Simultaneous combined use of flexible ureteroscopy and percutaneous nephrolithotomy to reduce the number of access tracts in the management of complex renal calculi

Authors


Glenn M. Preminger, Division of Urology, Box 3167, 1572D White Zone Duke South, Duke University Medical Center, Durham, NC 27710, USA.
e-mail: glenn.preminger@duke.edu

Abstract

In a joint study between Duke University, North Carolina and London, a simultaneous combination of flexible ureteroscopy and percutaneous nephrolithotomy was used to reduce the number of access tracts required to manage complex renal calculi. This was found to be an effective method which reduced morbidity and blood loss, without increasing operating time, but without increasing stone-free rates.

Authors from the USA carried out an experimental study to determine whether an electrode array with a bipolar radiofrequency ablation energy source could be used for partial nephrectomy, simultaneously ablating and coagulating renal tissue. They found that this system could indeed be used in a bloodless fashion with no collecting system injury.

OBJECTIVE

To present early experience in managing complex renal calculi using a combined ureteroscopic and percutaneous approach, as complex and branched renal calculi often require multiple access tracts during percutaneous nephrolithotomy (PNL), and the combined use of flexible ureteroscopy and PNL has the potential to reduce the inherent morbidity of several tracts.

PATIENTS AND METHODS

The study included seven patients (mean age 54 years) with multiple, branched, large-volume renal calculi suitable for management with PNL. Preoperative data, including patient demographics, stone location and stone surface area, were recorded. After informed consent, the patients underwent combined PNL and ureteroscopy in one session. Intraoperative data, including the location of PNL puncture sites, operative duration and complications, were analysed. Stone-free rates were determined by follow-up imaging at 3 months.

RESULTS

All patients had either two or more stones in separate locations in the collecting system, or staghorn stones involving multiple calyces. The mean stone burden was 666 mm2. All patients had only one percutaneous access tract. The mean operative duration was 142 min and the mean blood loss 79 mL. Two patients had small residual stones (<3 mm), that required ureteroscopic intervention as they failed to pass spontaneously by 3 months after the initial combined procedure. The convalescence was similar to that in our current PNL practice; imaging showed that five of the patients were stone-free.

CONCLUSIONS

Combined PNL and ureteroscopic management can effectively reduce the number of percutaneous access tracts which would otherwise be required for managing complex and branched renal calculi, as stones in an unfavourable location relative to the access tract can be relocated and fragmented within easy reach of the single nephrostomy tract. This manoeuvre reduces potential patient morbidity and blood loss but with no significant effect on stone-free rates and operative durations.

Abbreviations
PNL

percutaneous nephrolithotomy

FU

flexible ureteroscopy(ic).

INTRODUCTION

Percutaneous nephrolithotomy (PNL) is currently the treatment of choice for managing complex renal calculi. Because of the anatomical variation of calyces, full access to the entire intrarenal collecting system through one access tract can be technically challenging, even when a combination of rigid and flexible instruments is used through one tract. Thus, these complex renal calculi, which can extend into multiple calyces or have peripheral satellite calculi, often require several access tracts during PNL. However, these additional tracts can be associated with greater operative morbidity and postoperative discomfort.

Advances in flexible ureteroscopic instrumentation and holmium laser lithotripsy now allow retrograde access to the entire intrarenal collecting system. Although not ideal for managing a large stone burden, flexible ureteroscopy (FU) can be used adjunctively to reach peripheral renal calculi. We therefore evaluated the feasibility of combined FU and PNL to decrease the number of percutaneous access tracts during the surgical management of complex renal calculi.

PATIENTS AND METHODS

Patients with multiple or branched renal calculi, who would otherwise have been treated with PNL using several access tracts, were included in the study. Informed consent was obtained for both FU and PNL. Preoperative imaging studies, which included IVU or CT, were evaluated for stone location, extension and surface area (determined by multiplying stone length by width on two-dimensional radiographic studies).

Surgical technique

After retrograde pyelography and placing a safety guidewire, a 12/14 F ureteric access sheath was advanced into the proximal or mid ureter, allowing easy passage of the 7.5 F flexible ureteroscope into the collecting system. The renal stone(s) and collecting system were carefully inspected. Stones in the peripheral calyces, which would have required a second or third nephrostomy access, were fragmented with a 200 µm holmium laser fibre. Alternatively, a 2.4 F Nitinol stone basket was used to transfer satellite calyceal stones into the renal pelvis for concomitant laser lithotripsy or for easier access during sequential PNL. After the targeted calyx had been cleared of stone fragments the patient was then placed prone and a standard percutaneous approach used [1,2]. A combination of ultrasonic, pneumatic and holmium laser contact lithotripsy was used to completely fragment the large-volume portion of the stone and the satellite fragments that had been repositioned into the renal pelvis [3]. At the end of procedure, the collecting system accessible to the rigid and flexible nephroscope was examined for potential fragments. A 10 F Cope loop or 18 F Foley nephrostomy tube was placed through the percutaneous access tract.

Analgesics were administered ‘as needed’; most patients were discharged 2 days after surgery, following removal of their nephrostomy tube, provided no significant residual stone was seen on the X-ray. Patients returned for a follow-up assessment with IVU, plain abdominal film and renal ultrasonography or CT, at 3 months.

RESULTS

The data for the seven patients (five men and two women; mean age 54 years, range 34–78) treated by combined PNL and FU are shown in Table 1. All patients had two or more stones in separate locations in the collecting system or a single branched renal calculus involving more than one calyx. The mean (range) stone burden was 666 (100–2700) mm2. All patients had only one percutaneous access tract. The mean operative duration was 142 (68–240)  min; the duration with the combined approach was not significantly different from our previous experience with standard multiple access PNL (166 min, P = 0.36) [3]. The mean blood loss using the combined approach was 79 (0–150) mL, which was significantly less than in our patients undergoing multiple-puncture PNL (345 mL, P < 0.05) [3].

Table 1. 
The characteristics of the patients and stones, with the treatment and outcome
Age/sexStone locationStone area, mm2PunctureOperative duration, minFollow-up
34/MSeveral stones throughout kidney20 × 20 = 400Upper pole × 1 Supra-12th227Residual small fragments largest 3 mm diameter
67/FTwo stones10 × 25 +Upper pole × 1123Stone-free
Upper pole and lateral8 × 10 = 330Supra-12th  
43/FTwo stones upper and lower poles10 × 10 + 20 × 20 = 500Lower pole × 1 subcostal 82Stone-free
55/MInterpolar and lower pole10 × 23 = 230Lower pole × 1 subcostal128Stone-free
42/MComplete staghorn90 × 30 = 2700Middle calyx × 1 subcostal2402 mm fragment lower pole
65/MUpper anterior calyceal diverticular10 × 10 = 100Middle calyx × 1 subcostal124Stone-free
78/MComplex branched staghorn60 × 15 = 900Middle calyx × 1 subcostal 68Stone-free

Two of the present patients had small asymptomatic residual calculi (<3 mm); one of these had a solitary kidney and FU was used ≈ 3 months after the initial combined procedure, and the other was managed expectantly and remains asymptomatic at 6 months of follow-up. The imaging studies after surgery showed that five of the seven patients were stone-free after combined PNL and FU.

DISCUSSION

PNL is currently the treatment of choice for large or complex renal calculi [4]. Several techniques have been described for percutaneous access, but inherent to each are specific limitations and risks. For instance, upper or interpolar access may be more difficult due to angular limitations of the calyces and ribs. However, supracostal access was reported as one of the most effective approaches, despite the greater risk of intrathoracic complications [2,5,6]. Access to all the calyces through one percutaneous tract may be difficult due to the peculiar anatomical structure of the collecting system. Accordingly, complex and branched renal calculi occupying several calyces often require multiple access tracts during PNL. Several PNL tracts are required in 20–58% of percutaneous procedures [2,7,8]. Furthermore, multiple access tracts may be associated with greater renal parenchymal injury, a doubling of blood loss, and greater discomfort after surgery than in patients requiring only one tract [9,10].

FU has been used successfully to access and treat complex renal calculi [4,11,12], but the small working channels of flexible ureteroscopes had limited the usefulness of adjunctive instrumentation that allows concurrent stone fragmentation and removal. Hence, the ureteroscopic management of a large stone burden often requires prolonged surgery, with either repeated passage of the FU combined with ESWL co-fragmentation or multiple sessions of treatment, often resulting in less than satisfactory stone-free rates.

However, recent advances in FU instrumentation and adjunctive equipment have facilitated the removal of renal calculi regardless of location. Routine use of a ureteric access sheath facilitates the passage of the FU, while allowing the removal of a larger stone burden, and at the same time maintaining minimal intrarenal pressures [13–16]. Wherever possible, in situ intracorporeal lithotripsy with the holmium laser can be used to reduce the stone burden that has to be actively removed. Alternatively, the peripheral stone burden can be translocated into the renal pelvis, using a 1.9 F or 2.4 F Nitinol basket, for easier PNL access or for intracorporeal lithotripsy [17–20].

Despite retrograde irrigation, stone fragments often fail to clear completely after intracorporeal lithotripsy. Residual stones may grow, become symptomatic and require further intervention [21,22]. Alternatively, PNL combined with retrograde FU offers a larger-bore access that can allow efficient removal of these remaining fragments.

In conclusion, the current approach tested here combines the advantages of both PNL and FU to effectively decrease the number of percutaneous access tracts which would be otherwise required for managing complex and branched renal calculi, thereby reducing blood loss, potential morbidity and discomfort associated with multiple tracts, but with no significant effect on stone-free rates or operative duration.

CONFLICT OF INTEREST

A. Patel and D. Albala are consultants for ACMI. G. Preminger is a consultant for Olympus and Boston Scientific.

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