium allows larger volumes of water to move osmotically into the bowel lumen, which can lead to chronic dehydration. Additionally, the jejunum has chloride-bicarbonate antiports and lacks the sodium-potassium antiports found in the ileum and colon. This can lead to a state of hypochloremic, hyponatremic, hyperkalemic metabolic acidosis, and has been associated with nausea, weakness, and seizures, in addition to dehydration.[16]
Indications
Radical cystectomy with urinary diversion is the most effective treatment for muscle-invasive bladder cancers, with 5-year cancer-specific survival using this treatment reported up to 76%.[17] Most patients are eligible for all urinary reconstructive options. All patients being considered for radical cystectomy should undergo counseling about the varying types of urinary diversion options and must be counseled on the risks and benefits of each one.[18]
Patient-unique and disease-specific factors are important to ensure appropriate diversion is chosen. Patients desiring orthotopic neobladder must be motivated to complete a timed voiding regimen postoperatively and should possess the ability to perform clean intermittent catheterization if needed. These patients should also be advised of the difference in voiding technique with Valsalva voiding. Similarly, patients should understand the potential for daytime or nighttime incontinence after neobladder creation. Patients undergoing an ileal conduit should understand and be capable of caring for their ostomy and appliance. Those considering continent cutaneous urinary diversions must understand that urinary drainage is dependent upon regular, clean intermittent self-catheterization 4 to 6 times each day.
Contraindications
While older age is not a contraindication for neobladder reconstruction, elderly patients should be counseled that there is a higher risk for delayed recovery of urinary control and that they are at higher long term risk for nocturnal incontinence.[19] An ileal conduit technically is a less complicated diversion to perform and can result in shorter operative times with less bowel manipulation when compared to neobladder or continent cutaneous diversions. This technique is associated with decreased short term surgery-related complications and may be more appropriate for older or more frail patients.[12][20]
Patients with cognitive impairment, degenerative neurologic disease, or frailty should be counseled that continent diversions may require dexterity and attention beyond what may be available or possible from family members, caretakers, visiting nurses, or long term care facilities and they may better be served by an ileal conduit.[21]
Approximately 10% of men and up to half of women require intermittent catheterization to adequately empty their neobladders. Therefore, poor manual dexterity, along with an unwillingness to perform or commit to self-catheterization, are contraindications to neobladder creation.[20][22] For the same reason, severe urethral stricture disease is also a contraindication to orthotopic neobladder. Significant preoperative urinary incontinence may signify poor urinary continence with an orthotopic neobladder, and these patients may be better served with an ileal conduit or continent cutaneous diversion.[23]
An orthotopic neobladder is contraindicated in patients with malignancy involving the urethra, either grossly or on intraoperative frozen sectioning. Such patients are at increased risk for urethral recurrence of the disease. Significant disease outside the bladder and plans for adjuvant radiation are also contraindications to neobladder creation.[24] Historically, prior pelvic radiation therapy has been used as an additional contraindication for neobladder creation and usage. Series have shown that, while a neobladder can be safely performed technically in such patients, increased complications and incontinence rates were seen among patients undergoing neobladder formation after prior radiation exposure. These patients would benefit more from an ileal conduit or continent cutaneous urinary diversion.[25]
Similarly, patients with chronic renal or hepatic insufficiency should not undergo orthotopic neobladder surgery. Chronic metabolic acidosis can lead to progressive kidney disease. Many centers use an estimated creatinine clearance of 35-40 ml/min as a minimal requirement for continent diversions.[24] Adequate hepatic function is required to manage reabsorption of ammonium across the bowel mucosa in neobladders. Therefore, hepatic insufficiency is a contraindication for a neobladder as well.[2]
Preparation
Detailed past medical and surgical histories are required to prepare the patient and medical team for urinary diversion surgery. Prior abdominal surgeries and radiation history, with attention to radiation fields, which may include bowel or bladder, are important for surgical decision making. A history of inflammatory bowel disease may limit the use of the colon in diversions. Colonoscopy should be performed prior to using the colon in continent cutaneous urinary diversions to rule out malignancy or evidence of chronic inflammatory bowel disease.[18]
Thorough counseling regarding cystectomy and diversion types is associated with less regret concerning the type of diversion performed and better quality of life postoperatively.[26][27] Multidisciplinary teams involving surgeons, primary care physicians, and enterostomal therapists can help with patient counseling. As many bladder cancer patients undergoing cystectomy have a strong tobacco use history, smoking cessation counseling is also recommended and has been shown to improve perioperative outcomes.[28]
As a preoperative nutritional status, as measured by albumin levels, has been shown to relate to perioperative outcomes following cystectomy with urinary diversion, nutritional consultations preoperatively should be considered.[29][30] Finally, as the median age of bladder cancer diagnosis has been reported to be between 69-73, many older cystectomy patients will need consultations and optimization by their primary care providers, cardiologists, or geriatricians.[31][32]
Patients undergoing small bowel diversions such as ileal conduit or orthotopic neobladder do not, as a matter of routine, undergo bowel preparation. When the colon is used for a conduit or continent cutaneous urinary diversion, many institutions continue to recommend standard mechanical bowel preparation.[33] Preoperative and perioperative use of peripherally acting opioid receptor antagonists has been associated with the earlier return of bowel function and shorter hospital stays.[34] Antibiotic prophylaxis with second or third-generation cephalosporins perioperatively is recommended by the American Urological Association.
Technique
General techniques for ileal conduit, orthotopic neobladder, and continent cutaneous urinary diversions are described below. Open and minimally invasive approaches, either with laparoscopy or robotic assistance, have been described. Principles of adequate exposure and bowel mobilization to allow for tension-free anastomoses are common to each diversion type and surgical approach. Care should be taken to carefully evaluate the blood supply to each segment of bowel used in the urinary reconstruction to assure the diversion is well perfused. In each case, the diversion is started after the bladder, and lymph nodes are removed. The left ureter is passed behind the sigmoid mesentery in preparation for the ureteral anastomosis for each reconstruction.
Ileal Conduit:
An appropriate portion of ileum is selected, which should be approximately 15 cm proximal to the ileocecal valve. The length of the conduit is chosen to allow for appropriate positioning and for tension-free anastomoses of the ureters to the proximal end of the conduit, with approximately 15 cm of ileum generally required for the diversion. The mesenteric blood supply can be visualized by lifting the distal ileum and shining a light through to visualize the avascular plane for the division to ensure adequate blood supply to the conduit.
The distal division is made along the avascular line of Treves, between the ileocecal artery and the terminal branch of the superior mesenteric artery. The mesentery is then divided with a ligature device or with suture ligation. The proximal mesenteric division should be shorter than the distal division, as the distal segment requires greater mobilization to reach the skin. The distal division requires dividing the vascular arcade connecting the terminal branch of the superior mesenteric artery and the ileocolic artery. A gastrointestinal anastomosis (GIA) stapling device is then used to divide the proximal and distal segments of the conduit.
The conduit is then placed into the pelvis, and the ileum to be reconnected to restore bowel continuity is elevated and brought together. A side-to-side anastomosis is completed by excising the antimesenteric corners of the proximal and distal bowel to be reconnected. A gastrointestinal anastomosis stapling device is then used for the anastomosis. The end of the anastomosis is closed with a transverse anastomosis (TA) stapler after the ends are aligned with Allis clamps. The staple line is reinforced, and the mesenteric defect between the anastomosed bowel is realigned with interrupted sutures.
The staple line at the proximal end of the ileal conduit is then excised and closed with running sutures in two layers using the Parker-Kerr technique, and the conduit is aligned to allow for ureteral anastomosis. The ureters are brought to the proximal end of the conduit and are further tapered and spatulated to allow for anastomosis without excessive tension or redundancy of the ureter, which may kink and cause an obstruction. Care must be taken not to handle the ureters directly and risk damaging the blood supply, which is in the adventitial layer. The bowel serosa is grasped and enterotomies made for anastomosis of the ureters, which can be performed with interrupted or running absorbable sutures. Some centers place temporary ureteral stents to help decrease early urinary leak and stricture at anastomotic sites, though the use of stents is not uniformly used, and their role is debated in the literature.[35][36]
The stoma is then brought through the belly of the rectus muscle to be matured to the skin at the pre-selected site. Turnbull loop stomas or rosebud stomas may be created at the surgeon's discretion. After the stoma is matured, the proximal end of the conduit is retroperitonealized by tracking the medial peritoneal flap to the conduit. A stomal catheter is often placed temporarily to ensure adequate drainage of the conduit during the early perioperative period.
After recovery, the patients should be instructed to change their urostomy appliance every 3-4 days and to attach a urinary drainage bag to their ostomy appliance at night to ensure the urine drains away from the conduit, as urine refluxing into the conduit can lead to skin breakdown leading to an increased risk of urinary infection. The appliance does not need to be sterilized, and the conduit does not require irrigation. Simple hydration is effective in promoting adequate urine flow to avoid stasis and infection.
Orthotopic Neobladder:
Numerous orthotopic diversions have been described, each of which relies upon creating a low-pressure reservoir based on double folding of the ileal segment. The distal division, approximately 15 cm proximal to the ileocecal valve, is performed in an identical fashion as described previously for the ileal conduit, though the mesenteric division distally can be deeper to allow for greater mobilization of the bowel segment into the pelvis. Approximately 55 cm of the bowel is measured proximal to this distal division to create the neobladder. Like for the ileal conduit, the bowel to be used for the neobladder is placed into the pelvis while the bowel to be reconnected is anastomosed and the mesenteric trap closed in an identical fashion described previously.
Two 20 cm segments of the ileum are used for the neobladder, and 15 cm of more proximal ileum is used for the afferent limb, which accommodates the ureteral anastomoses. The back wall of the two 20 cm segments is aligned to create a "U" configuration. The bowel is detubularized on the antimesenteric border. The proximal afferent limb is not detubularized. The posterior plate is closed with a running two-layer closure, and the pouch is folded in half in the opposite direction of the posterior plate. The anterior wall is closed, with the distal suture line remaining open for ultimate anastomosis to the urethra.
The ureters are then anastomosed to the afferent limb in an identical fashion as described previously for the ileal conduit. The reservoir is brought to the pelvis, and the urethra-enteric anastomosis is completed with interrupted sutures over a foley catheter. Ureteral stents, if they are used, can be secured to the catheter or externalized. Suprapubic catheter drainage of the neobladder may be used in addition to foley catheter drainage at the surgeon's discretion.
Continent Cutaneous Urinary Diversion:
Though multiple configurations of continent cutaneous urinary diversions have been described, the most performed technique uses a pouch created using the ascending colon and a catheterizable channel created by a portion of the distal ileum. Approximately 30 cm of ascending colon is selected, de-fatted, and divided using a GIA stapler. A 10 cm segment of the terminal ileum is selected as a catheterizable channel. The bowel is divided with continuity restored by anastomosing the terminal ileum to the transverse colon in a side-to-side fashion, as previously described.
The isolated colon segment is detubularized along the anterior tenia. Care is taken to avoid disrupting the ileocecal valve. The catheterizable channel, which will be made using the terminal ileum, is tapered over a 14 Fr catheter using running sutures, and the ileocecal valve is reinforced as the continence mechanism. Sites for ureteroenteric anastomosis are chosen on the posterior wall of the detubularized colon. A small colonic hiatus is created for each ureteral anastomosis, and each ureter is passed from outside-to-inside of the colonic pouch. The ureteral segments are shortened and trimmed as needed to ensure that any redundant or poorly perfused ureter is excised. The ureters are spatulated and anastomosed from inside the pouch with interrupted or running absorbable sutures, and stents can be placed at the surgeon's discretion.
With the ureterocolonic anastomosis complete, the open colon segment is folded and approximated in two layers with absorbable sutures. A cecostomy tube can be placed through the anterior wall of the pouch. The catheterizable channel is then brought to the marked stoma site and matured to the skin using a V-shaped incision with interrupted absorbable sutures. A stoma catheter is then placed and secured.
Complications
Radical cystectomy with urinary diversion is a complex major abdominal operation commonly performed on older patients with cancer and frequently with diabetes, renal and cardiopulmonary comorbidities.[37] As many as two-thirds of patients may experience a complication during the first 90 days after surgery, with up to 20% of these being high grade.[38][39] Over half of surgical complications can be attributed to the urinary diversion, rather than the cystectomy.[38] The most commonly reported complications of cystectomy with a urinary diversion in several series are gastrointestinal, infectious, and urinary.[39][40][41]
Prolonged ileus can be seen in approximately 20% of cases.[42] Risk factors for perioperative venous thromboembolic events include major pelvic surgery, the presence of malignancy, the common use of neoadjuvant chemotherapy, and older age.[43] Such risk is mitigated by the use of prophylactic low molecular weight heparin preoperatively and for 28 days postoperatively.
Ureteroenteric stricture rates between 3% and 17% have been reported, with increasing rates described with longer follow-up.[41][44] Risk factors for stricture include preoperative hydronephrosis, postoperative urine leak, perioperative urinary tract infection, prior abdominal surgery, and history of pelvic radiation. Urine leak from the ureteral anastomosis in the perioperative period can induce chemical peritonitis and contribute to prolonged ileus. Resulting urinomas may become infected and require drainage.
In the longer term, stones have been found to form in 4 to 6% of neobladders and up to 42% of continent cutaneous diversions.[45][46] Parastomal hernias surrounding the ileal conduit have been reported in 5 to 65% of cases, with approximately one third eventually requiring a surgical repair.[24] Chronic acidosis and stasis contribute to the formation of urinary stones in these patients.
Rates of metabolic acidosis vary from 5 to 15% for ileal conduits, 6-13% for orthotopic neobladders, and 26 to 45% for continent cutaneous diversions in recent series.[19][47][48] Chronic acidosis can lead to bone demineralization and osteopenia. Patients with baseline renal insufficiency are at even higher risk.[48][45] SEER analysis showed cystectomy patients have a 21% greater risk of fracture than those without a cystectomy history.[12] Regular evaluation of electrolytes with correction of acidosis and supplemental calcium with Vitamin D supplementation along with either bisphosphonates or RANK ligand inhibitors will likely help prevent this acidosis induced bone demineralization. Periodic DEXA scans are recommended to identify and treat any osteopenia and osteoporosis promptly.
The terminal ileum is the site of vitamin B12 absorption, and patients with diversions that use this intestinal segment are at risk of B12 deficiency. Symptoms of vitamin B12 depletion are non-specific and include lethargy, extreme fatigue, weakness, palpitations, shortness of breath, dizziness, extremely pale skin, neuropathy, visual disturbances, mouth ulcers, and mood changes. The depletion of B12 can take 3 to 4 years to manifest.[16] Annual B12 surveillance and supplementation as needed can prevent sequelae of B12 deficiency.
Clinical Significance
The bladder plays a critical role in storing and releasing urine. When indicated, cystectomy and urinary diversion can effectively treat bladder cancer while maintaining a good quality of life. However, removal of the bladder is a life-changing event even when it cures the underlying problem as intended. Various urinary diversion options are available after cystectomy, and each has unique considerations in the perioperative and postoperative period. Patient-reported quality of life surveys have shown improvement if patients describe their post diversion related goals and participate in informed shared decision making with their medical team preoperatively.[26]
Cystectomy patients are now living longer with their urinary diversions, and longer-term treatment of associated age-related conditions in these patients is important. Physicians treating patients who have undergone cystectomies should be aware of the short and long term consequences of the various urinary diversion types and be prepared to optimize the surveillance and treatment of these individuals.
Enhancing Healthcare Team Outcomes
Cystectomy with urinary diversion is a complex surgery commonly performed in an older and more comorbid patient population. Outcomes have been shown to be improved in centers that perform more operations and have healthcare teams accustomed to the specialized care needed in these patients.[49][50] Optimization of surgical outcomes following cystectomy and urinary diversions begins prior to surgery with preoperative counseling and treatment of underlying disorders. Perioperative management with standardized enhanced recovery clinical pathways (ERAS) can improve outcomes with hospital stays decreased from one week or more to 3 to 4 days.[51]
Common pathway components include narcotic sparing pain management, which often begins preoperatively with epidural anesthesia or regional blocks. Additionally, early enteral feeding, bowel optimization with opioid antagonists, aggressive ambulation, and early involvement of physical therapy, as well as enterostomal therapists, can improve perioperative outcomes. Early mobilization postoperatively with the assistance of physical therapists can also help shorten hospital stays. Occupational therapy for older patients may be important in optimizing each patient’s ability to care for their diversion outside the hospital.
Nursing, Allied Health, and Interprofessional Team Interventions
Many healthcare teams are involved in the care of patients requiring cystectomy with urinary diversion. As part of multidisciplinary care, preoperative and perioperative evaluation and management with nutritionists, anesthesia and pain management teams, geriatricians, smoking cessation counselors, physical and occupational therapists, and primary care teams are vital. Preoperative evaluation of all patients undergoing cystectomy by a dedicated enterostomal therapist is critical, even if an orthotopic neobladder is desired as the primary reconstructive option. The intraoperative evaluation may rarely require conversion to either ileal conduit or continent cutaneous urinary diversion, and preoperative evaluation of the abdomen in varying positions can allow for ideal placement of ileal conduit stoma or catheterizable channel.
Preoperative marking of the stoma site both ensures the surgeon appropriately positions the ostomy and allows for more in-depth preoperative counseling with the patient and his/her family. Preoperative marking has been associated with independent care of ostomy, decreased stoma-related complications, improved appliance application, and earlier resumption of normal activities.[52][53][54] The stoma is most commonly situated in the right lower quadrant of the abdomen. The exact site should be chosen in a position far enough from the midline abdominal incision to allow for postoperative wound healing and within the line-of-sight for the patient. Regular postoperative care by surgical, enterostomal, and primary care teams is required throughout the life of the cystectomy patient.