How small is small enough? Role of robotics in paediatric urology.

The well-known advantages of robotic surgery include improved dexterity, three-dimensional operating view and an improved degree of freedom. Robotic surgery is performed for a wide range of surgeries in urology, which include radical prostatectomy, radical cystectomy, and ureteric reimplantation. Robotic paediatric urology is evolving. The major hindrance in the development of paediatric robotics is, first, the differences in practice patterns in paediatric urology compared with adult urology thereby making development of expertise difficult and secondly it is challenging to conduct proper studies in the paediatric population because of the paucity of cases. The difficulties in conducting these studies include difficulty in designing a proper randomised study, difficulties with blinding, and finally, the ethical issues involved, finally the instruments although in the phase of evolution require a lot of improvement. In this article, we review the relevant articles for paediatric robotic surgery. We emphasise on the technical aspects and results in contemporary paediatric robotic case series.

INTRODUCTION

Robotic assisted surgery is growing by leaps and bounds in pediatric urology. For instance Robot Assisted Laparoscopic Pyeloplasty (RALP) is becoming the procedure of choice in children with pelvi-ureteric junction (PUJ) obstruction. In this article we will attempt to examine in brief the various conditions in which robotic surgery is being applied in pediatric urology. The technical aspects of the procedures will be briefly explained and results of contemporary series examined.

MATERIALS AND METHODS

The articles were reviewed on the PubMed/MEDLINE. The articles reviewed were between January 2007 and 2013. A review of the literature was done using the following key words (‘paediatrics’ [MeSH Terms] OR ‘paediatrics’ [All Fields] OR ‘paediatric’ [All Fields]) AND (‘robotics’ [MeSH Terms] OR ‘robotics [All Fields] OR ‘robotic’ [All Fields]) AND (‘urology’ [MeSH Terms] OR ‘urology’ [All Fields]). The articles were reviewed particularly dealing with training, cost issues, technique and results. In addition, we have also discussed individual procedures, which include pyeloplasty, reimplantation, mitrofanoffs procedure, augmentation cytoplasty.

REVIEW OF LITERATURE

Training

The interest in developing robot-assisted laparoscopy is ever increasing. In a recent study, participants considered training in laparoscopic and robotic surgery among the top three subspecialty they wished to be trained in.[1] This shows the growing interest in robotic pediatric surgery. In another study, the authors assessed the impact of learning the curve on the outcomes in robot-assisted pyeloplasty. They found that, although complications tend to be technical and early in the authors initial experience, operative time decreased with experience and after 15-20 cases it was similar to that of open pyeloplasty with similar outcomes and surgical success.[2] The opinion stands divided regarding the transition of skills set from open surgery to robotic surgery. O’Brien and Shukla alluded to the feasibility of the transition of an open reconstructive surgeon to a robotic surgeon without prior experience of laparoscopy. They confirm the feasibility of the transition of a surgeon form an open surgeon to a robotic surgeon. The number of cases required according to the author was 20.[3]

There has been an ever increasing role of simulation in surgical training and simulation. Currently, the various simulators available for simulation training are the Mimic and the da Vinci simulator. The simulators assess the skill sets in the various tasks performed by the trainee. The feedback is likely to be useful in trainees.

Cost

The major bottleneck in the development of robotic surgery is the capital cost, this holds true for paediatric robotic surgery as well. Rowe et al. used direct internal costs to the institutions to compare the cost of open and robotic surgery in a variety of paediatric urology procedures. They concluded that a short length of hospital stay, prudent and judicious instrument usage, decreasing operating room times, pre-operative patient selection with a competent and consistent robotic team brings down the cost. They opine that although indirect costs may be high the direct costs can be reduced by these measures.[4] Behan et al. concluded that robotic-assisted laparoscopic pyeloplasty in children is associated with human capital gains, for instance, with decreased lost parental wages, and lower hospitalisation expenses. They suggest that future comparative outcome analyses in children should include financial factors such as human capital loss, which can be especially important for families with young children.[5]

INDIVIDUAL PROCEDURES: TECHNICAL CONSIDERATIONS AND RESULTS

Robotic pyeloplasty

Technique

The patient is placed in the kidney position, and the robot docked. Typically three arms are used, and the instruments utilised are a robotic hook, robotic shears. In paediatric age group, the preferred mode of insertion of ports is the open technique. The preplaced stitch helps in securing the fascia and its subsequent closure of the fascia. Although adult robotic instruments can be used, smaller 5 mm paediatric instruments are also available. On the left side, if the pelvis is extrarenal and visible transmesentrically, then a transmesolcolic approach is employed. A retraction stitch is placed through the anterior abdominal wall and thereafter passed through the medial wall helps in orienting the pelvis and performing pyeloplasty [Figure 1]. The da Vinci system with the three-dimensional magnification helps in handling smaller suture material (6-0 or 7-0). Once the anterior layer is sutured the stent is passed antegrade. Owing to the lack of haptic feedback with the robotic system, handling the pelvis and ureter with robotic forceps should be minimized.

Figure 1

Robotic pyeloplasty. (a) The transabdominal stich passed through the abdominal wall and anterior wall of the pelvis. (b) The pelvis incision is marked, the robotic shears and the robotic monopolar hook are useful for this purpose. (c) The dexterity and added degrees of freedom help to pass the angle stich through the “v” of the spatulated ureter. (d) The hitch stich helps to align the ureter with the pelvis and helps in suturing

The debate regarding the placement or non-placement of stents is on-going, a few recent reports suggest that the robotic pyeloplasty can be safely performed without the need for placement of the stent. In a report by Rodriguez et al. they report experience of stentless robotic pyeloplasty in children, they report their experience with this approach in 12 patients with good functional outcome on diuretic renogram at 6 months.[6] In a study by Noh et al. the antegrade stent could be successfully placed in 27 patients, two patients required reterograde stent placement, one patients developed urinary leak.[7] The size of the stent is decided depending on the age and body stature of the patient. In general, the stents are placed by percutaneously placing an angiocathter and the selected stent slides over into the ureter.

RESULTS

Table 1 shows the results of robotic pyeloplasty.

Table 1

Robotic pyeloplasty: Results

Robotic diverticulectomy

The procedure is performed in a Trendlenburg position. The initial port is placed in the umbilicus, and other two ports are placed in the paramedian region. If a bilateral diverticulectomy is to be performed bilateral double J stents are placed in place. The diverticulum can be identified by either a Foley catheter placed in the diverticulum or with a ureteric catheter in place. The procedure starts by identification of the diverticulum and dissection of the bladder. The bladder is closed in layers with an absorbable suture.

Robotic reimplantation

The various approaches described include intravesical and extravesical ureteric reimplantations.

Intravesical ureteric reimplantation

The challenge in intravesical approach (laproscopic or robot assisted) involves maintaining the pneumovesicum and position of the ports intravesically. The advantage of this approach over the conventional laparoscopic approach is uncertain; the most significant advantage is the excellent visualization and improved dexterity. This necessitates the need for continuing work in this approach in the context to its application in complex procedures.[1314]

Extravesical ureteric reimplantation

The camera port is placed in the umbilicus (12 mm) while the two other robotic ports are placed at the midpoint of the line joining the umbilicus to the anterior superior iliac spine. The procedure starts by identifying the ureter and mobilising the ureter for distal 5 cm. A hitch stitch as described by Peters et al. helps in dissecting the posterior surface of the bladder [Figure 2]. The bladder trough for creating the tunnel is created, care is taken not to open the bladder mucosa, if this happens as an extra precaution the bladder catheter is kept for a few extra days and the rent closed with a chromic suture. The exact length of the tunnel to be created is assessed with a marked tape placed in the abdomen. The muscular wall is closed with interrupted 4-0 Vicryl sutures.

Figure 2

Robotic reimplantation. (a) A dilated ureter tapered with a robotic shears. (b) Tapered ureter. (c) Detrussor tunnel created with a robotic hook. (d) Completed detrusorapphy

Initial results with this technique suggest that this technique offers lesser post-operative analgesia shorter hospital stay and equal efficacy.[15]

In a comparative study, authors compare 25 open extravesical reimplantations with 25 intravesical reimplantation. There was no conversion. The mean operating time was longer while the mean hospital stay and pain was less in the robotic group. The success rates defined as no radiologic evidence of reflux was equivalent in both the groups.[16] Similarly in a study by Marchini et al. they compared the outcome in extravesical reimplantation done with an open approach with that of the robotic approach.[17] In an article by Lendvay they describe the tips and tricks, which help in completing a robotic extravesical reimplantation. First, they place percutaneous placed hitch stitches to elevate the bladder and aid in anastomosis and dissection, secondly intermittently throughout the procedure the bladder is intermittently filled or deflated with gas or fluid, this helps in assessing the patency of the bladder mucosa.[18]

Robotic appendicovesicostomy

The important points include assessment of the appendiceal length prior to docking with a peritoneopscopy. The stoma site should be predetermined pre-operatively as a midline detrusotomy requires an umbilical stoma while a lateral detrusotomy requires a right quadrant stoma. If a simultaneous augmentation is performed, the appendicovesicostomy is on the posterior abdominal wall as the augmentation anastomosis is performed later in the procedure. The appendix should be harvested with a cuff of the caecal wall as this tends to prevent stomal stenosis. Once the bladder trough is created the stitch at the distal end of the trough prevents the bladder mucosa from retracting.[19]

Robot-assisted laparoscopic augmentation cystoplasty

This is perhaps the most challenging procedure that can be undertaken by the robotic paediatric urologist. Before tackling, a procedure of this magnitude, a preliminary experience of 100 robotic procedures in children would be mandatory. A 20 cm segment of ileum (15 cm from the ileocecal valve) is selected and isolated. Intestinal continuity is restored by end-to-end anastomosis with a single layer of polyglactin. The bladder is opened in the coronal plane and if an appendicovesicostomy is needed it is implanted in the posterior wall. The isolated segment of ileum is opened on its antimesentric border and anastomosed to the opened out bladder with a running suture of polyglactin. The bladder is drained with a suprapubic tube, a urethral catheter and another catheter through the Mitrofanoff channel. Gundeti et al. pioneered this technique after extensive animal work and published their results in six patients in 2011.[20]

Table 2 results of robot-assisted laparoscopic cystectomy and appendicovesicostomy.

Table 2

Augmentation cystoplasty and appendicovesicostomy: Results

Robot-assisted laparoscopic ureterocalicostomy

An ureterocalicostomy is a procedure in which the ureter is sutured to the lower most calyx of the kidney. This is a salvage operation, which must be in the armamentarium of every urologist operating on the pelvi-ureteric junction. It is reserved for those cases in which scarring at the pyeloureteric junction precludes a redo. The procedure consists in excising a segment of the renal tissue overlying the most dependent lower pole calyx and anastomosing the spatulated ureter to the calyceal mucosa with interrupted sutures. Casale et al. reported a series of nine patients who underwent this procedure and had good drainage at the end of the year.[23]

Robot-assisted laparoscopic ureteroureterostomy and ureterolithotomy

Transperitoneal robotic uretero-ureterostomies have been reported for midureteric strictures and also for the correction of retrocaval ureters.[2425] This can also be applied in the lower ureter in duplex systems where it helps to avoid reimplantation of disparate ureters in the same tunnel. In single or in duplex systems uretero-ureterostomy is helped by the preplacement of a guide wire or a stent. With robotic assistance removal of a large calculus from the ureter at any level with stenting and closure is a relatively simple matter.

Robot-assisted laparoscopic heminephrectomy

The removal of non-functioning moieties of duplex systems by a transperitoneal approach was first reported in 2009 from Boston.[26] In this landmark paper, nine children with a mean age of 7 years underwent partial nephrectomy for non-functioning moieties (four lower and five upper). The technique of partial/hemi nephrectomy involves stenting the ureter to be preserved (for easy indentification during dissection), division of the dilated ureter of the non-functioning moiety and using it as a handle to facilitate subsequent dissection. Non-mobilisation of the pole to be preserved and the careful preservation of the vessels to this pole has been stressed. If a ureteric catheter is placed inside the ureter of the preserved pole injection of methylene blue may help to indentify calyceal leaks. In the series reported all remnant moieties showed good blood flow on Doppler ultrasound, and there was one urinoma, which was aspirated without consequence. If the ureter of the remnant moiety had to be reimplanted or an ectopic ureter had to be followed by deep pelvic dissection the robot was shifted between the legs and redocked. Port positions were altered to suit pelvic surgery. This perhaps is the only problem with using the robotic platform for this procedure.

Ergonomic issues and instrument malfunction

In a study by Chen et al. the incidence of malfunction of the robotic system was analysed. They analysed 14 cases of instrument malfunction. In 10 cases the fault was recoverable while in four cases, it was irrecoverable leading to conversion into laparoscopy in three patients. This emphasises the fact for prior training in laparoscopy.[27]

CONCLUSION

Robotic paediatric procedures are evolving. The available literature and the results are encouraging. The advantages of this approach are quite obvious. Further, large randomised studies are required to compare the operating times and outcomes in comparison to the laparoscopic approach.