Robot-assisted complex urinary tract reconstruction using intestinal segments: redefining the paradigm

Complex urinary tract reconstruction has significantly advanced with the increasing use of robot-assisted procedures. Robotic surgery aims to achieve the same outcomes as open surgery while minimizing morbidity by causing less blood loss, faster postoperative recovery, and reducing complications. This article shares our technique, challenges encountered, and experience of robot-assisted complex urinary tract reconstruction using intestinal segments. Between January 2020 to March 2022, 6 patients who underwent robot-assisted complex urinary tract reconstruction using intestinal segments at our centre were retrospectively reviewed. Demographic, clinical, and operative data were recorded. Patients underwent renal function tests, blood gas analysis, and radiographic imaging in the follow-up. Symptomatic and radiologic relief were the criteria for success. Out of 6 cases, three patients underwent ileal ureter replacement, two combined ileal ureter with augmentation ileo-cystoplasty and one augmentation ileo-cystoplasty alone. The mean age, estimated blood loss, length of hospital stay, and follow-up period were 32.6 years, 110 ± 13.1 mL, 7.0 ± 1.1 days, and 11.3 months, respectively. The indications for surgery were either benign ureteral stricture following lithotripsy or sequelae of genitourinary tuberculosis. No intra-operative complications were found. Clavien-Dindo grade-II and Grade-IIIa were found in three and one patient, respectively. During follow-up, none had compromised renal function or acidosis. Robot-assisted complex urinary tract reconstruction using intestinal segments is safe and offers the advantages of minimally invasive techniques. Techniques demonstrated in this article make these reconstructions feasible with good surgical and clinical outcomes.


Introduction
Urologists have routinely used small and large intestinal segments for complex upper and lower urinary tract reconstructive procedures for over five decades, ranging from ileal ureter replacement to augmentation cystoplasty. Urology has always embraced minimally invasive robotic technology for procedures with complex manoeuvrings, such as prostatectomy, cystectomy and pyeloplasty. Now is the time to extend this technology in complex urinary tract reconstruction using intestinal segments. It is feasible to utilise standard open surgical techniques and translate them onto a minimally invasive robotic platform with excellent outcomes and minimal complications.
The management of ureteral stricture takes into consideration the level and length of the defect. Long segment ureteral defects present a challenge to urologists, as it requires a definitive complex reconstructive procedure. Ileal ureter replacement is usually considered the last resort of reconstruction if not amenable by other means such as ureteroureterostomy, Boari's flap or autotransplantation [1]. It was first described by Shoemaker in 1906 for long-segment ureteral defects and was popularised by Goodwin in 1959 [2].
Genitourinary tuberculosis can involve the urinary bladder and characteristically presents with a contracted bladder in advanced stages. Augmentation cystoplasty is performed using an intestinal patch in patients with small-capacity, high-pressure bladders. The performance of the procedure 1 3 is a must for symptomatic relief and to prevent deterioration of the upper tract [3].
These procedures are generally performed through the open approach owing to the inherent complexity associated with the procedure. The standard laparoscopic approach paved the way for robotics due to growing interest in minimally invasive surgery. The use of a robotic platform provides 3D high-definition magnified visualisation, enhanced precision and reach, and a greater degree of freedom for instrument manoeuvrability, thus providing ease in suturing during the complex procedure.
We present our clinical experience with six patients who underwent either ureteral, bladder or combined reconstruction using intestinal segments in our institute. Patient evaluation, pre-operative preparation and modifications such as patient positioning, port placement, docking and undocking, surgical technique, and technical nuances and challenges encountered during the procedure have been described in the article.

Materials and methods
We performed ureteral and bladder reconstruction using intestinal segments in six patients at our institution between January 2020 and March 2022. We retrospectively reviewed the patient's age, gender, clinical history, aetiology, ureteral stricture location and length, bladder capacity, the reconstructive method used, operative data, postoperative complications and clinical outcomes.

Patient evaluation
Based on symptomatology and radiographic imaging, patients are diagnosed with urinary tract obstruction. Contrast-enhanced computed tomography (CT) scans, and cystograms are often used as the initial imaging techniques for patients who exhibit symptoms suggestive of ureteric stricture or small capacity bladder (Fig. 1). For the obstructed unit, a percutaneous nephrostomy tube was inserted prior to surgery. Access to complete simultaneous retrograde and antegrade imaging is made possible through this tube. This may help gauge the overall length of the stricture and approximate stricture location. Pre-anaesthetic medical evaluations should confirm that the patients can be cleared for surgery and that they can endure pneumoperitoneum for an extended time (5-6 h). Robotic-assisted surgery has no size or weight restrictions. In fact, for an obese patient, the robotic approach could be technically simpler than open surgery. The patients were started on clear fluids on the day before the surgery. We usually prescribe 2 L of Peglec oral solution starting the afternoon before the surgery. Oral carbohydrate loading was also done as per enhanced recovery after surgery protocol.

Patient positioning
Surgical positioning depends on the location of the area to be reconstructed. The patient should be positioned first in the dorsal lithotomy position using stirrups or a split leg table (Fig. 2a). We prefer to tuck the arms at the patient's side. It is imperative that the operating table should have Trendelenburg positioning capabilities. After the distal reconstruction, the patient is positioned in a 75° flank position using bolsters for proper cushioning (Fig. 2b). The arm is placed over the head on an arm-board, and an axillary roll is used. Most of these patients have had previous percutaneous nephrostomy tube placement. Preparing the tube in the sterile operative field is beneficial so that it can be manipulated intraoperatively.

Port placement
After performing two ileal ureter replacements in the flankfirst conventional technique, we usually proceed with the bladder-first approach. Pneumoperitoneum is created using the Veress needle technique, which was placed in the infraumbilical fold with the patient in the lithotomy position.
Lithotomy Position Ports. An 8-mm camera port was placed 2 cm above the umbilicus for the patient in the lithotomy position. Two 8-mm robotic ports were placed 15 cm from the pubic symphysis and 8 cm from the midline. A 12-mm assistant port is placed 8 cm inferolateral to the 8-mm robotic port opposite the side to be reconstructed. Another 12-mm assistant port is placed in the suprapubic area 4 cm above the pubic symphysis. The fourth 8-mm robotic port is placed exactly opposite the 12-mm assistant port in the flank region (Fig. 2c).
Flank Position Ports. For the patient in the flank position, the 8-mm camera port was changed to 12-mm assistant port. The 8-mm robotic port on the side intended for reconstruction was used for the camera port. Additional 8-mm robotic ports were positioned in the midclavicular lines, cranial and caudal to the camera port (Fig. 2d). The ports may need to be shifted laterally in the obese patient. All ports should be one fist breadth away to provide optimal robotic arms working space.

Docking
Docking is important and proper positioning of the patient cart is required to prevent undue clashing of robotic arms.

Surgical technique
We usually start with the bladder first approach and place the patient in lithotomy with the Trendelenberg position. The bladder was filled retrogradely with saline, and anterior mobilisation was performed by incising lateral to the obliterated umbilical ligaments to drop it from the abdominal wall. If required, a psoas hitch may be performed to decrease the distance and tension. It is performed with two Vicryl 2-0 sutures in a figure of 8 fashion, with care to avoid entrapping the genitofemoral nerve. For ileal ureter interposition, augmentation ileo-cystoplasty or combined reconstruction, a 25-cm, 20-cm or 35-cm segment of ileum was identified, respectively, with care to preserve the vascularity. The bowel isolation and anastomosis were performed using EndoGIA 60 mm stapling device. For ileal ureter interposition, the cystostomy was performed at the dome (Fig. 3a), where the ureteroneocystostomy is to be performed, and the ileum was oriented in the isoperistaltic configuration. The distal ileovesical anastomosis was performed with V-loc 3-0 suture (Fig. 3b). For augmentation ileo-cystoplasty or combined reconstruction, cystostomy was performed in the coronal plane liberally till the lateral pedicles (Fig. 3d). The 20-cm ileal segment isolated for augmentation was detubularized at the antimesenteric border, folded in a U-shaped manner, and sutured to the native bladder edges with a V-loc 3-0 suture. For combined reconstruction, the distal 10 cm of the isolated 35-cm ileal segment was detubularized alone (Fig. 3e) and sutured to the native bladder edges with a V-loc 3-0 suture (Fig. 3f), and the rest of the 25-cm was used for the ileal ureter. Our usual practice is to place a suprapubic catheter intra-operatively in addition to the urethral catheter in the augmented bladder and fix it with a chromic catgut suture. The strictured or pathologic segment of the ureter need not be excised, as it will lead to unnecessary dissection. Whenever possible, the gonadal vessels should be preserved.
The patient is then repositioned in the flank position for proximal anastomosis in ileal ureter interposition or combined reconstruction. The white line of Toldt was incised, and the colon was reflected medially. The ureter was identified crossing the iliac vessels and was traced superiorly to the renal pelvis. Adequate mobilisation of the renal pelvis is critical in providing a watertight tension-free anastomosis. The healthy pelvi-ureteric junction or proximal ureter was incised circumferentially after adequate mobilisation and spatulated in preparation for wide patent anastomosis ( Fig. 3c). Stay sutures may aid the anastomosis of an intrarenal pelvis or pelvis with surrounding adhesions (Fig. 3h). The proximal pyelo-ileal anastomosis was performed with V-loc 3-0 suture (Fig. 3i).

Ureteral stent placement
A stent serves as the splint following ureteral reconstruction and is typically placed for 21 days, and removal is considered after the absence of urine leak is confirmed. The tableside assistant placed the stent while the patient was in the flank position after the completion of posterior wall anastomosis, and further completion of the anterior wall anastomosis was performed around the stent. We place a 6F 26 cm double-J one-end open ureteral stent over the 0.038 guide wire through the 12-mm assistant port at the appropriate upward angle and, with the assistance of the robotic instruments, guide it into the proximal ureter. With two-point traction by the robotic surgeon, the stent was advanced into the ureter over a guide wire. After the complete length of the ureter was traversed, the wire was removed, and the proximal coil was passed into the renal pelvis before completion of the anastomosis. A Romo Vac closed wound suction unit was placed and brought out through an 8-mm port site after the anastomosis was completed and hemostasis was secured.

Post-operative care
The drain was removed if the output was less than 30 mL for three consecutive days. For ileal ureteric interposition alone, a nephrostogram was performed on postoperative day 21, following which the nephrostomy tube and the catheter were removed if no extravasation was demonstrated. For augmentation ileo-cystoplasty alone, we leave the catheter in place for 21 days and complete cystography. The catheter was removed if the leak was absent. For combined ileal ureter interposition with augmentation ileocystoplasty, nephrostogram and cystography were performed on postoperative day Fig. 3 Surgical technique. a Cystostomy at the dome of the bladder in the ileal ureter alone, b ileo-vesical anastomosis, c transaction and spatulation of proximal ureter for anastomosis, d coronal cystostomy for combined reconstruction, e detubularization of distal ileum for augmentation cystoplasty, f posterior anastomosis of augmentation cystoplasty, g real stricture is sometimes much higher than preopera-tive evaluation (black arrow represents the healthy segment at PUJ level with diseased ureter), h stay sutures for anastomosis aid in the intrarenal pelvis (black arrow marks the opening of the intrarenal pelvis), i proximal pyelo-ileal anastomosis in the intrarenal pelvis (black arrow) 21, and both nephrostomy tube and catheter were removed if the study was satisfactory. Ureteral stents were usually removed six weeks after surgery with a flexible cystoscope under local anaesthesia.

Follow-up
Patients were followed up 1, 3, and 6 months after surgery and at least annually after that. During follow-up, they underwent routine physical examination, blood gas analysis, serum creatinine, and urine routine tests. An intravenous urography is performed four weeks after stent removal to confirm the absence of stenosis in the case of an ileal ureter. Further studies to assess the patency of the ureter and capacity of the bladder (such as intravenous urography, computed tomography urography and cystogram) are performed as needed (Fig. 4). The duration from surgery to the last visit was defined as the total length of follow-up.

Results
A total of six patients, including two females and four males, underwent urinary tract reconstruction using an ileal segment at our institution between 2020 and 2022. The patient demographic, clinical, preoperative, operative and postoperative data are represented in Table 1. The mean age was 32.6 years (range: 22-43). The main indication for urinary tract reconstruction was genitourinary tuberculosis in four patients (66.67%), followed by iatrogenic injuries in two patients (33.33%). Among the six patients, two had pan ureteral strictures with a small capacity bladder, three had multiple ureteric strictures, and one had a small capacity bladder alone. Among them, three received unilateral ileal ureter interposition, two underwent combined ileal ureter replacement with augmentation ileocystoplasty, and one had augmentation ileocystoplasty alone. The surgeries were performed transperitoneal using a four-arm Da Vinci The mean operating time was 370 ± 10 min for ileal ureter alone in the conventional flank-first approach, while it was 285 min in the bladder-first approach. For combined reconstruction and augmentation ileocystoplasty alone, the mean operating time was 380 ± 10 min and 210 min, respectively. The estimated blood loss was 110 ± 13.1 mL. The average return to regular diet was 3 ± 0.8 days, and the mean hospital stay was 7.0 ± 1.1 days. No patient required peri-operative blood transfusion. Concerning postoperative complications, three developed minor grade-2 complications according to the Clavien-Dindo classification within 30 days after surgery. Urinary tract infection was the most common complication in three patients (50.00%). Ileus developed in one patient (16.66%) and resolved with conservative management. One patient developed Clavien-Dindo grade 3a complication (16.66%) due to a urinary leak and was managed by opening clamped nephrostomy tube and placing a pigtail drain in the perinephric space.
The patients have preserved renal function with a creatinine of 0.80 ± 0.18 mg/dL, and GFR of 114.6 ± 15.4, no urinary symptoms, and a mean bladder capacity of 343.3 ± 9.4 mL with insignificant post-void residual at 11.3 months of follow-up, depicted in Table 2. Only one patient who subsequently developed a urinary infection after 30 days of surgery experienced renal deterioration and was treated with antibiotics, after which the serum creatinine came down to normal limits without major complications.

Discussion
The use of intestinal segments in complex urinary tract reconstruction has been described for more than five decades. The ileum is the most preferred segment, owing to its good mobility and rich vasculature, while the colon can also be used. Traditionally, the use of bowel segments in upper and lower urinary tract reconstruction, namely ileal ureter substitution, augmentation cystoplasty and combined ileal ureter and augmentation cystoplasty, has been described with the open technique. Adopting the minimally invasive approach for these reconstructions has been late and slow, mainly because of the complexity of the procedure. Attempts have been made with the laparoscopic approach, but due to difficult manoeuvring, steep learning curve and increased operative time, it has not been widely accepted worldwide. The robotic platform has been welcomed among urologists for its shorter learning curve, improved tissue handling, ease in suturing and allows a minimally invasive approach even in complex reconstruction.
Ileal ureter substitution is a technically demanding reconstruction and was initially described by Goodwin in 1959 as an open procedure [2]. The first pioneering description of laparoscopic three-port ileal ureter replacement was reported in 2000 by Gill et al. [4]. The surgery lasted for eight hours with minimal blood loss and no complications. Since then, only a handful of case reports or series have demonstrated the feasibility and complications associated with the laparoscopic approach [5,6]. There is enormous variability in the number of ports, technique, operative time and hospital stay. Wagner et al. in 2008 reported the first robot-assisted ileal ureter replacement using a transperitoneal 4-port approach [7]. The ileal anastomosis was carried out extracorporeally.
With minimal blood loss and no postoperative complications, the surgery lasted for 540 min. A completely intracorporeal robot-assisted ileal ureter was performed by Brandao et al. in 2014 [8]. Three robotic arms were used with an operative time of 420 min. The longer operative times can be accounted to the patient position change and repeated undocking and docking, deemed necessary for working in upper and lower abdominal compartments. To the best of our knowledge, no more than a dozen cases are reported in the literature, appreciating the use of a robot-assisted, completely intracorporeal technique for ileal ureter replacement. Augmentation cystoplasty was first described almost a century ago in 1889 by Mikulicz. The technique was adopted for the reconstruction of the contracted tuberculous bladder in the 1950s and was popularised worldwide in the 1980s by Bramble [9]. The first laparoscopic bladder augmentation was described by Docimo et al. in 1995 using the stomach [10]. Gill et al. in 2000 reported their outcomes of laparoscopic bladder augmentation with the extracorporeal technique in three patients using the ileum, sigmoid and caecum with the proximal ascending colon [11]. Complete laparoscopic ileocystoplasty was performed in 2002 by Meng et al. and Elliot et al. with a total operative time of 9 h [12,13]. First robot-assisted augmentation cystoplasty using a completely intracorporeal technique was described in a patient suffering from the neurogenic bladder by Al-Othman et al. in 2008.
Ileal ureter replacement and augmentation cystoplasty individually are well-established procedures, but very few reports of combined reconstruction are published in the literature. Wong et al., in 1984, performed combined ileal ureter with cecocystoplasty to treat three patients with urinary tuberculosis [14]. The first description of the completely intracorporeal robot-assisted bilateral ileal ureter and bladder augmentation was given by Zhu and associates in a patient with advanced cervical cancer treated with chemoradiation and surgery [15]. The surgery was completed without intraoperative complications in 360 min with a blood loss of 100 mL.
For the successful completion of complex urinary tract reconstruction, it is imperative to have appropriate imaging preoperatively. CT or MR urogram usually provides sufficient anatomical detail for preoperative surgical planning. A pre-operatively placed PCN tube provides adequate ureteral rest to stabilise the stricture and simultaneous access to complete antegrade and retrograde imaging. This helps estimate the location and exact length of the ureteral defect, thus aids in planning management. The conventional technique of ileal ureter replacement utilises flank position first for ureteral identification and evaluating the exact location and length of the ureteral defect in estimating the length of the ileum to be isolated for reconstruction [8,16]. However, with the advances in imaging modalities, preoperative estimation of the length and location of the ureteral defect correlates well with the intraoperative estimate [17].
In our institution, six patients underwent complex urinary tract reconstruction from January 2020 to March 2022. Among them, a total of five patients underwent ileal ureter substitution, and two of them were combined with augmentation ileocystoplasty. In previous studies, post-ureteroscopic and post-radiation ureteric strictures are the most common indication of the ileal ureter [18]. The use of the abovementioned reconstruction of ureteric strictures as a result of advanced urogenital tuberculosis is reported in very few studies. However, in our study, there are 3 patients with ureteric stricture resulting from GUTB and two patients with iatrogenic ureteric stricture secondary to ureteroscopy who underwent reconstruction. Two patients in whom combined reconstruction was performed were having small contracted bladder in addition to long segment ureteric stricture with advanced urinary tuberculosis. One patient with GUTB had a small capacity contracted bladder and underwent augmentation ileocystoplasty alone. All the patients were managed with PCN preoperatively. The renal function improved or remain unchanged after reconstruction, and none of them required diversion.
In our study, the upper extent of the stricture was found to be higher than the level that was demonstrated in preoperative imaging. As our patients had either long segments or multiple ureteral defects with upper extent as the pelviureteric junction, we intend to isolate a 25-cm long ileal segment for reconstruction in ileal ureteral substitution alone. Out of three patients in whom we performed ileal ureter replacement, the conventional flank-first approach was utilised in two cases early in the learning curve, and the bladder-first approach was utilised in the third case. Bladder-first approach minimizes the prolonged intraoperative time by reducing the patient position change and undocking to just once while maintaining the intraoperative ease of manoeuvring and suturing. Especially, there is great ease in suturing in cases with the intrarenal pelvis, as seen in our two cases.
The length of the ileum used, the reimplantation technique and the voiding pressure all affect the retrograde transmission of intravesical pressure to upper tracts. Some urologists believe that antireflux reimplantation prevents the worsening of renal function, while others assume that the antireflux procedure will impede the urine flow leading to dilatation of the ileal ureter and deterioration of renal 1 3 function. There is no universal agreement about the use of the distal implantation approach and how it affects renal function. However, the natural isoperistaltic waves can stop reflux from reaching the kidney, and an ileal loop longer than 15 cm was thought to be a precaution against the impact of reflux on the kidney, according to several experts. In our study, the ileum was anastomosed to the bladder in a nonrefluxing manner in all cases. On follow-up, however, neither proximal dilatation nor deterioration of renal functions was seen.
The factors which determine the metabolic complications post-procedure are the length of the bowel segment used, preoperative renal function, contact duration of urine with the bowel segment, distal obstruction, stasis, and reflux. It has been found that following the usage of a long and broad diameter ileal segment, metabolic problems such as hyperchloremic metabolic acidosis, renal failure, and hepatic dysfunction are frequently recognised. Hence, keeping the bowel segment length to a minimum will prevent these complications. One of the key factors in the development of these postoperative problems is renal function prior to surgery. Comparable to previous studies, in the present study, no patient was diagnosed to have hyperchloremic acidosis.
Literature suggests that most patients post-procedure experience an improvement or stability of renal function. In a recent and largest retrospective analysis of 157 patients between 1991 and 2016 by Kocot et al., after a follow-up of 54 months, the renal function improved or remained unchanged in 147 (94%) patients [19]. In our study, nadir serum creatinine achieved after insertion of PCN was found in five patients. During follow-up, serum creatinine stabilized in 2 out of 6 patients and in 3 patients further decrease in serum creatinine was seen. Compared to other studies, the findings from our investigation were comparable. Preoperative nephrostomy tubes and optimization prior to final reconstruction are a few possible causes of better stabilization of renal functions postoperatively in our study.
The postoperative risk of UTI, pyelonephritis and metabolic complications from bowel usage in the urinary system must be discussed with patients. Numerous studies have documented successful surgical results, including zero fatality and lower rates of morbidity. In our study, short-term complications such as paralytic ileus and UTI were seen in three patients, but there was no significant morbidity or fatality.
Our centre performed the first completely intracorporeal technique for robotic ileal ureter along with augmentation ileocystoplasty in GUTB on two patients with pan ureteral stricture and small capacity bladder. The large difference in variability in the patient position, number and position of ports, and operative time is commonly attributed to technique and learning curve. Surgical innovation has been sparked by robotic platforms while maintaining patient safety and successful postoperative results. With the delicate tissue manipulation necessary for ureteral repair and the promise of superior cosmesis and less blood loss, robot usage has demonstrated significant benefits. Our findings suggest that it may be possible to reconstruct the urinary tract with ileum without worsening renal functions while minimising postoperative metabolic and bowel-related complications with careful patient selection, preoperative renal function optimization, and prompt postoperative follow-up.
With the surgeon seated in a comfortable position, the robotic platform offers effective ergonomics, 3-D highdefinition vision, articulating wrist that allows for a greater degree of freedom, tremor filtering, and precise manoeuvrability and suturing. The limitation of intracorporeal suturing prevents the widespread use of laparoscopy to treat disorders requiring intricate reconstruction. Contrary to conventional laparoscopic surgery, robotic surgery reduces the learning curve for intracorporeal suturing, and this benefit is significantly more obvious in surgeons with no prior laparoscopic experience. The robot performs effectively for both fine movements in a confined space and larger movements, with a magnified and expansive perspective for accurate dissection. Better magnification is provided, allowing for more accurate isolation and superior reconstruction of the urinary system, reducing the risk of inadvertent harm. The biggest disadvantage is price, although it's possible that the shorter operation time compared to traditional laparoscopy and the greater effectiveness of robots for less skilled surgeons may soon outweigh the higher equipment expenses.

Conclusion
Complex upper and lower urinary tract reconstruction with robotic assistance is feasible and safe. Mid-term data show outstanding results with minimal morbidity, indicating that robotic surgery redefines the challenging paradigm of urinary tract repair employing intestine segments. Early in a surgeon's career, longer operating times should be anticipated. Robotics' application to complex reconstructive urology is a topic of ongoing research. Initial data are promising; however, long-term data will eventually decide how robotics will fit into the arsenal of reconstructive techniques.
Availability of data and material Not applicable.

Conflict of interest
The authors have no relevant financial or non-financial interests to disclose.

Ethics approval
The study was approved by the Institutional Ethical Committee, JIPMER.
Consent to participate Informed consent was obtained from all individual patients included in the study.