Intestinal interpositioning is generally considered a surgery of last resort in ureteral repair. Surgical alternatives not involving bowel should be explored before using intestine to bridge ureteral defects because of the potential for metabolic derangements that may result. Depending on the location of the ureteral defect, preference should be given to performing ureteroureterostomy, psoas hitch, Boari flap, transureteroureterostomy, or even onlay flaps with appendix or bowel before resorting to ileal interpositioning.
Preoperative antegrade and retrograde ureteral imaging is imperative to delineate the anatomy and defect length. We routinely have a nephrostomy tube placed preoperatively in patients undergoing planned ureteral repair. This aids in performing antegrade ureterography and allows for postoperative drainage. The nephrostomy tube is not removed until ureteral patency has been confirmed postoperatively. Furthermore, adequate renal function of the affected kidney needs to be determined to justify salvage. As a result, patients may require nuclear renogram or differential creatinine clearance if preoperative imaging suggests renal atrophy or impairment. Ideally, patients should have adequate renal function to compensate for potential metabolic derangements that can occur with interposition of intestine into the urinary tract. Use of the Yang-Monti (see later discussion) technique is theoretically advantageous in this regard because of the shorter segment of bowel needed, which may minimize solute reabsorption and metabolic abnormalities.
In select patients, the bladder should be evaluated preoperatively for capacity and function. In patients with large bladders and normal function, a psoas hitch or Boari flap should be performed to help shorten the ureteral defect needed to be bridged by bowel.
Although conflicting data exist in the literature, we do not routinely perform a mechanical bowel prep on patients undergoing intestinal interpositioning. The presence of coexisting gastrointestinal disorders (e.g., Crohn’s disease) should be ascertained to avoid using a segment of diseased bowel to repair to urinary tract.
Incision and Identification of Ureteral Defect
Place the patient in a supine or low lithotomy position with the arms either tucked or at right angles to the table. Consider antegrade or retrograde placement of a guidewire to aid in identification of the diseased ureter. Place a urethral catheter and maintain access to the catheter during the case. Make a midline abdominal incision from the xiphoid process to the pubis to enter the peritoneal cavity. Place body wall retractors to aid visualization.
Divide the lateral attachments of the ascending or descending colon along the white line of Toldt up to and beyond the hepatic or splenic flexure depending on the laterality of ureteral injury. Dissecting the omentum from the transverse colon may aid in further bowel mobilization. Rotate the colon medially to expose the retroperitoneum.
Measure the length of ureter to be replaced using a sterile ruler or umbilical tape. The length of bowel required depends on the size of the ureteral defect. Along with downward mobilization of the kidney, cephalad mobilization of the bladder by ligation of the contralateral vesical pedicle and creation of a psoas hitch or Boari flap will minimize the length of bowel segment needed to reconstruct the ureter. At this time, a decision is made as to which type of ileal interpositioning to perform—intact, isoperistaltic segment versus a Yang-Monti tube. There are no studies in the literature confirming superiority. As a result, the choice is based on surgeon preference and experience. A Yang-Monti tube carries the advantage of requiring a shorter bowel segment (which may minimize metabolic derangements). In addition, the Yang-Monti tube is smaller in diameter and may allow for greater ease of performing a nonrefluxing bladder anastomosis (if desired). However, using an intact, isoperistaltic segment is less technically demanding and may be performed open, laparoscopically or robotically. Furthermore, an intact, isoperistaltic segment allows for bilateral ureteral substitution with the ability to replace the entire lengths of both ureters in the form of a “reverse 7” configuration.
Intact, Isoperistaltic Ileal Segment
Select the desired segment of distal ileum. If possible, avoid the terminal ileum to minimize the risk of vitamin B 12 and bile salt malabsorption. It is generally advisable to overestimate the length of bowel needed and trim the excess. Isolate the segment of bowel as described in the section on ileal conduits ( Fig. 37.1 ). Tag each end of the ileal segment with a long (distal) and short (proximal) stay suture to ensure that placement is isoperistaltic. If possible, close the mesenteric defect with 3-0 silk suture to prevent internal herniation. Irrigate the isolated bowel segment free of enteric contents using copious amounts of saline until the effluent is clear.
For right ureteral replacement, place the ileal segment in the right retroperitoneum by lifting the previously mobilized cecum forward and medial. Adequate mobilization of the ascending colon should prevent the need of passing the ileal segment through the mesentery of the cecum. For left ureteral replacement, create a 5-cm window in the mesentery of the left colon and pass the ileal segment through to the left hemiabdomen. Ensure the mesenteric window is small enough to minimize the risk of internal herniation but large enough to prevent ischemia of the ileal segment. Confirm that the bowel segment is positioned in an isoperistaltic orientation.
End-to-end anastomosis of the proximal ileal segment to the renal pelvis is performed in patients with a dilated, mobile renal pelvis ( Fig. 37.2 ). Spatulate the ureteropelvic junction as needed to correspond to the luminal size of the ileal segment. Alternatively, the antimesenteric border of the proximal ileal segment can be closed with 3-0 absorbable suture until the opening is the same size as the defect in the renal pelvis. If the pelvis is intrarenal or obscured by scar, ileocalycostomy may be advisable. The anastomosis is performed with a single layer of running or interrupted full-thickness 3-0 absorbable sutures. The renal pelvis is filled with saline via the nephrostomy tube to ensure a watertight anastomosis. Additional reinforcing 3-0 absorbable sutures are used as needed. Occasionally, surgical sealants or glues can be used to aid in obtaining a watertight closure.