Pyeloplasty, upper tract stone surgery, and renal surgery for congenital anomalies

Indications and contraindications for robotic pyeloplasty

The indications for robotic-assisted laparoscopic pyeloplasty are the same for any pyeloplasty, regardless of approach. Indications for pyeloplasty in adults can be categorized as either clinical or radiological. PUJ obstruction is a radiological diagnosis, made with a contrast enhanced CT scan showing hydronephrosis and a classic tapering at the PUJ and functional nucleotide imaging such as a mercaptoacetyltriglycine (MAG 3) scan with the addition of a diuretic. Demonstration of functional obstruction by a T ½ of greater than 20 minutes with or without a differential function of less than 40% is the radiological indication for pyeloplasty.

Once the diagnosis has been made radiologically, the clinical indications for pyeloplasty are flank pain, recurrent upper urinary tract infection, development of renal calculi, and worsening renal function. Pain is often described after a significant fluid or diuretic challenge such as with alcohol or caffeine, known as Dietl crisis.

In the setting of a poorly or nonfunctioning kidney (<10% to 15% split function), observation or nephrectomy may be preferred. Other contraindications include all contraindications to robotic assisted/laparoscopic surgery, active infection, suspicion of an upper tract urothelial malignancy, and an intrarenal pelvis ( Table 22.1 ). ^,

Indications and contraindications for robotic pyelolithotomy and nephrolithotomy

Due to the lowering costs and the increasing ubiquity of robotic-assisted surgery in urologic practice, coupled with the rising incidence of stone disease, indications and application for the operating robot in upper tract stone surgery continue to evolve. Current guidelines for the management of large upper tract calculi are well established. Both the American Urological Association (AUA) and the European Association of Urology (EUA) recommend PCNL over URS or shock-wave lithotripsy (SWL) as first-line management for symptomatic stones greater than 20 mm and lower pole stones greater than 10 mm. ^, Traditionally, an open approach was utilized for stones not amenable to PCNL or with previously failed endoscopic extraction. Laparoscopic and subsequently robotic stone removal emerged as alternatives to an open approach, avoiding the morbidity of a large incision. These techniques have been utilized when stones and anatomic defects, such as PUJ obstruction, occur concomitantly. Despite mounting data, the precise indications for the use of robotics as a first-line approach for upper tract stones without reconstruction have yet to be fully codified.

The upper limits for PCNL with regard to stone size or density are not well defined, and a robotic approach has demonstrated efficacy for solitary large, hard, or complex upper tract stones. In 1994 Gaur et al. first reported on laparoscopic pyelolithotomy with a subsequent small series confirming its feasibility with concomitant PUJ repair. Robotic pyelolithotomy (RPL) series began appearing in the literature after 2005, with indications including concomitant upper tract reconstruction, failed prior intervention, and primary treatment for large staghorn stones without upper tract abnormality.

Staghorn kidney stones have one of the lowest clearance rates reported with PCNL and more often require multiple puncture sites which carry an increased risk of bleeding and need for transfusion. Badani et al. have demonstrated excellent results with primary robotic stone removal of staghorn calculi with particularly high clearance rates for partial staghorn stones. ^, Similar success for partial staghorn clearance has been shown in subsequent series. ^,

Infectious or struvite stones are very frequently staghorn in configuration. These stones have a high likelihood of sepsis and subsequent growth when fragments are left behind. As such, guidelines recommend that these patients be rendered completely stone-free. RPL traverses the renal pelvis providing a low-pressure system for stone extraction, potentially without fragmentation minimizing potential septic complications. Swearingen et al. demonstrated excellent efficacy for staghorn calculi, as well as one case of a gas-containing stone, where robotic removal was presumably chosen to mitigate fragmentation, and therefore infection risk.

Patients with large kidney stones and concurrent anemia and/or chronic kidney disease (CKD) may also be potential candidates for RPL, avoiding exacerbation of these comorbidities. Access through the renal parenchyma can decrease glomerular filtration rate (GFR) in preexisting CKD or when multiple puncture sites are needed and can cause bleeding due to the high vascularity of the kidney. ^{, ,} Several modern robotic series have reported excellent stone-free rates with minimal to no reduction in GFR and low transfusion rates. ^{, ,}

Another potential indication for RPL is large or complex stones in obese patients. While direct comparison studies have not been conducted, increased BMI can affect PCNL with longer operative times, inferior stone-free rates, and higher repeat intervention rates, while obesity has not demonstrated a difference in the outcomes of robotic renal surgery. ^,

Other, though less frequent, indications for upper tract robotic stone extraction include symptomatic anterior calyceal diverticulum with stones, ectopic kidneys with large stone burden not amenable to PCNL, and large impacted ureteral stones with or without concomitant strictures. These are relatively rare instances, and the decision to use the operating robot should be made on a case-by-case basis with the relevant anatomy and operating surgeon’s skill set considered.

A full list of indications for robotic stone removal can be found in Table 22.2 .

We do not recommend robotic stone surgery as first-line therapy for clinically straightforward stones less than 2 cm which meet well-established criteria for URS, SWL, or PCNL. Relative contraindications to RPL include large calyceal stones with narrow infundibula in the upper and/or lower pole, which present a challenge to robotic removal without fragmentation due to poor access and visualization. Complete staghorn stones with large calyceal components also demonstrated lower stone-free rates in multiple series. ^, In the largest series to date with RPL for primary stone removal, only 5 out of 70 patients required secondary procedures for incomplete removal; 4 out of those 5 were stones with some form of calyceal component. While robotic anatrophic nephrolithotomy has been described for complete staghorn stones, it is not recommended as it can be technically challenging with a potential for significant blood loss and a low reported stone-free rate of 28.6%.

Collecting systems with many dispersed stones can make complete clearance difficult with a robotic approach. Bedside pyeloscopy with laser lithotripsy can be performed through a robotic port. Roth et al. reported lower stone-free rate compared to other studies, as well as one instance of urosepsis. Notably, in this series, most patients had multiple stones, and concurrent endoscopy was performed which may have been the reason for the infectious complication. Nevertheless, multiple stones are likely best approached with other modalities of lithotripsy for the highest chance of success.

Further contraindications include lack of surgeon experience with the operating robot as well as patients with significant prior abdominal (or retroperitoneal) surgical history, scarring or fibrosis. When the surgeon can anticipate poor surgical planes, aberrant anatomy, and/or difficult robotic maneuverability intraoperatively, other approaches are best explored.

Preoperative assessment

Patients should be counseled on the risks, benefits, and alternatives to the proposed procedure as well as expected outcomes and potential complications. The need for a ureteric stent as well as common side effects should be thoroughly explained. The extent of preoperative blood work and the need for medical clearance will vary with a patient’s comorbidities; at a minimum, a basic metabolic panel and urine culture are necessary. A noncontrast computer tomography (CT) scan with three-dimensional (3D) reconstruction is imperative in planning renal stone surgery ( Figs. 22.1 and 22.2 ), particularly in cases where there is more than one stone. For pyeloplasty, a contrast study, either CT or magnetic resonance imaging (MRI), is essential to outline the relevant anatomy and identify any lower pole crossing vessels.

Patient preparation and positioning

The patient is induced under a general anesthetic and depending on the preoperative workup, either placed in lithotomy for cystoscopy and retrograde pyelogram or into a modified lateral decubitus position with gel roll supports posteriorly. The authors prefer to place a stent antegrade intraoperatively. The ipsilateral leg is extended and supported with a pillow and the contralateral leg is flexed with adequate padding beneath the knee and lateral malleolus of the ankle. The ipsilateral arm is draped over a pillow or in a gutter and secured with tape. The contralateral arm is extended on an arm board and an axillary roll placed if required. The patient is secured at the hips and thorax with tape. An upper body “Bair Hugger” is applied for warming. The patient’s abdomen is shaved and prepped to include the genitalia to allow access to the urethra intraoperatively. Draping is performed to allow exposure of above.

Port placement and robot docking: Transperitoneal approach

We favor a transperitoneal approach as this allows better access to the renal pelvis. Depending on body habitus and the extent of renal pelvis dilation, ports may be shifted slightly more caudal compared to a standard set-up for robotic renal surgery. In general, ports are placed in a straight line beginning at the lateral border of the rectus (about 6 cm lateral to the midline). For very thin/small patients, ports may be placed in the midline. For those with a larger body habitus, ports may be shifted laterally to the mid-clavicular line. A 5 mm or 8 mm AirSeal assistant port is placed through the umbilicus. Surgery is performed with insufflation set to 12 mmHg. The robot is docked perpendicular to the patient, ideally from the posterior aspect. A list of recommended equipment is provided in the box that follows.