0022-5347/95/1532-0308$03.00/0
Vol. 153,308-315,February 1995 Printed in U.S.A.
THE JOURNAL OF UROLOGY Copyright 0 1995 by AMERICANUROLOGICAL ASSOCUTION,
INC.
Original Articles IN SITU TUNNELED BOWEL FLAP TUBES: 2 NEW TECHNIQUES OF A CONTINENT OUTLET FOR MAINZ POUCH CUTANEOUS DIVERSION A. LAMPEL, M. HOHENFELLNER, D. SCHULTZ-LAMPEL AND J. W. T H m O F F From the Department of Urology and Pediatric Urology, Klinikum Barmen, University of Witten IHerdecke Medical School, Wuppertal, Germany
ABSTRACT
In Mainz pouch continent cutaneous urinary diversion, introduction of the in situ tunneled appendix as the continent outlet in 1990 has simplified the surgical technique and greatly increased the acceptance of the procedure. Based on the results of long-term animal studies, 2 new techniques of a continent outlet were randomly used with a Mainz pouch 1 procedure (ileocecal pouch) in 17 patients in whom the appendix was not available or usable for construction of a continent outlet. According to the flap valve principle of the tunneled appendix, in 17 patients a small caliber conduit was created from large bowel wall at the lower pole of the cecum and was tunneled in situ under the mucosa. In technique 1(seromuscular bowel flap tube), a tube lined by serosa was created from a pedicled island flap of large bowel wall in 11 patients. In technique 2 (full thickness bowel flap tube), a tube lined by mucosa was created from a pedicled flap of large bowel wall in 6 patients. After a mean followup of 8 months (range 2 to 17) 16 of 17 patients catheterize the reservoir at intervals of 4 to more than 6 hours using 14 to 16F catheters and are continent day and night without leakage. The only major complication in this series was incontinence in 1patient with a seromuscular bowel flap tube who died of metastatic tumor 6 months postoperatively. KEY WORDS:urinary diversion; urinary reservoirs, continent For continent cutaneous urinary diversion a controllable small caliber conduit we investigated several surgical techThe 2 physiological sphincter system providing continence and al- niques in dogs, which will be reported ~eparately.’~ lowing for voluntary emptying of the reservoir is not yet most promising techniques were then also performed in huavailable. Attempts to use a Scott sphincter on the efferent man cadavers and adapted for use in patients in whom the limb of an intestinal reservoir were associated with a high appendix is not available (previous appendectomy) or usable rate of complications because of erosion of the sphincteric CUR for continent stoma formation (chronic inflammation, impaired blood supply, or strictured, small or short appendix). and incontinence due to atrophy of the compressed bowel.’.’ Based on the surgical technique reported by Per1 in 194g3 Surgical techniques and clinical results of the first 17 patients are presented. and the animal experiments of Basso reported in 1951; Smith and Hinman in 1955 first used an ileal intussusception nipple in the urinary tract for continent ileovesicosPATIENTS AND METHODS torn^.^ In 1978 Kock et a1 reported use of an antiperistaltic ileal intussusception nipple of the efferent limb of an ileal From July 1992 through December 1993, 11women and 6 reservoir as a catheterizable outlet for continent urinary men (mean age 60 years) underwent continent cutaneous diversion.6 Despite large experience with the ileal intussus- urinary diversion with the Mainz pouch 1technique using 2 ception nipples-” and many modifications,”-’6 the tech- new methods to form the continent outlet as described. Indinique still has a long individual learning curve and a rela- cations for urinary diversion were bladder cancer in 12 patively high complication rate.17*l8 tients, incontinence due to a low compliance bladder after Several prerequisites characterize an “ideal” continent radical prostatectomy and removal of a large subtrigond catheterizable outlet for cutaneous urinary diversion, includ- diverticulum in 1,and interstitial cystitis and pelvic pain in ing complete continence without leakage, easy catheteriza- 4. In all patients, the appendix was not available or usable for tion, uncomplicated surgical technique, low complication rate construction of the continence mechanism because of previand universal applicability. The in situ tunneled a p p e n d i ~ , ’ ~ous appendectomy (15 patients) or the intraoperative finding as used since 1990 in the original Mainz pouch 1 tech- of a short (l),strictured or small caliber (less than 14F) niq~e,’~*’~~’’ fulfills most of these requirements. The conti- appendix (1).Alternative techniques of urinary diversion, nence mechanism of the submucosally tunneled appendix is such as ureterosigmoidostomy or the Mainz pouch 2 techbased on the flap valve principle: a small caliber tube is nique (rectosigmoid pouch),’* were not applicable because of compressed in a submucosal tunnel against the muscular diverticulosis of the sigmoid colon in 12 patients, incompewall of the reservoir with increasing filling.’’ tence of the anal sphincter in 4, locally advanced tumor stage Based on the concept of an in situ tunneled, catheterizable in 3 andlor refusal of anal urinary diversion in 4. The 2 new methods of continent outlet construction were Accepted for publication August 1, 1994. randomly assigned using the otherwise standard Mainz pouch
IN SITU TUNNELED BOWEL FLAP TUBES
1 technique. A seromuscular bowel flap tube was used in 11 patients and a full thickness bowel flap tube was used in 6. Followup studies were obtained after 2 to 17 months (mean 81,including imaging of the upper tracts and reservoir (renal ultrasound, excretory urography, radiograph of the pouch and retrograde contrast medium injection into the outlet) and complete urodynamic studies (filling enterocystometry and outlet pressure profiles). With the patient in the supine position, enterocystometry was performed using a double lumen 9F catheter for filling (50 ml. per minute), simultaneously recording the total reservoir pressure with external transducers. Intra-abdominal pressure was measured via an 18F rectal membrane catheter. Corrected reservoir pressure was electronically calculated by subtraction of abdominal pressure from total reservoir pressure. According to the International Continence Society definition of urethral closure pressure, outlet closure pressure of the continence mechanism was calculated by subtraction of reservoir pressure from total outlet pressure.25 The outlet
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pressure profiles were measured with a 7F catheter with 2 micro-tip pressure transducers mounted 5 cm. apart for simultaneous recording of pressures in the reservoir and outlet. Continuous pull-through (1 mm. per second) pressure profiles were obtained with an empty pouch, with the pouch filled to 50% of capacity and with a full pouch. Surgical technique. For formation of the pouch, 10 to 15 cm. of cecum and ascending colon, and 2 ileal loops of the same length each were used in the standardized technique. The continence mechanism was created as step 1 of the procedure before isolation of the bowel segments for pouch formation. This sequence is performed because resection of an additional segment of small bowel would have been required for an ileal intussusception nipple in case of technical difficulties during construction of the new continent outlet. However, it has not yet been necessary intraoperatively to revert to the intussusception nipple technique. Technique 1-seromuscular bowel flap tube: pedicled island flap of large bowel wall. At the lower pole of the cecum, a flap 3 cm. wide and 5 cm. long incorporating the tenia libera 13,14,20p21
FIG. 1. Seromuscular bowel flap tube. A, U-shaped incision (3 X 5 em.) of seromuscular layer at lower pole of cecum and transverse incision of mucosa (0.5 cm.) at oral end of flap for insertion of 18F balloon catheter into lumen of reservoir. B, tubularization of s e r o m d a r bowel flap over 18F balloon catheter. C, suturing of anterior circumference of seromuscular tube to margin of mucosa (inset).
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is outlined with 4 stay sutures. Between the stay sutures a U-shaped incision is made in the seromuscular layer only, leaving the mucosa and the submucosal vessels intact. The U-shaped incision is oriented so that the flap is based distally. The result is a pedicled seromuscular island flap made from the cecum wall (fig. 1, A). At the lateral and medial margins of the longitudinal incisions, 1 to 2 111111. of the seromuscular layer is detached from the underlying mucosa. At the detached end of the flap a 0.5 cm. transverse incision i s made into the mucosa to gain access to the interior of the reservoir (fig. 1, A). An 18F silicone balloon catheter is inserted into the cecum and the peritoneal surface of the seromuscular strip is tubularized over the catheter using 5-Ze1-0 polyglyconate running sutures. The resulting tube has an inner lining of serosa (fig. 1, B).The free end of the tube is sutured to the margin of the incision through the mucosa by 5-zero polyglyconate interrupted sutures (fig. 1, C).As in the Denis Browne technique of urethral reconstruction in hypospadias,26 the seromuscular tube is provided with a muscular buttress by closing the lateral margins of the seromuscular incisions over it, again using 5-zero polyglyconate running sutures. After closure of the outer seromuscular layer, 3 stay sutures are placed at the outlet of the seromuscular tube to facilitate pulling the end through the abdominal wall (fig. 2, A). After the pouch is completed, 2 rows of interrupted sutures are used for fixation of the pouch to the abdominal wall at the outlet: CZerO polyglyconate sutures for intra-abdominal fixation of the pouch to the abdominal wall peritoneum and 3-zero polyglycolic acid sutures for fixation to the external rectus fascia. The anastomosis of the seromuscular outlet to the skin of the umbilicus is accomplished using %zero polyglycolic acid sutures with a sharp needle (fig. 2,B). Technique 2-full thickness bowel flap tube:pedicled flap of large bowel wall. At the lower pole of the cecum, a flap 3 cm. wide and 6 cm. long incorporating the tenia libera is again marked by 4 stay sutures. Between the stay sutures a Ushaped incision through all layers of the bowel wall is oriented so that the resulting bowel flap is based proximally at the confluence of the 3 teniae (fig. 3,A) and 2 stay sutures are
placed in the distal end of the flap. The flap is tubularized over an 18F silicone balloon catheter with 5-zero polyglyconate running sutures, turning the mucosa inward (fig. 3, €3). For submucosal tunneling, a 5 cm. incision of the seromuscular layer only of the tenia omentalis is started at the pedicle of the tube. At the lateral margins of this incision the seromuscular layer is detached from the underlying mucosa to create a space sufficiently wide for submucosal placement of the tube (fig. 3, 0. After the tubularized bowel flap is placed in the submucosal tunnel, the seromuscular layer is closed over it using &Zero polyglyconate running sutures (fig. 4, A). For fuation of the tube to prevent shortening of the tunnel, a few sutures are placed through the serosa of the tube and cecum. At the proximal end of the tunnel, the tube is again fixed to the seromuscularis of the cecum with 3 to 4 sutures of h e r o polyglyconate. The stay sutures at the end of the tube are used to pull the free end of the tube through a small incision in the abdominal wall (fig. 4, B).After the pouch is completed, fixation of the pouch to the peritoneum and external rectus fascia, and anastomosis of the continent outlet to the skin of the umbilicus are identical as described previously. Postoperative management. Ureteral stents are removed after 10 to 12 days but the stomal catheter and a n additional transmural 10F catheter are left indwelling for 6 weeks. The pouch stoma tube is removed after the patient has been taught intermittent self-catheterization to evacuate and inigate the pouch. RESULTS
Patients. The only early complication in this series was a prolonged postoperative recovery phase in a patient who became delirious postoperatively. Followup ranged from 2 to 17 months (mean 8). The 4 patients with interstitial cystitis and pelvic pain remain free of the pelvic symptoms. Eleven of 12 patients with bladder cancer and 1 with prostate cancer have no evidence of disease. One patient with bladder cancer and taking polychemotherapy (methotrexate, vinblastine, epimbicin and cisplatin) after cystectomy died of metastatic
FIG.2. A, embedding seromuscular bowel flap tube in submucosal position. Stay sutures are placed at flat opening of outlet (dashed line shows incision line for detubularization and pouch formation). B , completed Mainz pouch 1 with seromuscular bowel flap tube as closure mechanism. Anastomosis of continent outlet to skin funnel of umbilicus and fixation of pouch to abdominal wall.
IN SITU TUNNELED BOWEL FLAP TUBES
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FIG. 3. Full thickness bowel flap tube. A, U-shaped incision (3 X 6 cm.) of all layers of bowel wall resulting in pedicled bowel flap at lower pole of cecum. B , tubularization of pedicled bowel flap over 18F balloon catheter (dashed line shows incision line of seromuscularis of tenia omentalis starting at pedicle of bowel flap tube). C, tubularized bowel flap. Seromuscular layer of tenia omentalis is incised and detached from underlying mucosa over length of 5 cm. for submucosal embedding of tube.
FIG.4. A, embedding of full thickness bowel flap tube in submucosal tunnel position. B , submucosal tunnel position of full thickness bowel flap tube as closure mechanism (dashed line indicates incision line for detubularization and pouch formation).
disease 6 months postoperatively. At the latest followup, 1 patient had mild and 1 had moderate unilateral upper tract dilatation, and 1 had mild bilateral upper tract dilatation, none of which has required revision to date. The only stoma specific major complication was incontinence in the patient with a seromuscular bowel flap tube who died of progressive tumor 6 months postoperatively. The incontinence was managed with an indwelling Foley catheter. Stoma specific minor complications in 1 patient with a seromuscular bowel flap tube and 1 with a full thickness bowel flap tube consisted of mild stenosis a t the anastomosis of the outlet with the skin of the umbilicus requiring dilation with catheters of increasing size only. Both patients have catheterized the stoma with a 14F tube without problems for more than 6 and 4 months, respectively. Stoma. Catheterization: Of 10 patients with a seromuscular bowel flap tube 4 use 14F and 6 use 16F catheters. All patients use lubricant for catheterization. "he intervals of catheterization vary from 4 to 5 hours (4 patients) and 5 to 6 hours (4) to
more than 6 hours (2). Six patients have full thickness bowel flap tubes: 4 use 14F and 2 use 16F catheters. Three of the 6 patients use lubricant for catheterization. Two patients empty the reservoir after 4 to 5 hours and 4 after 5 to 6 hours. Secretion From the Stoma: Of 10 patients with a seromuscular bowel flap tube 3 use a peanut size pad for protection from a small amount of stomal secretion and 7 use no protection a t all. With the full thickness bowel flap tubes all patients use a small pad for protection from a small amount of mucous secretion from the stomal mucosa. Postoperative Imaging Studies: Radiographs of the pouch did not demonstrate ureteral reflux in any patient. X-rays taken in the lateral projection during retrograde contrast injection into the outlet revealed small caliber conduits of fairly even shape with a mean length of 3 to 4 cm. without morphological differences between both groups (fig. 5). Urodynamic studies. Reservoir: Pouches with seromuscular bowel flap tubes had a mean capacity of 886 ml. (range 680 to 1,200) with a mean total reservoir pressure of 13 cm.
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IN SITU TUNNELED BOWEL FLAP TUBES DISCUSSION
The number of continence mechanisms that have been described for continent urinary diversion suggests that to date a reliable mechanism, which is easy to construct and has a low complication rate, has not yet pouch and Mainz e v ~ l v e d . ~ ~ ' ~ ~ ' ~In~ the ~ ~ Kock ~ pouch techniques, the continence valve is an ileal intussusception nipple that is isoperistaltic in the Mainz pouch with additional fixation to the ileocecal valve with metal staples.33 However, even if the complication rates of an intussuscepted nipple have been lowered t o an acceptable these data clearly demonstrate a long individual learning curve and a rather tedious surgical technique for construction of a lasting intussusception. The submucosally tunneled appendix as used for continence in the Mitrofanoff operation34functions as a flap valve: a small caliber conduit is compressed in a submucosal tunnel against the muscular wall of a reservoir by increasing presFIG.5. Lateral projection of retrograde contrast injection into out- sure as the reservoir is filled." The same principle was let of seromuscular bowel flap tube (arrowheads). applied in 1990 when the in situ tunneled appendix was first used as the continent outlet of a Mainz pouch 1.l' The submucosally embedded appendix has proved to be a reliable water (range 5 to 25) at 50 ml. filling volume and a mean continence mechanism. The surgical technique is straightfortotal reservoir pressure of 23 cm. water (range 10 to 40) with ward and the complication rate is low." Based on the flap valve principle and the concept of an in the pouch filled to maximum capacity. Three of 10 patients had contraction waves during filling, which started at a fill- situ tunneled, catheterizable small caliber conduit, we invesing volume of 200 to 300 ml. (mean 233) and reached a mean tigated several surgical techniques in a dog model for use in total reservoir pressure of 42 cm. water (range 25 to 60). patients in whom the appendix is not available or usable. The There was no leakage during filling in any patient. 2 most promising techniques were adapted for use in humans Pouches with full thickness bowel flap tubes had a mean during construction of the Mainz pouch 1as a seromuscular capacity of 810 ml. (range 600 to 950) with a mean total bowel flap tube35 in 11patients and as a full thickness bowel reservoir pressure of 14 cm. water (range 5 to 20) a t 50 ml. flap tube in 6. filling volume and a mean total reservoir Pressure of 22 cm. Both surgical techniques for the new continent outlet are water (range 15 to 35) with the Pouch filled to maximum easy to learn and perform, and are similar to the technique of capacity. One patient had contraction waves during filling, the in situ tunneled appendix in terms of conception, techniwhich started at a filling volume of 180 ml. and reached a cal difficulty and surgical time needed. If the mucOSa is total reservoir pressure Of 50 Cm. Water. There was no leak- injured during incision ofthe seromuscular layer for submuage during filling in any patient. cosal embedding of the bowel flap tube, it can be closed using Continent Outlet: Outlet pressure profiles were used to 6-zero polyglyconate sutures. Also, with the seromuscular evaluate maximum closure pressures with the Pouch empty, bowel flap intraoperative mossover to the full thickness bowel and filled to 50% and 100% of capacity. The mean maximum technique is possible as long as the transverse incision closure pressures of the seromuscular bowel flap tubes were flap has not been made, which determines the orientation of the 24 cm. water (range to 60) with an empty poUch927 cm. pedicled flap. Crossover from 1 technique to the other was water (range to 60) at 50% capacity and 48 cm' water (range never necessary in our experience t o date. In contrastto an to 80) at 'O0% capacity (fig. '). The mean length Of the appendiceal stoma, with both techniques the caliber of the closure mechanism was 3.4 cm. (range 2.5 to 4.5). The mean maximum closure pressures of the full thickness catheterizable conduit can be determined individually by bowel flap tubes were 30 cm.water (range 15 to 40) with an selecting the appropriate width of the flap. In Our series (mean follOWUp months) Only Of empty pouch, 40 cm.water (range 20 to 50)at 50%capacity and incontinence was encountered, which occurred immediately 55 cm. water (range 30 to at capacity. The mean length of the closure mechanism was 3.8 cm. (range 3.5 to 4,5). after removal of the catheter in a patient with a seromuscular bowel flap tube. The patient had 3 cycles of adjuvant methotrexate, vinblastine, epirubicin and cisplatin polychemotherapy postoperatively because of advanced tumor (stage pT3bpN2M0, grades 3 to 4), during which penod the stoma catheter was left in place, and the patient died of metastatic tumor 6 months postoperatively. Because of the long period with an indwelling catheter and rapid tumor progression, and since autopsy could not be performed, functional and anatomical evaluation of the closure mechanism was not possible. The reason for failure is unknown. All other patients were completely continent day and night without leakage immediately after removal of the stomal catheter with both techniques, and they have remained SO throughout followup. Most patients in both groups empty the reservoirs at intervals of 4 to more than 6 hours, when they experience a sensation of abdominal fullness. Wlth postoperFIG. 6. Outlet profile of seromuscu~ar bowel flap tube ative expansion of the reservoir the intervals between cath(pouch filled to capacity) w t h average closure pressure ( p , , ~of 60 e t ~ r k & m sare increasing but patients are instructed not to an. water. p,,,,. reservoir pressure. pura,outlet pressure exceed an interval of 6 hours. Of our 16 patients 2 do not 19320,2732
,
IN SITU TUNNELED BOWEL FLAP TUBES
awaken during the night for catheterization and they exceed the 6-hour interval a t that time. Comparison of both new techniques of a continent outlet with each other, with the appendiceal stoma and with the intussuscepted nipple reveals a few functional differences. The seromuscular bowel flap tube, which has an inner lining of serosa, offers the advantage that most patients (7 of 10) do not need any protection for secretion from the stoma. In contrast, all patients with a full thickness bowel flap tube, which has a mucosal lining, and the majority with appendiceal stomas and nipples have some mucosal secretion requiring a small protective pad. In contrast, it may be judged as a disadvantage that all patients with a seromuscular bowel flap tube use lubricant for catheterization, while only 50%of the patients with a full thickness bowel flap tube and few patients with an appendiceal stoma or nipple use lubricant for catheterization because of the mucosal lining of the catheterizable conduit. Histological studies of the serosal lining of the seromuscular bowel flap tubes after long-term followup are underway to determine the fate of the serosal surface of the catheterizable conduit. In our animal experiments, followup of 3 months did not reveal any significant changes. There are 2 other types of continence mechanisms in which the serosa comes into contact with urine as reported by B e n c h e k r o ~ n ?and ~ Koff and Wise.30 In the Benchekroun continence mechanism the serosa lines the catheterizable channel.” In 1987 Koff and Wise reported animal experiments in which biopsies were obtained of the serosa of the efferent ileal loop of the continence mechanism, where the serosa is exposed to urine in a bypass channel to the reservoir (“servosphincter”) tailored from ileum.36 Histology initially revealed inflammatory changes and at later followup transformation of the serosa into glandular tissue, resembling a flat layer of bowel mucosa. These experimental findings of overgrowth of the serosa by a flat mucosa were later confirmed in 2 patients by biopsy of the ileal segment within the cuff where the serosa was exposed to urine.30 However, in our technique the serosal lining of the seromuscular bowel flap tube is not permanently exposed to urine as in the technique of Koff and Wise. As expected, filling enterocystometry did not reveal any significant difference to previous urodynamic studies of ileo-
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cecal reservoir^.^^*^^.^^ Outlet pressure profiles of both new closure mechanisms were obtained to determine the maximum outlet closure pressure at different filling volumes (pouch empty, and filled to 50% and 100%of capacity). Pressure profiles revealed a trend towards increasing maximum outlet closure pressures with increasing filling volumes and pressures in the reservoir corroborating the flap valve mechanism with transmission of reservoir pressure to the submucosally embedded conduit. Even though outlet pressure profiles of the full thickness bowel flap tubes were somewhat higher than those of the seromuscular bowel flap tubes, there was no clinical difference in terms of continence or leakage between the 2 techniques or between patients with a high and a low maximum outlet closure pressure. From these results we conclude that only small differences in pressure between outlet and reservoir (defined as outlet closure pressure) are required in our type of flap valve to achieve and maintain continence. This parallels the results of the technique of submucosal ureteral tunneling for ureteral implantation into the bladder or into an intestinal reservoir, which reliably prevents ureteral reflux and generally does not cause upper tract obstruction despite the rather low pressures at which urine is propelled from the upper tracts. The complication rate of the new techniques for a continent outlet was low: 1 case of incontinence (seromuscular bowel flap tube) and 2 cases of mild stoma stenosis requiring dilation only (1 seromuscular bowel flap tube and 1full thickness bowel flap tube). Certainly longer followup will be required to assess the long-term results completely. Ischemic complications of the bowel flaps were not encountered using either technique. The seromuscular bowel flaps can be classified as a combination of pedicled and island flaps, in which most of the submucosal vessels can be easily preserved during preparation of the seromuscular flap. The full thickness bowel flaps are pedicled flaps with a n approximate 2:l ratio of length-&width. We did not encounter any problems in the blood supply of the flaps. The well known risk of stone formation on nipple should not be a problem in the described techniques, since stone formation is usually related to the use of metal staples, which are exposed to urine. In patients, in whom stoma placement in the umbilicus is not desired or possible (for example in bladder exstrophy),
FIG. 7. A, transverse colon ouch for continent urinary diversion with umbilical anastomosis of seromuscular bowel flap tube as closure mechanism. B , sigmoicfcolon pouch for continent urinary diversion with umbilical anastomosis of full thickness bowel flap tube as closure mechanism.
IN SITU TUNNELED BOWEL FLAP TUBES
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the full thickness bowel flap tube technique may be preferable because of the ability to vary the length of the conduit to reach the skin even through a thick abdominal wall. However, the flat configuration of the outlet of the seromuscular bowel flap tube is perfect for anastomosis to the indented skin of the umbilicus. An advantage of both techniques over an ileal intussusception is that 10 to 15 cm. less ileum is needed for construction of the pouch. Preservation of the absorptive surface of ileum has an important role in prevention of the malabsorption syndrome^.^^.^^ A further advantage of both techniques is the universal applicability for continent cutaneous diversion with large bowel segments. In addition to the described cases, we used a seromuscular bowel flap tube as the continent outlet in a transverse colon pouch (fig. 7 , A) and a full thickness bowel flap tube as the continent outlet in a sigmoid colon pouch (fig. 7 , B ) . In conclusion, both new continent outlets seem to meet all of the prerequisites for a continent catheterizable outlet for urinary diversion, including complete continence without leakage, easy catheterization, an uncomplicated surgical technique, a low complication rate and universal applicability. Except for the differences in technical aspects between both types of continent outlet, as well as mucosal secretion and requirements of lubrication for catheterization, comparison of clinical results did not reveal significant differences between the 2 techniques. Further long-term studies will have to determine whether 1 technique will be superior in terms of reliability and durability. In the meantime, we continue to use both techniques more or less randomly instead of nipple valves with the Mainz pouch continent cutaneous urinary diversion. REFERENCES
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