Robotic-Assisted Laparoscopic Pyeloplasty

This topic reviews the technique and application of robotic-assisted laparoscopic pyeloplasty (RLP). Open pyeloplasty has been the criterion standard for pyeloplasty, achieving excellent long-term success rates of over 90%, ^[1] despite the disadvantages of longer hospital stay, increased postoperative pain, and slower return to normal activities as compared with laparoscopic renal surgery. ^[2]

Two other forms of surgical options emerged offering minimally invasive techniques. The first was antegrade endopyelotomy through a percutaneous tract. ^{[3, 4]} The second was retrograde endopyelotomy, in which retrograde access is obtained by using fluoroscopy and small-caliber ureteroscopes. ^{[5, 6]} The main attraction of retrograde endopyelotomy is the avoidance of percutaneous access, which allows the procedure to be performed with less morbidity and a shorter inpatient convalescence period or none at all. ^[7]

The first laparoscopic pyeloplasty was reported in 1993. ^{[8, 9]} Many series showed that laparoscopic pyeloplasty was comparable to open pyeloplasty. ^{[10, 11, 12]} Long-term series with a minimum of 2 years’ follow-up reported excellent success rates (96-98%). ^{[13, 4, 14]} Laparoscopic pyeloplasty also achieved good success (eg, 83% in 36 patients) after previous failed procedures (eg, antegrade or retrograde endopyelotomy, balloon dilatation, and open pyeloplasty). ^[15]

Despite the low morbidity of the procedure, the long-term results of endopyelotomy could not be compared with those of open or laparoscopic pyeloplasty. ^[16] The benefit of quick recovery from surgery after endopyelotomy could also be matched by the minimally invasive laparoscopic approach. For these reasons, endopyelotomy gradually took a smaller role in the first-line management of ureteropelvic junction obstruction (UPJO). ^{[17, 18]}

Excellent results notwithstanding, laparoscopic pyeloplasty did not replace open pyeloplasty the way laparoscopic nephrectomy replaced open nephrectomy—mainly because of the steep learning curve required to master advanced laparoscopic skills such as intracorporal suturing, which can be time-consuming and imprecise in the initial learning stages. The development of RLP has reduced the obstacles to learning intracorporeal suturing, which is the main reconstructive step in pyeloplasty. In 2009, RLP surpassed open surgery as the most widely used approach for pyeloplasty in the United States. ^[19]

Most adult patients present with ipsilateral flank pain that was attributed to UPJO. Subsequent imaging with intravenous pyelography (IVP), computed tomography (CT) with excretory phase, and functional radionuclide scanning (eg, mercaptoacetyltriglycine [MAG3] renal scan) typically yields radiographic evidence of obstruction at the ureteropelvic junction (UPJ). Other clinical presentations include worsening renal function, a history of urinary tract infection, and development of stones in the ipsilateral kidney. ^[20]

When patients present with 1 of these clinical scenarios, together with 1 or more radiographic indicators of obstruction at the UPJ, the case can be made for surgical intervention.

Active urinary tract infection should be excluded before surgery. Appropriate antibiotics should be started,* and a negative culture should be obtained preoperatively. Attempts should be made to exclude an upper tract urothelial carcinoma, either radiologically or with a preoperative ureteroscopy, if necessary. If the kidney is nonfunctional, nephrectomy should be considered.

Relative contraindications for RLP include the presence of a long stricture, in which case alternative techniques (eg, ureterocalicostomy or ureteral substitution) should be considered. YV plasty or Fenger plasty may be considered when a crossing vessel is not present and the UPJ anatomy is suitable.

Best practices

Transposition of crossing vessels

Lower-pole crossing vessels, found in 20-50% of patients with UPJO, may compress or distort the UPJ, causing ureteral outflow obstruction (see the image below). ^[21] The causal relationship between UPJO and crossing vessels is not always clear, but some surgical implications certainly exist. Apart from being a source of hemorrhage during endopyelotomy, the presence of crossing vessels can be a negative prognostic factor in endopyelotomy for the treatment of UPJO. ^[22]

In pyeloplasty, crossing vessels may be encountered when the renal pelvis is approached from the upper ureter. Mobilizing these vessels fully and preserving them during dissection is important. Inadvertent ligation of a crossing artery would lead to infarction of the corresponding lower pole parenchyma. In view of these surgical implications, crossing vessels should be identified in the preoperative CT evaluation.

In dismembered pyeloplasty, crossing vessels can be transposed posteriorly before anastomosis is completed. After the ureter is widely mobilized and dismembered, the crossing vessel is transposed posteriorly and its position tested to ensure that the final position is not causing tension on the anastomotic line (see the video below).

Transposition is not required in all situations. Occasionally, adequate mobilization by itself is sufficient to relieve the obstruction, and the anastomosis can be completed with the crossing vessel in its native anterior position relative to the UPJ, with a more cephalad final position (see the video below).

Two studies comparing success rates in patients who had anterior crossing vessels that were transposed with success rates in those who had crossing vessels that were not transposed found no significant differences in radiographic success. ^{[23, 24]} Whether transposition of crossing vessels is indicated should be decided intraoperatively on the basis of the surgeon’s assessment after adequate mobilization (see the video below).

Placement of ureteral stents

Ureteral stents are commonly placed after reconstructive procedures to allow adequate drainage while suture lines heal, thereby avoiding urine leakage in the postoperative period. At the authors’ institution, a ureteral stent is inserted during retrograde pyelography (RVP) just before the surgical procedure. The anastomosis is completed with the preinserted stent in place.

This technique is straightforward and obviates any guide wire manipulation, genitalia access during surgery, flexible cystoscopy, patient repositioning, or C-arm use. In the authors’ view, the stent does not interfere with anastomosis. In fact, with the additional use of a 5-French infant feeding tube, the stent can be used to ensure that the spatulation of the ureter is sufficient to provide a widely patent anastomosis (see the image below).

Many techniques of stent insertion have been described, including the following:

• Cystoscopic-assisted intraoperative stent insertion ^[25]

• Antegrade placement of the stent over a guide wire through the assistant port ^[26]

• Use of a preinserted open-ended ureteral catheter to insert a guide wire in a retrograde manner and exchange it for a ureteral stent ^[27]

With improved anastomotic technique made possible by the dexterity of the robotic arms, watertight closure can be achieved without an indwelling stent in some cases. In one study, of 17 stentless RLPs performed, 2 cases required postoperative stent insertion in the early postoperative period because of increased output from the drain. ^[28] In 1 of the 2, no leakage was demonstrated on RPG during stent placement, suggesting a transient obstruction from a blood clot.

The authors would routinely place a ureteral stent unless previous experience indicates that the patient cannot tolerate a stent, in which case they would counsel the patient on the risks of urine leakage and possible postoperative stent insertion before performing a stentless procedure.

Alternatives to dismembered pyeloplasty

In cases in which the renal pelvis is small with no redundancy, dismembering the ureter may not achieve a tension-free anastomosis. In such cases, YV plasty or Fenger plasty may be considered. In a YV plasty, the 2 limbs of the Y are made along 2 walls of the pelvis, and the long limb is carried down across the UPJ to the upper ureter. The apex of the V flap created is joined to the most caudal end of the ureteric incision (see the video below).

In a Fenger plasty, the UPJ is incised in a longitudinal fashion and then closed transversely (see the video below). If the obstruction is long and the renal pelvis has adequate redundancy, a flap (eg, Culp-Deweerd) can be created from the redundant pelvis to bridge the ureteral gap.

Now that RLP has been found to achieve success rates similar to those of open pyeloplasty while also providing the benefits of minimally invasive surgery, it is fast becoming the operative technique of choice for patients presenting with UPJO.

Single-center comparative series showed RLP to be equivalent to standard laparoscopic pyeloplasty in terms of operating time, complication rate, and success rate. ^{[29, 30, 31]} A meta-analysis of 8 series reported a significantly shorter hospital stay and a nonsignificantly reduced operating time for RLP, as well as similar success rates and complication rates for the 2 techniques. ^[31] The largest multicenter series of LP and RALP in 575 pediatric patients also found shorter hospitalization time and lower postoperative complication rates with RALP (3.2% vs 7.7%). ^[32] A study on 77 patients with symptomatic UPJO found that patients with equivocal diuretic renography were significantly less likely to have subjective resolution of symptoms than patients in the obstructed group. ^[33]  The results from some of the largest reported series of RLP are summarized in the Table below. ^{[34, 35, 36, 37, 38, 39, 40]}

Table. Reported Results of Robotic-Assisted Laparoscopic Pyeloplasty (Open Table in a new window)

In a small retrospective study, Li et al demonstrated that RLP is a safe treatment for severe UPJO in infants younger than 3 months. No serious intraoperative complications occurred, and ultrasonography performed 12 months after the procedure showed that all patients had a significant recovery of renal function. ^[41]