Pediatric Robotic Assisted Laparoscopic Pyeloplasty

Abstract

Ureteropelvic junction obstruction (UPJO) is a common cause of hydronephrosis in the pediatric population. Management with an open dismembered pyeloplasty was first described by Anderson-Hynes in 1949; minimally invasive approaches have been increasingly utilized. In the subsequent text and accompanying video, we review the technique for dismembered robotic assisted laparoscopic pyeloplasty in the pediatric population. Large retrospective series demonstrate an over 90% success rate for robotic assisted laparoscopic pyeloplasty. Given success and complication rates are similar to an open approach, utilization of this approach will likely continue to increase.

Introduction

Ureteropelvic junction obstruction (UPJO) is a common cause of hydronephrosis in the pediatric population. Management with an open dismembered pyeloplasty was first described by Anderson-Hynes in 1949 with the first laparoscopic pyeloplasty performed in 1995 followed later by the robotic approach.¹ Despite an initial learning curve, robotic approaches have the potential benefits of shorter hospital stay and decreased narcotic use, with a similar success rate to the open approach.^2,3 The robotic platform has been increasingly utilized in recent years.⁴ In the subsequent text and accompanying video, we will review the technique for dismembered robotic assisted laparoscopic pediatric pyeloplasty.

Indications

UPJO may be identified based on prenatal ultrasound, incidentally, or due to symptomatic obstruction with potential symptoms including urinary tract infection, hematuria, kidney stones, or flank pain.⁵ Initial work-up is typically with ultrasound with subsequent evaluation with magnetic resonance urogram (MRU) or Technetium-99m mercaptoacetyltriglycine (MAG3) diuretic nephrography. The decision to offer pyeloplasty—via either an open or robotic approach—incorporates symptoms, differential renal function, and drainage curves with the primary goal of preventing declines in renal function or episodic pain due to kidney obstruction.

Preoperative Preparation

Patients consume a regular diet leading up to surgery with preoperative fasting determined by the anesthesia team. Antibiotics are given according to American Urologic Association guidelines. Necessary equipment is listed in Table 1.

Table 1.

Instruments for Robotic Pyeloplasty

Da Vinci Robotic System (Intuitive)
30-degree lens
3–8 mm ports
Airseal system (CONMED)
Monopolar curved scissors
Permanent cautery hook
Potts scissors
Maryland bipolar forceps
Angiocatheter
0 flattened permanent suture
5-0 or 6-0 dyed absorbable monofilament suture
Guidewire with hydrophilic tip
Double J ureteral stent or externalized pyeloureteral stent
Methylene blue

Surgeons can consider cystoscopy and retrograde pyelogram prior to the robotic portion of the surgery. Retrograde pyelogram can rule out concurrent abnormalities of the ureteropelvic junction such as a bifid collecting system or fibroepithelial polyps, evaluate the length of the obstruction, and confirm the adequacy of the distal ureter. This information may also be apparent from pre-operative work-up when cross sectional imaging is obtained. If cystoscopy is performed, a stent may be placed at that time to avoid subsequent percutaneous placement. Stent placement will decompress the renal pelvis—which can aid dissection in the case of a massively dilated renal pelvis with limited space or can hinder dissection if a floppy decompressed renal pelvis results.

A foley catheter is placed. An orogastric tube is placed to decompress the stomach prior to obtaining access.

Approach

A transabdominal approach is the most common approach to robotic pyeloplasty. A retroperitoneal approach has also been described—initially in 2005.⁶ Avoiding dissection in the peritoneal cavity minimizes the dissection and allows for potential conservative management of anastomotic leak.¹ While there is no consensus on the optimal approach, the transabdominal approach is performed more commonly and will be described in the subsequent text and accompanying video.

Patient Positioning

Considerable attention is paid to positioning to ensure the safety of the child and to optimize mobility of the robotic arms. Patients are positioned in the lateral decubitus position with the operative side up with the abdomen near the edge of the table.

Once in the appropriate position, the patient is secured to the table across the chest and hips. All pressure points and bony prominences are padded. One arm is typically positioned on an arm board and other is positioned at the patient’s side. The face and head are padded. After positioning is complete, the table is airplaned in both directions to test that the patient will be secure throughout the procedure and that all padding will remain in place.

Surgical Steps

Access and port placement

For initial access, the table is airplaned towards the side of interest until the patient is nearly supine. Initial access and port placement is in the inferior umbilical margin so that the incision will be hidden after healing.

Two additional ports are placed; a superior port is placed in the epigastric region in the midline and inferior port is placed in the midline suprapubic region, below the waistline so it is well concealed. The inferior port may be shifted towards the contralateral side if more working space is needed. Typically, three ports are used, and no assistant port is used. While all ports are placed near the midline, it is important to drape wide laterally on the ipsilateral side to allow for percutaneous placement of a hitch stitch and ureteral stent, which will be described later. Alternative port placement has been described with a port in the umbilicus and all remaining ports below the line of Pfannenstiel incision to minimize visible incisions.⁷

After port placement, the table is airplaned away from the side of interest so that the child is in the full flank position. The robot is docked over the ipsilateral surgical side with the base located behind the patient’s back. To increase working space in the abdomen, the surgeon should place only 1–2 cm of the robotic ports inside of the patient’s abdomen. “Burping” the ports also increases working space.

Initial dissection

Depending on the surgeon’s preference a Maryland bipolar and a Monopolar hook or curved scissors are used for this dissection. The hook can be useful for the ureteral dissection as it allows for safe handling of the ureter.

First, the colon is reflected medially to allow for visualization of the kidney and ureter. For patients with significant hydronephrosis, the colonic mesentery may be splayed out over the dilated renal pelvis. A transmesocolic approach is feasible in some cases, particularly on the left side with the benefits of shorter operative time due to limited dissection.⁸

After reflecting the colon, the ureter should be identified and dissected out down to the level of the iliac vessels and up to renal pelvis. The gonadal vessels should be dissected off the ureter as the ureter is often later transposed over the gonadal vessels to perform a tension free anastomosis.

After dissecting out the ureter, it should be traced up to the renal pelvis, and the renal pelvis should be dissected free. There may be a significant inflammatory thickening around the renal pelvis and ureteropelvic junction (UPJ), particularly in patients who have had prior urinary tract infections, stenting, or percutaneous nephrostomy tube placement. When dissecting the renal pelvis superiorly, the renal hilum is typically the cephalad extent of the dissection.

Hitch stitch

After dissecting out the ureter and renal pelvis, a hitch stitch (flattened size 0 permanent suture) is placed through the lateral abdominal wall and then through the renal pelvis. The hitch stitch is ideally placed through the superior medial renal pelvis beyond any planned pelvic reduction. In cases with challenging dissection, placing a hitch stitch early can be helpful as the additional traction allows for further dissection.

Dismembering and spatulating the ureter

The ureter is then dismembered, and the renal pelvis is reduced. The reduced pelvis serves as a handle for the subsequent steps before it is ultimately excised. When dismembering the ureter from the pelvis, leave sufficient renal pelvis medial to the lower pole calyces to avoid placing the anastomosis too close to the lower pole. We also confirm that the inferior end of the renal pelvis is aligned with the ostium of the lower pole calyx. This ensures that the anastomosis will not be placed too far posterior to the kidney once the hitch stitch is removed.

The ureter is spatulated in a posterolateral position. Potts scissors can be used to incise the ureter more finely. The hitch stitch should be intermittently relaxed to see the natural lie of the renal pelvis to ensure that the anastomosis will lie in a dependent position. When performing a left sided pyeloplasty it can be helpful to place the scissors in the left hand to perform spatulation.

Anastomosis and stent placement

The anastomosis is performed with interrupted sutures at the base. We use 5-0 or 6-0 dyed monofilament absorbable suture in most cases. Placing a feeding tube cut to about 4 cm into the ureter during the anastomosis may help ensure adequate bites of the ureteral urothelium with each stitch and prevent inadvertent “back walling” into the ureter. When the anastomosis is approximately 50% complete, a double-J ureteral stent is placed over a wire in an antegrade fashion through an angiocatheter placed in the lateral abdominal wall. The stent is typically inserted through the skin near the hitch stitch. Simultaneously, methylene blue is administered through the foley catheter so when the distal curl is appropriately positioned in the bladder, blue efflux will be seen through the stent. After passage of the stent, the anastomosis is completed. The excess pelvis is excised, and the superior portion of the pelvis may be closed to itself in a running fashion. We typically do not place a drain except in complex cases such as redo pyeloplasty or ureterocalicostomy.

External Pyeloureteral (EPU) Stent

We favor stenting anastomoses with either a double J stent or an EPU stent, however stentless robotic pyeloplasties are performed.⁹ An EPU stent has the potential benefits of avoiding bladder symptoms and additional anesthesia exposure from stent removal.¹⁰ The disadvantage is occasional dislodgement of the stent, especially if the coiled portion of the EPU stent, for example, retracts out of the renal pelvis. The EPU stent is inserted in a similar fashion, initially, as with the double-J stent. The distal limb of the EPU stent should reach the iliac vessels to prevent it from becoming dislodged and retracting into the renal pelvis. To prevent dislodgement, the EPU stent is secured with a purse string suture to the renal pelvis, to the peritoneal surface near its entry into the abdomen, and to the skin with a drain stitch.

Retrospective data has shown that compared to a double-J stent, EPU stents are a viable alternative with similar operative time, operative success, and complication rates.¹⁰ When an EPU stent is used, it is typically capped on post operative day (POD) 1-7 depending on surgeon preference and will be removed in 4-8 weeks.

UPJO Secondary to a Crossing Vessel

Compared to infants, UPJO in children and adolescents is more often due to extrinsic compression due to a crossing vessel. When a crossing vessel is suspected based on patient history or imaging, care should be taken with dissection near the lower pole. The crossing vessel should be mobilized off the UPJ and the renal pelvis. The ureter is transposed anterior to the crossing vessel after being dismembered. The anastomosis should be positioned inferior to the crossing vessel to avoid posterior compression on the UPJ from a pulsating crossing vessel.

Post-operative Care and Follow-up

While some surgeons perform robotic pyeloplasties outpatient,¹¹ we favor post-operative observation to ensure patients tolerate appropriate oral intake, void with safe residuals, and have adequate pain control. Pain is typically controlled with a non-opioid pain regimen.¹² The foley catheter is removed on POD1. Most patients meet clinical milestones for discharge on POD1.

Patients with a double-J ureteral stent will typically have it removed in 4-8 weeks. Following stent removal, patients are followed with ultrasound and with functional imaging as needed.¹³

Troubleshooting and Variations in Technique

Re-do pyeloplasty, patients with prior indwelling ureteral stents or percutaneous nephrostomy tubes, urinary tract infections, or other anatomical abnormalities such as duplex systems, malrotation or aberrant renal vasculature can create additional challenges. Surgeons can utilize several techniques to mitigate these challenges. In cases of difficult dissection due to extensive scarring from previous surgery or aberrant anatomy affecting orientation, using more than one hitch stitch can be useful to create an additional point of tension. Utilization of an assistant port or fourth robotic port to allow for additional retraction facilitates exposure. However, there must be careful consideration regarding port placement to prevent clashing of robot ports. Locations for additional port placement include between the existing ports in the contralateral side or in the ipsilateral lower quadrant.

In cases of a very large renal pelvis, pelvic reduction has been described but is not necessary to ensure a favorable outcome.¹⁴ Whether or not a reduction is performed, the focus should be on careful tissue handling and creating a wide, tension free anastomosis.

While the focus of this manuscript is on dismembered pyeloplasty, as this is the primary technique utilized, there have been several alternative techniques described for non-dismembered pyeloplasty. These are typically considered when there is not a crossing vessel and when dismembered pyeloplasty is problematic due to a small renal pelvis or inadequate ureteral length.¹⁵ These include a Foley Y-V pasty, a spiral flap pyeloplasty, or a vertical flap pyeloplasty.¹⁵ These alternative techniques are not as well studied. Single institution retrospective studies evaluating laparoscopic and robotic Foley Y-V non-dismembered pyeloplasty describe success rates of 43-100%.^15
–17 There have been no randomized studies comparing robotic dismembered pyeloplasty to robotic non-dismembered pyeloplasty.

In challenging redo cases, particularly a short ureter or when the renal pelvis is inaccessible due to scarring or a lack of extra renal dilation of the renal pelvis, we believe that a ureterocalicostomy should be considered as a reliable technique offering acceptable results.¹⁸

Clinical Outcomes

Surgical success following robotic pyeloplasty is variously defined across studies. Definitions include improvement in symptoms, improved or stable hydronephrosis on renal ultrasonography, or improved drainage curves on functional imaging. Success rates range from 91-100% (Table 2) in retrospective studies with follow-up between 10 and 31 months.^{3,19

–25}

Table 2.

Summary of Select Studies Reporting Success Rates for Pediatric Robotic Pyeloplasty^a

Study	Patients, n	Median age	Definition of success	Success, %	Median follow-up, months
Minnillo, 2011¹⁹	155	9.9 years	Improved symptoms, improved hydronephrosis and/or improved drainage parameters with ultrasound and/or renography	96	31.7^b
Riachy, 2013²⁰	46	8.8 years	Resolution of symptoms, hydronephrosis improved by one grade, stable US with symptom resolution or improved drainage curve on renography	100	22
Lee, 2006³	33	7.9 years^c	Symptom resolution, significant and persistent improvement in hydronephrosis and/or t1/2 less than 10 minutes	94	10^b
Murthy, 2015²¹	52	6.8 years^c	Relief of associated symptoms with improved or stable ultrasound findings	94	14.3^b
Mittal, 2021²²	276	5 years	Resolution of symptoms, improved hydronephrosis and no need for additional procedures	95	18.1
Lai, 2023²³	327	4 years	Improvement in hydronephrosis without need for reoperation	94	25.1
Avery, 2015²⁴	60	7.3 months^c	Resolution or improvement of hydronephrosis grade or improved drainage curve on MAG3 renal scan	91	12
Rague, 2022²⁵	83	7.2 months	Radiographic improvement in hydronephrosis	91	16.1

For studies including robotic and open pyeloplasties, data from the robotic pyeloplasties is reported in this table.

Mean follow-up.

Mean age.

Complication rates are similar to open pyeloplasty with a minority of patients experiencing a minor complication.^3,21,25,26 Focusing on the larger cohorts of children undergoing robotic pyeloplasty, Lai et al. (2023) reported a 6.1% 90-day complication rate with 4 Clavien I complications, 2 Clavien II complications and 14 Clavien IIIb complications (8 stent related complications, 4 port-site hernias, 2 urine leaks).²³ In the primary pyeloplasty cohort reported on by Mittal et al. (2021), 13% experienced a complication within 30 days; Clavien II complications were most frequent.²²

While utilization of robotic pyeloplasty has increased in older children, adaptation of this platform for surgery in infants has been slower.⁴ Multiple studies, however, have demonstrated the feasibility and safety of this approach.^24,25 Additional technical considerations for infant pyeloplasty are listed in Table 3.

Table 3.

Additional Technical Considerations for Infant Pyeloplasty

Positioning	Careful positioning to avoid iatrogenic injury
Port placement	Supraumbilical port placement may allow for more space for the inferior port
	Place the inferior most port on the contralateral side to increase working room
	Burp ports to increase working space
Anastomosis	Use of smaller absorbable monofilament suture for the anastomosis
Stent placement	EPU stent if ureterovesical junction cannot accommodate a double J ureteral stent

Summary

Robotic assisted pyeloplasty is a safe and effective surgery for management of UPJO in the pediatric population, including children less than one year of age. Given success and complication rates are similar to an open approach, utilization of this approach will likely continue to increase.

Footnotes

Authors’ Contributions

M.F.D. contributed by writing and preparation in original draft. A.K.S. worked on writing, reviewing and editing the manuscript. S.M. helped in writing, reviewing and editing. A.R.S. performed conceptualization, writing, reviewing, editing and supervision.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

No funding was received for this article.

Supplementary Material

Supplementary Data S1

Abbreviations Used

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