Ureteroureterostomy (UU) typically refers to an end-to-end anastomosis of the segments of the same ureter, with excision of the intervening injured or scarred ureter. However, in the pediatric population, UU may also be performed in the setting of obstruction of an upper pole ureter associated with a functioning upper pole, whereby the UU is performed in an end-to-side fashion between the upper pole ureter and the lower pole ureter.
The basic concept of transperitoneal ureteroureterostomy (TUU) is to bring the injured ureter from one side across the peritoneal cavity under the mesentery of the intestine to the healthy ureter on the opposite side and to anastomose it. 
Generally, treatment for ureteral injury, stricture, and obstruction depends on the length of the defect, location, etiology, and time of diagnosis. 
Ureteral insults that require UU or TUU result from various conditions, including both blunt and penetrating trauma, iatrogenic injuries, ureteral strictures, and primary and secondary malignancies of pelvic contents.
Less common indications for UU and TUU include a retrocaval ureter or, in pediatrics patients, a functioning but obstructed upper pole moiety of a duplicated collection system (ie, ectopic ureter or ureterocele).
In the setting of renal trauma (blunt, penetrating, or iatrogenic), the interval from injury to recognition is important and should guide management. If the injury is diagnosed within the first 7 days without a significant concomitant infection, surgical exploration and repair may be performed. The presence of an abscess, urinoma, or fistula should delay an attempt at definitive operative repair. If recognition of the ureteral injury is delayed, an initial endourologic approach or nephrostomy drainage may be the most appropriate initial approach, with subsequent open repair deferred for 1-3 months to allow for resolution of infection and inflammation. 
The principles for obtaining successful outcomes for both UU and TUU include prompt diagnosis of the injury in a situation of acute trauma, spatulation of the ureteral end, lack of tension, stenting of the anastomosis, postoperative drainage, and a watertight anastomosis with fine nonreactive absorbable sutures. Although UU is typically performed via an open technique, laparoscopic and robotic approaches have been described. [4, 5, 6]
Regardless of the etiology, UU is the treatment of choice for a short (2-3 cm) ureteral injury involving the upper third of the ureter. Traumatic ureteral injuries occur in the upper ureter in 39% of cases, mid ureter in 31%, and distal ureter in 30%.  In a review of 77 retrospective reviews of ureteral injuries after external trauma, Pereira et al (2010) noted that proximal ureteral injury occurred at a rate of 59.7% (±37), while mid and distal injuries occurred in 25.6% (±30.4) and 20.8% (±24.4) of cases, respectively.  Most traumatic ureteral injuries involve a short-segment loss of ureter; those in the upper and mid ureter can be repaired with mobilization and UU. 
In the setting of an obstructed upper pole moiety (ectopic ureter, ureterocele), an upper pole–to–lower pole UU or ureteropyelostomy may be performed. Upper pole–to–lower pole UU may be performed proximally or distally depending on the surgeon’s preference.
TUU is rarely indicated for traumatic ureteral injuries. However, if more extensive ureteral loss is encountered or when pelvic injuries preclude ureteroneocystostomy (ie, rectal injury, major vascular injury, extensive bladder injury), TUU is an excellent option. 
TUU may also be considered as a treatment option in patients with advanced primary and recurrent pelvic malignancy with unilateral ureteral obstruction, particularly in the setting of prior pelvic irradiation. [2, 10]
TUU is occasionally used in the surgical management of pediatric vesicoureteral reflux. In the setting of a small bladder with bilateral ureteral reflux, bilateral ureteral reimplantation may not be feasible. In this setting, a TUU and single ureteral reimplantation may provide a more successful outcome.
One major contraindication to a TUU is insufficient length of the donor ureter to reach the contralateral ureter in a tension-free manner or a diseased recipient ureter.
Relative contraindications include a history of nephrolithiasis, retroperitoneal fibrosis, urothelial malignancy, chronic pyelonephritis, or abdominopelvic radiation.
If reflux to the recipient ureter is present, it is recommended that it be corrected, unless it is low grade. A limitation of TUU is the difficulty in intubating the donor ureteral orifice postoperatively.
General anesthesia is typically required for open and laparoscopic/robotic ureteroureterostomy (UU) and transperitoneal ureteroureterostomy (TUU).
In patients who are to undergo UU or TUU, stenting of the repair is often advocated. Thus, having the appropriate patient positioning and table setup to allow for intraoperative imaging, either plain film or fluoroscopic, is important to ensure proper stent positioning.
For TUU, the patient is placed in a supine lithotomy position, and the abdomen is opened through a lower midline incision.
UU performed in patients with trauma is often approached via an exploratory laparotomy incision; however, the incision for UU performed for stricture disease varies based on the location of the stricture. For pediatric duplex systems, a proximal upper pole–to–lower pole UU or ureteropyelostomy is often performed through a flank, whereas a distal UU is performed through a Pfannenstiel or Gibson incision.
Deep venous thrombosis prophylaxis should be instituted, particularly in high-risk patients such as those with pelvic malignancies.
A preoperative urine culture should be obtained to ensure that the patient’s urine is sterile at the time of treatment and antibiotic prophylaxis administered prior to incision.
Essential to the outcome of the repair is thorough debridement of all devitalized tissue, meticulous handling of the ureters, and avoidance of skeletonization of the ureters, as well as achieving a tension-free, water-tight anastomosis.
Placement of a drain helps prevent urinoma and possible abscess.
The key components of the ureteroureterostomy (UU) and transperitoneal ureteroureterostomy (TUU) that are common to each technique include the following:
Mobilize the injured ureter carefully, sparing the adventitia widely to prevent devascularization.
Debride the ureter liberally until the edges bleed, especially in patients with high-velocity gunshot wounds.
The ureteral end should be spatulated. Ideally, there should not be a large discrepancy in size between the donor and recipient ureter when performing TUU (see image below).Transureteral ureteroureterostomy.
Repair ureters under magnification with spatulated, tension-free, stented, watertight anastomosis, placing retroperitoneal drains afterward (see image below).Ureteroureterostomy demonstrating the principles of debridement, spatulation, and end-to-end anastomosis.
Consider omental interposition to isolate the repair when possible.
The most appropriate situation for UU as treatment for stricture disease or trauma is a short defect involving the upper ureter or mid ureter. This approach can also be used in a donor ureteral stricture in a renal transplant patient in whom reconstruction by UU to a healthy native ureter is possible and also in a midureteral tumor in the setting of renal insufficiency or a solitary kidney.
The operative approach depends on the level of ureteral disease/damage. A flank approach is suitable for exposure of the upper ureter, a Gibson incision for the mid ureter, and a lower midline incision or use of a prior Pfannenstiel incision for the lower ureter.
The ureter is adherent to the posterior peritoneum and is most easily identified as it crosses the iliac vessels. The diseased/damaged segment is identified and excised completely. Care is taken in mobilizing the ureter to prevent damage to the adventitia.
Once the diseased segment has been excised, the ureteral segments are spatulated for approximately 5-6 mm, 180° apart. The spatulated ureteral ends are anastomosed by first placing a fine absorbable suture through the corner of one ureteral segment and the apex of the other and tying it outside of the lumen. A second suture is placed in the opposite corner and apex and also tied outside the lumen. The anastomosis is completed by running the two sutures and tying them to each other or via interrupted sutures, according to surgeon preference. See the image below.
Prior to completion of the anastomosis, a JJ stent should be placed. If possible, omentum or retroperitoneal fat is mobilized to surround the repair, and a drain is placed in the retroperitoneum near the anastomosis. A Foley catheter is left indwelling.
In the laparoscopic approach to UU, it is ideal to place a ureteral catheter at the outset of the procedure to facilitate ureteral identification and dissection. The remainder of the repair follows guidelines that are similar to those of the open approach.
The use of UU for upper pole–to–lower pole ureteral anastomoses as treatment for obstructed functioning upper pole moieties may be performed via anterior subcostal incision for proximal UU or a Gibson or Pfannenstiel incision for distal UU.
The principles are the same as described for adult UU, but even greater care is taken to minimize manipulation of the ureters, and limited dissection is undertaken to avoid damaging the adventitia.
Placement of a ureteral stent is at the discretion of the surgeon; however, a drain is necessary in all cases.
Prior to starting the procedure, it is helpful if a cystoscopy and guidewire or stent is placed into the recipient ureter. If a guidewire is placed, a stent may be placed at the completion of the procedure over the wire.
The approach is through a lower midline abdominal incision. The peritoneum over the common iliac vessels of the affected side is elevated and opened with scissors, exposing the entire course of the diseased/damaged ureter.
The ureter is transected proximal to the disease/damaged segment, which is excised, and is carefully mobilized by dissecting widely to prevent injury to the adventitia of the ureter. The peritoneum covering the mesentery of the large bowel is opened, and a tunnel is created under the mesentery. The affected ureter is then brought through the tunnel in the mesentery of the large bowel. The peritoneum overlying the common iliac artery on the opposite side is elevated and opened. The healthy recipient ureter is identified and dissected for a short distance to facilitate the anastomosis.
The affected ureter is then brought next to the recipient ureter, and care is taken to ensure that there is mobility and that there will be no tension on the anastomosis. The affected ureter is spatulated, and a 1-cm X 0.5-cm segment of the wall in the recipient ureter is removed for the anastomosis. See image below.
The repair is performed with interrupted 4-0 synthetic absorbable sutures in a through-and-through technique, providing a mucosa-to-mucosa anastomosis. After the anastomosis is completed, the peritoneum is closed over the repair. A drain is placed. The drain is removed when the drainage ceases.
The drain is removed when the drainage ceases.
The ureteral stent is removed approximately one month after the procedure.
Renal ultrasonography is performed approximately 2 months postoperatively and periodically thereafter.
If significant dilatation of the collecting system is found after stent removal, a BUN and creatinine study should be obtained. If dilatation persists or increases, consider further studies to rule out obstruction.
The incidence of complications after the repair of the iatrogenically injured ureter is not reported. However, the complication rate after repair of traumatic ureteral injuries of the ureter is 25%. 
The most common acute complication, occurring in 10%-24% of cases, is prolonged urinary leakage at the anastomotic site, which can present as urinoma, abscess, or peritonitis. Placement of a drain in the retroperitoneum at the time of initial repair allows efficient drainage of leaking urine and early diagnosis of leakage, thus minimizing the risk of such complications. A delay in diagnosis of an anastomotic leak is associated with additional morbidity. 
Other less common complications include stricture and resultant hydronephrosis, abscess, fistula formation, and infection. Long-term complications, usually ureteral stenosis, are less common.
Medications and Medical Devices
No medical substitute for ureteroureterostomy (UU) or transperitoneal ureteroureterostomy (TUU) currently exists. These are both strictly surgical procedures.