Transverse Colonic Conduit
MICHAEL RINK
MARGIT FISCH
J. H. Nelson was the first to describe the high rate of early and late complications using irradiated small intestine for urinary diversion. Subsequently, he described the technique of the transverse colonic conduit in 1969 for the first time (1). Since the first publication, the transverse colonic conduit has been more used with increasing frequency in patients with urologic or gynecologic malignancy who have been treated with radiotherapy (2,3,4,5,6,7). The anatomic origin of the transverse colon in the upper abdomen close to kidneys and renal pelvises distinguishes this bowel segment from the small intestine or other colonic segments elucidating its obvious advantages for certain urinary diversion indications. With its cranial position outside of the pelvic irradiation field, it fulfills the demand to be nonirradiated, which is of utmost importance for a segment to be used for urinary diversion. Nonirradiated bowel segments offer less risk for postoperative urinary leaks and small bowel complications associated with bowel and ureteral anastomoses (3).
Not only the transverse segment but also the ascending and descending colon can be used, which offers an adaptation to the individual patient’s situation. The long mesentery enables individual adaptation with positioning of the stoma either to the left or right upper abdomen. There are no limitations with regard to short ureters. The segment offers the feasibility for nonrefluxing as well as refluxing ureteral implantation (8,9,10). Colonic stomas usually are also less prone to stoma stenosis compared to the ileum.
INDICATIONS
Indications for Surgery
The foremost indication for transverse colonic conduit is urinary diversion in patients with urologic/gynecologic malignancies and irradiation damage of bowel and distal ureters. Further indications comprise urinary incontinence in patients with radiation cystitis, complex vesicovaginal and rectovesicovaginal fistulae after irradiation, recurrent retroperitoneal fibrosis, Crohn disease, and unsuccessful primary urinary diversion requiring conversion. Complex cases of prostate cancer with a history of irradiation or brachytherapy and recurrent stenosis of the posterior urethra and/or fistula formation in addition to a small bladder capacity represent a rare indication. In patients with recurrent urothelial tumors of the ureters, a direct anastomosis of a conduit to the renal pelvises allows direct endoscopic access to the calices.
Contraindications for Surgery
Absolute contraindications for the transverse colonic conduit are irradiation of the upper abdomen, status post extensive colon resection, and ulcerative colitis. In addition, the use of colonic bowel segments should be considered carefully in patients with inflammatory large bowel disease and chronic diarrhea.
DIAGNOSIS
Preoperative Examinations
For upper urinary tract evaluation, an intravenous urography should be performed preoperatively. Nowadays, intravenous urography often is replaced by computerized tomography (CT) with urographic imaging. However, intravenous urography offers the advantage of being diagnostic and functional and may be considered in addition to CT.
Bowel imaging with water-soluble contrast media or colonoscopy should be performed preoperatively to exclude polyps or diverticula.
Patient Preparation
Nowadays, bowel preparation before urinary diversion is debatable, particularly in ileal diversions. For elective colorectal surgery, mechanical bowel preparation has been practiced as a clinical routine for many decades. However, contemporary randomized clinical trials and meta-analyses found no strong evidence supporting the use mechanical bowel preparation for elective colorectal surgery (13). Yet, the authors of this chapter recommend some type of bowel preparation prior to elective colonic surgery to reduce the stool burden. This may facilitate surgery and potentially avoid postoperative complications.
Finding the best localization of the stoma is an integral part of the preoperative preparation and of critical importance regarding avoidance of postoperative difficulties with stoma accessories, thus improving the patients’ quality of life. Marking the site of the stoma should be done in cooperation between urologists and stoma therapists. To achieve best results, the stoma should be placed in an area free of scars or skin folds. The best position is in the epigastric region; the attached stoma plate has to be checked in sitting, lying, and standing positions of the patient. The patient should wear the stoma bag for several hours up to a day prior to surgery to figure out difficulties with the marked and designated location.
Intraoperatively, broad-spectrum antibiotics such as cephalosporins often in combination with metronidazole are usually given.
ALTERNATIVE THERAPY
A continent, cutaneous colon transverse pouch represents an alternative in young and healthy patients capable for catheterization (14).
SURGICAL TECHNIQUE
Instruments required include a basic kidney set with additional instruments for intra-abdominal surgery, an abdominal retractor, suction, and a basin containing prepared iodine solution for disinfection. As suture material, absorbable monofilament sutures such as polyglycolic acid 4-0 are used for closure of the conduit and intestinal anastomosis to reestablish bowel continuity as well as creation of the stoma. The ureters are implanted using 5-0 and 6-0 sutures. Intraoperatively, a gastric tube (alternatively gastrostomy) and a central venous catheter are placed.
Access is gained by median laparotomy. Both ureters are identified as they cross over the iliac vessels and dissected in the cranial direction. The dissection toward the bladder descends until the irradiated level is reached. The ureters are cut above the irradiated field where they show good vascularization. There should be capillary arterial bleeding from the ureteral wall and spontaneous urine efflux. The ureteral stump is ligated, and the cranial end is marked by a stay suture. Depending on the remaining length of the ureters, it is decided which one can be brought to the opposite side by a retromesenteric pull-through. The retromesenteric entrance should be wide enough, and the path of the ureter slightly curved in order not to angle or compress it.
A bowel segment of approximately 15 cm in length in patients with normal weight is selected respecting the course of the vessels (Fig. 76.1). The length of the segment depends on the thickness of abdominal wall. Stay sutures outline the segment. Bowel mobilization differs depending on the segment chosen: If the ascending segment is selected, the right colonic flexure is mobilized. The greater omentum is separated from the transverse colon over a distance of 10 to 15 cm starting at the right side. When the descending colon is chosen, the left colonic flexure has to be mobilized and the left part of the omentum has to be separated from the transverse colon. The selection of a transverse colonic segment makes mobilization of both the right and left flexure necessary as well as a complete separation of the greater omentum from the transverse colon.
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