Robotic-Assisted Laparoscopic Pyeloplasty 

Updated: Nov 12, 2021
Author: Chandru P Sundaram, MD; Chief Editor: Edward David Kim, MD, FACS 



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.

Technical Considerations

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]

Lower-pole crossing vessels causing ureteropelvic Lower-pole crossing vessels causing ureteropelvic junction obstruction.

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).

Robotic-assisted laparoscopic pyeloplasty: posterior transposition.

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).

Robotic-assisted laparoscopic pyeloplasty: without transposition.

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).

Robotic-assisted laparoscopic pyeloplasty: assessment of transposition.

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).

Use of 5-French infant feeding tube and indwelling Use of 5-French infant feeding tube and indwelling stent to assess adequacy of spatulation.

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).

Robotic-assisted laparoscopic pyeloplasty: YV plasty.

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.

Robotic-assisted laparoscopic pyeloplasty: Fenger plasty.


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)

Study (N)

Follow-up (mo)


Operating Time (min)


Hospital Stay (days)

Erdeljan et al 2010 (88)


93% radiographic patency; 93% pain resolution


5 major: migrated stent, urinoma


Etafy et al 2011 (61)


81% radiographic patency and pain resolution


4.9% clogged stent; urine leak


Gupta et al 2010 (85)


96.5% radiographic patency and pain resolution


3 urine leaks; 2 conversions; 1 port-site hernia; 1 volvulus


Mufarrij et al 2008 (140; 3 centers)


95.7% radiographic resolution


7% major (7 were stent migration); 2 urine leaks


Schwentner et al 2007 (92)


96.7% radiographic patency


2 urine leaks; 1 bleeding


Minnillo et al 2011 (155)


96% stable or improved hydronephrosis


7.7% major complications


Lucas et al 2010 (485; multiple centers)


96.7% radiographic patency; 95.4% symptom improvement


5.4% overall; 1.8% urine leak

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]


Periprocedural Care

Patient Education and Consent

After the decision has been made for surgical intervention, the patient should be counseled on all the options available for the treatment of ureteropelvic junction obstruction (UPJO), including endopyelotomy, laparoscopic pyeloplasty, robotic-assisted laparoscopic pyeloplasty (RLP), and open pyeloplasty. The risks and benefits of each procedure should be carefully explained to allow the patient to come to an informed decision.

In the case of RLP, the patient should receive information about the procedure, the possible perioperative complications, and the anticipated postoperative course, as well as about the placement of a ureteral stent and the possible discomfort associated with it. The surgeon should inform the patient of the expected success rate according to his or her own experience. In addition, the surgeon should describe and explain to the patient the secondary procedures that may be considered in the event of persistent obstruction during follow-up.

Preprocedural Evaluation

Radiologic evaluation provides an objective assessment of the degree of obstruction. Each imaging modality provides different anatomic and functional information. Intravenous pyelography (IVP) may be performed in the initial evaluation of flank pain. Findings on IVP include marked hydronephrosis with delayed contrast excretion and a normal-caliber ureter distally.

Computed tomography (CT) provides excellent anatomic information on the kidneys and surrounding structures, the degree of hydronephrosis (see the first image below), and the presence of stones. With contrast enhancement, the presence of lower-pole crossing vessels can be accurately identified (see the second image below).[42] In the delayed excretory phase, filling defects in the renal pelvis should raise suspicion for urothelial malignancies and prompt further ureteroscopic evaluation.

CT scan showing hydronephrosis from ureteropelvic CT scan showing hydronephrosis from ureteropelvic junction obstruction.
Coronal section of CT showing lower-pole crossing Coronal section of CT showing lower-pole crossing vessels.

Functional radionuclide studies, such as mercaptoacetyltriglycine (MAG3) renal scanning, now enable noninvasive measurement of the degree of obstruction and the differential function of the affected kidney. Persistence of radionuclide in the renal pelvis despite a diuretic bolus, with prolonged (>20 minutes) elimination half-time, is diagnostic of obstruction (see the image below).

MAG3 renogram of right ureteropelvic junction obst MAG3 renogram of right ureteropelvic junction obstruction.

In equivocal situations, a Whitaker test may be necessary. This study measures the rise in intrapelvic pressure during infusion of saline through a nephrostomy catheter at a rate of 10 mL/min. An intrapelvic pressure higher than 22 cm water is indicative of obstruction.[43]

Retrograde pyelography (RPG) is useful for appreciating the anatomy and size of the renal pelvis and for determining the exact site and length of obstruction at the ureteropelvic junction (UPJ) relative to the renal pelvis (see the image below). Distal ureteral lesions can also be excluded. RPG can be performed at the same sitting as pyeloplasty, just before the procedure.

Preoperative RPG showing ureteropelvic junction ob Preoperative RPG showing ureteropelvic junction obstruction.

Occasionally, unexpected lesions (eg, polyps or small filling defects in the renal pelvis) may be demonstrated on RPG that could not be seen on CT scan (see the images below). If a suspicious urothelial lesion is seen, further ureteroscopic evaluation is warranted.

RPG demonstrating polyps at ureteropelvic junction RPG demonstrating polyps at ureteropelvic junction.
Intraoperative view of ureteropelvic junction poly Intraoperative view of ureteropelvic junction polyps causing ureteropelvic junction obstruction.

After RPG is done, a ureteral stent may be inserted up the affected ureter. An open-ended ureteric catheter is used to measure the length of the ureter from the UPJ to the ureteric orifice. The length of the stent chosen should be about 4 cm longer than the measured length of the ureter; this helps prevent the distal end from migrating into the ureter during intraoperative manipulation.


RLP is performed with the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA). Instruments used in RLP include the following:

  • Right arm – Monopolar da Vinci Hot Shears, da Vinci Potts Scissors, da Vinci Large Needle Driver

  • Left arm – da Vinci PK (Plasma Kinetic; Gyrus ACMI, Southborough, MA) Dissecting Forceps, da Vinci Fine Tissue Forceps, da Vinci Large Needle Driver

  • Fourth arm – The authors typically do not use the fourth arm for pyeloplasty but rely on retraction sutures and stay sutures to restrict the number of trocars to 4 on the left and 5 on the right (an additional 5-mm trocar is used for retraction of the liver)

  • Assistant – Stryker Flow 2 suction irrigator (Stryker, Kalamazoo, MI)

Sutures used in RLP include the following:

  • Anastomotic suture – 4-0 or 5-0 polyglactin on RB-1 needle, cut to 5 in.

  • Retraction suture – 2-0 polyglactin

Patient Preparation

A negative preoperative urine culture should be obtained, and any urine infection should be treated appropriately. On the day before surgery, the patient is advised to take light meals, and the bowel is cleared with a laxative. From midnight onward, the patient fasts.


After completion of RVP during the same general anesthesia, the patient is moved so that the umbilicus is placed at the break of the table. The patient is then turned to a modified flank position at a 45° angle. The authors use an inflatable beanbag and blanket rolls placed behind the back to support the patient in this position. An axillary roll is placed just below the dependent axilla. The table is flexed slightly to increase the space over the ipsilateral flank.

The contralateral arm is placed on an arm board perpendicular to the table, and the ipsilateral arm is placed at the side of the body along the midaxillary line; placing the ipsilateral arm at the side instead of on an Allen armrest avoids collision with the upper robotic arm. The upper leg is extended, and the lower leg is flexed at the hip and knee, with a pillow placed between the legs for support. Bony prominences at the hip, knees and ankles are padded. The patient is secured to the table with tape at the chest, hips, and knees (see the image below).

Patient position before draping. Patient position before draping.

The table is rolled to either side before draping to ensure that the patient’s position is secure, especially the position of the head. Finally, the position of the table is adjusted relative to the operating room to allow the patient side cart to be brought to the patient’s upper back or shoulder (see the image below).

Patient cart position. Patient cart position.

Monitoring and Follow-up

On postoperative day 1, the patient is allowed to resume a regular diet and is asked to ambulate. If drainage output is not excessive, the urethral catheter is removed, and the patient is allowed to void. Fluid from the bulb drain is measured for creatinine. If the creatinine level is normal, the drain is removed, and the patient can be discharged on postoperative day 1 or 2.

After 4-6 weeks, the patient returns for removal of the stent; 6-8 weeks after stent removal, a MAG3 renogram is obtained to evaluate for patency and resolution of obstruction. Further renograms are obtained 6 months and 18 months postoperatively.



Laparoscopic Pyeloplasty With Robotic Assistance

Port placement

With the patient rotated to almost a supine position, pneumoperitoneum is created via a Veress needle placed at the umbilicus. After insufflation to a pressure of 15 mm Hg, a 12-mm bladeless trocar is inserted at the umbilicus. A regular 10-mm laparoscope is inserted, and the abdominal cavity is inspected for injury and adhesions. On the right side, a 5-mm subxiphisternal port is inserted to allow retraction of the liver.

The table is now rolled toward the surgeon so that the patient is at a 90° angle relative to horizontal. Additional trocars are placed according to 1 of the following 3 configurations:

  • Lateral laparoscope position

  • Modified paramedian position

  • Medial position

Lateral laparoscope position

The lateral laparoscope position (also referred to as the diamond pattern) is used for robotic-assisted laparoscopic pyeloplasty (RLP) in pediatric patients and smaller adults. A 12-mm port for the robotic camera is situated 2 cm medial and inferior to the tip of the 12th rib, approximately along the anterior axillary line. At this position, the robotic camera is placed with the lens facing upward at a 30° angle.

Next, a pair of 8-mm robotic trocars are placed. The first is placed 2 cm inferior to the costal margin, just medial to the midclavicular line, and the other is placed 2 fingerbreadths superior to the iliac crest, just lateral to the midclavicular line. If the fourth robotic arm is used, the third 8-mm trocar can be placed medial and inferior to the lower robotic port, almost at the suprapubic region (see the images below). After the patient cart is docked, the 12-mm umbilical port is used for the assistant’s instruments.

Diagram of port placement with robotic laparoscope Diagram of port placement with robotic laparoscope placed laterally.
Intraoperative view of port placement. Intraoperative view of port placement.

Modified paramedian position

In most adults, the laparoscope can be moved medially toward the lateral border of the rectus abdominis or the midclavicular line about 3 cm above the level of the umbilicus. The 8-mm trocar for the right-hand robotic instrument is inserted in the subcostal location in line with the laparoscope. The 8-mm trocar for the left-hand robotic instrument is inserted between the umbilicus and the anterior superior iliac spine.

Medial position

The robotic camera can also be placed through the umbilical port. When the camera is inserted in this medially located position, it should be oriented so that the lens faces downward at a 30° angle.

Mobilization of ureteropelvic junction

The first step in exposing the ureteropelvic junction (UPJ) is to reflect the colon by incising the line of Toldt. The plane between the colon and mesocolon and Gerota’s fascia is developed as the colon is reflected medially. In thin patients with minimal mesenteric fat, left-side exposure can be achieved via the transmesocolic approach.[44]

The next landmark is the gonadal vein, which can be identified at the level of the lower pole of the kidney after adequate medial mobilization of the colon. Posterior to the gonadal vein, the psoas fascia can be seen. In this region, the ureter can usually be identified. At this point, the Foley catheter is clamped to allow urine to flow back up the stent and distend the renal pelvis.

The ureter is freed proximally until the renal pelvis is exposed. During this step, it is important to watch for crossing vessels, which, if present, should be dissected off the UPJ (see the video below). The periureteral tissue should be preserved during dissection to avoid the complication of late ischemic stricture.

Robotic-assisted laparoscopic pyeloplasty: mobilization of crossing vessels.

The perirenal fat around the pelvis and retroperitoneal fat around the proximal ureter may make exposure difficult. Retraction sutures can be used to facilitate exposure of the UPJ without the use of another trocar or instrument. These may be sutured to surrounding fascia laterally to facilitate the rest of the surgery (see the video below).

Robotic-assisted laparoscopic pyeloplasty: retraction sutures.

In addition, the authors routinely place stay sutures on the renal pelvis and proximal ureter to facilitate handling of the tissues during dismembering of the UPJ (see the video below).

Robotic-assisted laparoscopic pyeloplasty: placement of stay sutures.

With the renal pelvis distended, the narrowed segment of the UPJ is identified. The cephalad robotic instrument is changed to Potts scissors. While the tissues are being handling with the stay sutures, the medial edge of the renal pelvis is incised 2 cm above the narrowed segment. The incision is carried along the anterior wall of the pelvis, extending inferolaterally until the lateral edge of the UPJ is reached.

The angle of the scissors is then turned inferiorly to spatulate the lateral wall of the ureter for about 1-3 cm, depending on the redundancy of the pelvis and ureter and the degree of tension. Dismemberment is completed by dividing the posterior wall of the renal pelvis parallel to the anterior wall. Spatulation of the ureter before dismemberment helps maintain the correct orientation of the ureter during spatulation. The UPJ remains attached to the ureter, serving as a handle for manipulation during anastomosis (see the video below).

Robotic-assisted laparoscopic pyeloplasty: dismemberment and spatulation.


Once the UPJ is dismembered, the next step is to make an assessment of the obstructive nature of any crossing vessels present. If necessary, the vessels may be transposed posteriorly. The ureter and the pelvis are then brought together for assessment of the degree of tension. Additional ureteral mobilization may be performed at this stage if necessary. Redundant pelvis may also be excised to achieve a funnel-shaped anastomosis.

The anastomosis is created with 4-0 or 5-0 polyglactin suture on an RB-1 needle. On the left side, starting with the ureter, the needle is passed from out to in at the apex of the spatulation. The suture is then passed from in to out at the lateral edge of the pelvis, and the knot is tied. On the right side, suturing is begun at the lateral edge of the renal pelvis from out to in, then continued from in to out through the ureteral spatulation.

In both cases, the posterior wall is first performed with a continuous stitch and ended medially with the needle on the outside. Interrupted sutures may also be used, especially for the posterior layer. Sutures should be carefully handled to ensure that they are not weakened or frayed.

After the posterior wall is completed, a final assessment of the patency of the anastomosis is made by using a 5-French infant feeding tube inserted alongside the stent into the ureter (see the video below). The renal pelvis is irrigated copiously to flush out any clot that might cause transient stent obstruction postoperatively.

Robotic-assisted laparoscopic pyeloplasty: infant feeding tube.

The proximal coil of the stent is replaced into the renal pelvis, and the anterior wall of the anastomosis is begun. A new suture is used for the anterior wall, starting laterally in a similar fashion and continued medially. The anterior suture is tied to the free end of the posterior suture to complete the anastomosis (see the video below).

Robotic-assisted laparoscopic pyeloplasty: anastomosis.

After the anastomosis has been completed and hemostasis ensured, all stay sutures are removed. The instruments are removed, and the arms are undocked from the ports. A 10-French or 15-French round drain is placed through one of the 8-mm ports and connected to bulb suction. The fascial openings at the 12-mm port sites are closed. In children, the fascial openings at all trocar sites are closed.



Intraoperative complications during RLP are rare, with frequencies ranging from 0-2%.[34, 35] Such complications include elective conversions, splenic and liver lacerations caused during instrument exchange, and minor bowel injuries. Major vascular injuries are extremely rare.


Urine leakage occurs during the early postoperative period in 2% of cases.[36] This is manifested as increased drainage output with a fluid creatinine concentration consistent with that of urine. It can be caused by transient obstruction by blood clot, a kinked stent, migration of the distal end of the stent up the ureter, or a disrupted anastomosis.

Abdominal radiography should be performed to confirm the position of the stent. A migrated or kinked stent should be adjusted ureteroscopically. Percutaneous nephrostomy may aid in additional drainage if necessary. A disrupted anastomosis is best treated by means of surgical revision. Intravenous antibiotic therapy should be instituted and computed tomography ordered with a view to draining any abscess or collection.


Persistent obstruction during follow-up renograms occurs in fewer than 10% of cases.[37] Treatment of persistent obstruction will depend on the surgeon’s experience and the patient’s preference. Both endopyelotomy and repeat pyeloplasty have been used in cases of secondary UPJO, with reported success rates exceeding 80%.[15, 45]