The advent of robotics has increased the use of minimally invasive surgery (MIS) and expanded the possibilities to perform advanced and complex procedures. 

Although the most frequent surgical approach for treatment of distal ureter pathologies is still open surgery, MIS has become an option offering comparable advantages. 

We want to describe our different surgical techniques, depending on the underlying pathology and location of the injury, and present our single-institution outcomes of robot-assisted ureteral reimplantation (RAUR).

With approval from the Ethical Committee we created a retrospective database that included patients who underwent RAUR from 2016 to 2018 due to pathology of benign, oncological, urological and non-urological origin. We excluded pediatric patients, open and conventional laparoscopy approaches. Preoperative clinical assessment included evaluation of symptoms, CT scan and renal function parameters. Patients with vesicoureteral reflux (VUR) underwent a 99mTc-DMSA scan and urethrocystography. Surgery was indicated depending on symptoms, poor or insufficient response after endoscopic treatment, underlying pathology, evidence of obstruction and deterioration of renal function.

Follow-up included evaluation of symptoms and urethrocystography after two weeks, abdominal ultrasound and urinalysis after four weeks and abdominal ultrasound after three and twelve months. Patients with upper-tract TCC underwent cystoscopy and a CT scan at three and six months.

A descriptive statistical analysis of clinical characteristics, intraoperative variables, complications and outcomes of RAUR was performed. 

Surgical technique
The surgical technique depended on the underlying pathology and location of the injury. All the procedures were performed with the Da Vinci Xi robot in a 4 arm configuration. Intravesical reimplantation (IVR) was always associated with psoas hitch for a distal urethral injury. For injuries proximal to the crossing of the iliac vessels IVR and Boari flap were performed. Extravesical ureteral reimplantation (EVR) was performed according to the Lich-Gregoire technique for VUR. 

Patient positioning and trocar placement
The patient is placed in a supine and Trendelenburg position of 10°. Trocar placement is shown in Fig. 1. 

Anatomic landmarks and ureteral dissection 
In case of left ureter RAUR, the sigmoid colon is mobilized to access the retroperitoneal cavity. The common iliac artery and the ureter must be identified. Careful ureteral dissection is a priority in order to preserve its vascularization. Once the stenotic area is located, the ureter is clipped proximally and distally in oncological cases. The ureter is then transected and surgical margins confirmed intra-operatively when applicable. Dissection of the psoas major muscle is then performed. For distal ureter TCC, a bladder cuff is resected and a 3-0 absorbable barbed suture is used for closure. In case of uretero-vaginal fistula (UVF) repair, the ureter is completely dissected and the plane between ureter and vagina is dissected in order to close the vaginal wall in two layers with absorbable sutures. 

Intravesical reimplantation
The anterior wall of the bladder is released preserving the umbilical ligaments. It is mobilized adequately on the contralateral side to achieve a tension free anastomosis.  

For the psoas hitch procedure, the anterior bladder wall is opened using a transverse incision. The ipsilateral most cranial aspect of the bladder is elevated to check if the raised flap easily reaches the intended point of fixation. For fixation of the bladder at the psoas muscle, two to three PDS® 0 sutures are placed through the tendon of the psoas muscle. The sutures must encompass the whole detrusor muscle thickness without mucosa.
 
To obtain a Boari flap, a "U" shaped incision is performed on the anterior bladder wall. The size of the flap has a 2:1 ratio of length to width.  

The ureter is tunneled in the bladder wall with development of an adequate length of submucosal intraluminal ureter as it courses into the bladder. The ureter is then spatulated and the anastomosis is completed with single stitches of Monocryl 4-0. The guidewire and stent are placed through the assistant trocar. Detrusorraphy is performed in one layer with a 3-0 barbed suture. A routine leak test is performed with 150cc of saline solution. 

Extravesical Reimplantation
First, a ureteral stent is placed. The peritoneum is then incised to identify the distal ureter that is isolated and dissected towards the vesico-ureteral junction (VUJ). The ureter is mobilized to achieve sufficient length. A vertical detrusor myotomy is performed to create a lateral tunnel with a 5:1 ratio of length to width recommended by Paquin (1). At this time the bladder is filled to one-third of its capacity with physiologic serum. The detrusor muscle and all muscle fibers are divided down until the mucosa is identified, without perforating it. The ureter is then placed in the newly created tunnel, and the detrusor muscle is reapproximated with a running 3-0 absorbable barbed suture. The peritoneum is closed above the anastomosis.

Overall, 31 patients underwent a RAUR. Most patients were symptomatic (67.7%) and lumbar pain was the most frequent symptom (35.4%).  Twenty-three patients underwent an IVR (74.1%).  IVR with Boari flap and EVR were performed in 4 patients each (12.9%). 

The origin of the ureteral injury was in most cases benign (n=15/48.3%). The most frequent benign finding was fibrosis (n=7/22.5%). Five patients had VUR (16.1%) and 2 patients had ureteral stenosis caused by endometriosis (6,4%). An oncological origin was found in 5 patients (16.1%). The most frequent cause was DU transitional cell carcinoma (9.6%). All iatrogenic ureteral pathologies were secondary to gynecological surgeries (n=11/35.4%).

There were no conversions and no intraoperative complications. The overall complication rate was 29% (n=9), mostly Clavien-Dindo I (pain and hematuria). At median follow-up of 15 months (12-26 months) the median success rate was 90.3%. There were 3 recurrences, all of them after IVR and all due to tumor recurrence of their primary oncological disease (Table 1). If we exclude the oncological cases the success rate at median follow-up was 100%.

In our knowledge this is one of the largest series of RAUR that includes benign and malignant pathology, with a success rate of 90.3%, which is concordant with the results described among the largest series of RAUR (> 90%) (2). 

The advantages offered by the robot for DU stricture disease allows the surgeon to perform fine movements with greater ease. The first RAUR was described by Naeyer in 2007, they concluded that the RA is safe and feasible for the management of DU stricture offering benefits above conventional laparoscopy (3). 

The retrospective nature of the study may limit the veracity of the results. The procedures were performed by 3 different surgeons who have developed their learning curve over the years. This can affect bleeding, median operative time (MOT) and other variables. Referring back to the primary care physician to continue the follow-up of benign lesions might affect the results. It is also unknown if there have not been more recurrences. Long-term outcomes have yet to be established. The heterogeneity of the population is a limitation although the purpose is to describe our experience. Nor have we compared our results with other approaches such as open surgery or laparoscopy.

RAUR for the treatment of mid/distal ureter pathology with benign and oncological origin is feasible, safe and capable of offering excellent short and medium term outcomes. At our institution the RA has completely replaced the open approach in non-urgent procedures. Long-term clinical and radiological follow-up are needed to confirm long-term recurrence rates and functional outcomes.

Paquin AJ. Ureterovesical anastomosis: The description and evaluation of a technique. J Urol. 1959;82:573–83.
Fifer, G. L. et al. Robotic ureteral reconstruction distal to the ureteropelvic junction: a large single institution clinical series with short-term follow up. J. Endourol. 28, 1424–8 (2014).
De Naeyer, G. et al. Pure robot-assisted psoas hitch ureteral reimplantation for distal-ureteral stenosis. J. Endourol. 21, 618–620 (2007).