Orthotopic Urinary Diversion Using an Ileal Low-Pressure Reservoir With an Afferent Tubular Segment



Orthotopic Urinary Diversion Using an Ileal Low-Pressure Reservoir With an Afferent Tubular Segment


FIONA BURKHARD

URS E. STUDER



An ileal low-pressure orthotopic bladder substitute offers several significant advantages over other forms of orthotopic urinary diversion. One is the ease of surgery, as the operation can be performed by any urologist experienced in performing radical prostatectomy or cystectomy with an ileal conduit (1). The short ileal segment, approximately 55 cm, which is used to construct this bladder substitute, minimizes the risk of intestinal malabsorption. Both the terminal ileum and the ileocecal valve are preserved. The reservoir is constructed as a sphere, thus achieving a maximum volume-to-surface area ratio and maximum capacity from the selected bowel segment (2). Another advantage is the isoperistaltic afferent tubular segment with the end-to-side ureteroileal anastomosis at its proximal end. This allows resection of the distal ureters, including the paraureteral lymphatics, at a safe distance from the cancerous lesion in the bladder and reduces the risk of leaving distal ureters behind that may contain carcinoma in situ. Furthermore, the shorter the remaining ureters are, the better the blood supply at their distal end and the lower the risk of ischemic stricturing of the distal ureter. The peristalsis of the afferent ileal segment acts as a dynamic antireflux mechanism, and in cases of complicated urethral strictures or urethral tumor recurrence, the afferent tubular segment can easily be transformed into an ileal conduit. By slightly modifying this reservoir, it can be applied for bladder augmentation following subtotal cystectomy in patients with benign bladder pathologies.


SELECTION CRITERIA

Patients undergoing orthotopic bladder substitution will generally receive the diversion after cystectomy for bladder cancer. A full workup to stage the cancer is important as well as a cystoscopy to determine the extent of the cancer and exclude involvement of the urethra (negative preoperative biopsies from the prostatic urethra [male]/bladder neck [female]). As is true for all bladder substitutes, specific selection criteria need to be adhered to. In general, metastatic disease should be ruled out. Adequate renal function defined by a glomerular filtration rate >50 mL/min/m2 precludes the need for lifelong bicarbonate supplementation and liver function should be normal (aspartate aminotransferase, alanine aminotransferase). Patients should not have active inflammatory bowel disease or have undergone previous extensive bowel resection (malabsorption). It is important that patients have the mental and physical ability to learn to live with a bladder substitute (comply with voiding intervals, mobility to get to toilet also at night). They also have to be willing to comply with routine follow-up.


INDICATIONS FOR SURGERY

Orthotopic diversion represents the procedure of choice in the properly selected patient undergoing cystectomy. However, as with all bladder substitutes, oncologic outcome and complete resection of the cancer must in no way be compromised by the orthotopic reconstruction. In addition, the external rhabdosphincter and internal lissosphincter complex and their corresponding innervation must remain functionally intact. The ileal orthotopic bladder substitute is particularly well suited for patients in whom the sequelae of ileocecal resection should be avoided.


ALTERNATIVE THERAPIES

Alternatives to the ileal orthotopic bladder include other forms of diversion, including ileal and colon conduits, continent urinary diversions, and other orthotopic diversions.



SURGICAL TECHNIQUE


Cystectomy

Pelvic lymphadenectomy and cystectomy are performed according to standard technique, with slight modifications (3). The external iliac vessels, the obturator fossa, and the hypogastric vessels are completely freed of all lymphatic, fatty, and connective tissue on both the medial and lateral side. After dividing the dorsolateral bladder pedicles, which contain the superior and inferior vesical vessels, close to the hypogastric arteries, the pelvic floor fascia is incised and the Santorini plexus is ligated. The prostatic vessels should be preserved on the non-tumor-bearing side to ensure adequate blood supply to the pelvic plexus and neurovascular bundle.

The ureters are divided where they cross the iliac vessels. This allows en bloc removal of the distal ureters and paraureteral lymphatic vessels, together with the cystectomy specimen. The dorsomedial pedicle is resected along the pararectal-presacral plane on the tumor-bearing side. Whenever possible, care is taken to preserve the hypogastric nerve fibers and the pelvic plexus, which are situated dorsolateral to the seminal vesicles, on the contralateral non-tumor-bearing side. On this side, the dissection along the dorsolateral wall of the seminal vesicles is stopped at the base of the prostate. The neurovascular bundle is then detached from the prostatic capsule in a retrograde fashion. The Santorini plexus is then divided, and the membranous urethra is transected as close as possible to the apex of the prostate by excavating it out of the donut-shaped apex.


Preparation of the Ileum Segment for the Bladder Substitute

For construction of the reservoir, an approximately 55-cm long ileal segment is isolated 25 cm proximal to the ileocecal valve (Fig. 78.1). The length of the ileal segment is measured with a ruler in portions of 10 cm along the border of the mesoileum without stretching the bowel. Irritation of the bowel as well as epidural anesthesia with local anesthetics should be avoided because this can increase smooth muscle tone and activity and thereby “shorten” the bowel, resulting in a measured segment which will be too long after muscle relaxation.






FIGURE 78.1 An approximately 55-cm long ileal segment for the bladder substitute is isolated 25 cm proximal to the ileocecal valve. Note the long incision distally (eases reanastomosis of the ileum and mobilization of the reservoir) and the short incision in the mesoileum proximally (preserves blood supply to the reservoir).

The incision of the mesoileum at the distal or aboral end of the ileal segment is long and transects the communicating vessels between branches of the superior mesenteric artery and the ileocecal artery. In contrast, the proximal incision must be short in order to preserve the main vessels perfusing the future reservoir segment. Bowel continuity is restored with a 4-0 running polyglycolic acid suture incorporating only the seromuscular layer. The mesoileum borders are adapted with a running suture (2-0 polyglycolic acid) in which the mesoileum of the bladder substitute is included (Fig. 78.2). The sutures must be applied superficially, taking care to preserve the blood supply to the bladder substitute. Both ends of the isolated ileal segment are closed by seromuscular running sutures (4-0 polyglycolic acid). The distal end of the ileal segment, approximately 40 to 45 cm long, is opened along its antimesenteric border (see Fig. 78.2), leaving a 10- to 12-cm afferent tubular limb into which the ureters are implanted.


Ureteroileal End-to-Side Anastomosis

The left ureter is mobilized up to the lower pole of the kidney, with care taken to maintain its surrounding blood supply and thereby prevent ischemia. It is then brought without tension to the right side of the abdomen retroperitoneally by crossing the aorta slightly above the inferior mesenteric artery. Note: If the ureters need to be resected close to the kidney (e.g., if there is carcinoma in situ, compromised vascular supply, or previous radiation history), a longer afferent ileal segment can be harvested to bridge the necessary distance. Transpose the opened part of the ileal segment onto the patient’s upper abdominal
wall, with the proximal end of the afferent tubular segment hanging into the abdominal cavity at the level of the common iliac vessels (Fig. 78.3). The ureters are spatulated over a length of 1.5 to 2.0 cm. Incisions (2 cm) are made in the most proximal portion of the afferent tubular ileal segment along the paramedian antimesenteric border. The spatulated ureters are implanted using the Nesbit technique in an open end-to-side fashion using running sutures (Fig. 78.4). To prevent bowel ischemia between the ureteral anastomoses, the right ureter is placed approximately 1 cm distal to the left ureter.






FIGURE 78.2 Bowel continuity is restored with a continuous end-to-end suture incorporating only the seromuscular layer. The incision in the mesoileum is closed; deep sutures are avoided in order not to compromise circulation. Both ends of the isolated ileal segment are closed by seromuscular running sutures. The distal two-thirds of the ileal segment are opened along its antimesenteric border.

Only gold members can continue reading. Log In or Register to continue

Apr 24, 2020 | Posted by in UROLOGY | Comments Off on Orthotopic Urinary Diversion Using an Ileal Low-Pressure Reservoir With an Afferent Tubular Segment
Premium Wordpress Themes by UFO Themes