A Novel Method for Repositioning Suboptimally Preoperatively Placed Nephrostomy Tubes for Percutaneous Nephrolithotomy Without Renal Repuncture

Introduction

Puncturing the kidney and preparing a proper working tract are probably the most important steps in performing a successful percutaneous nephrolithotomy (PCNL) without complications. These steps referred to us as PCNL access involves the passage of a needle through the renal parenchyma and dilation of the entire length from the skin to the papilla by exercising longitudinal and/or radial forces. This procedure is potentially associated with significant risk of renal injury and bleeding, and the accuracy of its performance may dictate the entire course of the procedure. The ideal puncture should be in a posterior calix at the shortest distance from skin to papilla and aligned with the axis of that calix and its infundibulum. This provides an endoscopic approach to most of the stone burden without torquing the kidney during the manipulation of a rigid nephroscope.

Historically, both urologists and radiologists had contributed to establishment of the methodology and development of the devices needed for PCNL access. ¹ Despite the increasing number of endourologists performing accesses by themselves, there are still many institutions in which the access is performed by radiologists and the PCNL is carried out by urologists. ^{2 –4} It is our experience that when renal drainage is required in an acute setting (i.e., infection, renal failure, impacted stone, etc.), with the intention to leave a nephrostomy tube (NT) by the interventional radiologist without the input of the endourologist, these tubes are often not suitable for a subsequent percutaneous endoscopic approach. We describe a novel method of adjusting a suboptimally preplaced NT tract to meet the requirements for performing PCNL.

Patients and Methods

The registry of patients treated by PCNL in our institution was retrospectively analyzed from January 2002 until July 2017. All procedures were performed by an endourological team that had completed a fellowship program accredited by the Endourological Society. Access for PCNL was routinely achieved by the team as an integral step of the operation, but a minority of cases presented for PCNL with NTs that had been preplaced by an interventional radiologist in an acute setting. Those patients comprised our current study group and they were assessed for demographic and clinical data, suitability of the NT for PCNL in terms of tract length, location of entry into the kidney, and alignment of the NT with the axis of the calix.

In November, 2005, we began to use a novel approach that allowed NTs unsuitable for PCNL to be adjusted in correct positioning for performing PCNL. This approach consists of changing the place of the initial skin entry (ISE), shortening the length of the tract, and reducing the angle between the tract and the axis of the calix, while maintaining the place of entry in the kidney, thereby avoiding the need to repuncture. The procedure was done under general anesthesia as an integral part of PCNL. The five steps of this approach are:

Performance of a 5-mm skin incision at the ideal puncture location (IPL) as identified under fluoroscopic guidance (Fig. 1).

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FIG. 1.

(A) The ISE and the IPL along the guidewire that was passed through the unsuitable nephrostomy tube. (B) An Amplatz dilator placed in the adjusted tract. Note the position of the new tract in comparison to the initial tract (dotted line). IPL = ideal puncture location; ISE = initial skin entry.

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FIG. 2.

Blunt retroperitoneal dissection between the ISE and the IPL in relation to the lower calix. In this case, the distance between the ISE and the IPL was 5 cm.

This procedure was assessed for feasibility, time, distance between the IPL and ISE, difference between the old and new length of tract, changes of the angles between the old and new tract and the axis of the punctured calix, and outcome. In addition, we compared the demographics, clinical data, and outcomes of the PCNL patients with a preplaced NT with those of the PCNL patients without a preplaced NT.

Results

A total of 982 consecutive patients underwent PCNL during the study period of whom 23 (2%) presented with NTs placed in acute settings by an interventional radiologist. There were 16 (70%) males and 7 (30%) females with an average age of 64.7 years (range 34–88). Five (22%) of them harbored complete Staghorn stones. The primary indications for NT insertion were infection in 11 (48%) cases, obstructive uropathy in 7 (30%) cases, and intractable pain in 5 (22%) cases. All tubes were 8.2F Cope loop type (Cook^® Medical, Bloomington, IN), and they were inserted in an average of 3 weeks (range 2–7) before the surgery. They were located in the mid calix, lower calix, and renal pelvis in 6 (26%), 13 (57%), and 4 (17%) cases, respectively. The NT was suitable for PCNL in 5 (22%) cases, a new renal access was performed in 3 (13%), and the novel adjustment approach was performed in 15 (65%). The unsuitable ISE for PCNL was moved craniomedially for an average of 6 cm (range 4–7), thus shortening the working tract by an average of 2.5 cm (range 1.8–3.4). The new tract was aligned to the posterior calix axis, reducing the angle between them by an average of 65° (range 55–70) (Fig. 3). The average time for completing the procedure was 4 minutes. There were no complications related to repositioning. No cases of initial guidewire damage/kinking or of loss of access were encountered. The group with preoperative NTs was compared with the group without preoperative NT for the average operative time (105 minutes vs 112 minutes, respectively; p = 0.57), hospital stay (3.5 days vs 3.2 days; p = 0.65), complication rates (13% vs 14%; p = 0.57), and stone-free rates (87% vs 90%; p = 0.32). The patients who had preoperative NTs were significantly older (64.7 years vs 53.1 years; p < 0.01).

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FIG. 3.

The ISE and the IPL in relation to the upper urinary system at the end of the procedure.

Discussion

The methodology for percutaneous access followed by establishment of PCNL as the procedure of choice for large renal calculi are the result of a cooperative process of a group of visionary urologists and interventional radiologists. ^{1,5 –7} Radiologists' spatial, integrative, and anatomical understanding of X-ray fluoroscopy and ultrasonography, the location of the imaging machines in the radiological departments, their expertise in placing urgent NTs under local anesthesia, and collaboration with endourologists are the basis of their traditional involvement in preparing accesses for PCNL. ¹ The foundation of the Endourological Society and its educational programs resulted in the popularization of PCNL and the adoption of the entire technique, including the execution of the access, by urologists who completed dedicated fellowships. ^{8 –10} In addition, the use of virtual reality simulators for training urologists in PCNL access resulted in shortening the time to perform the procedure and time of radiation exposure, reduction in radiation dose, and improvement in correct calix puncture. ¹¹ One study that assessed the contemporary patterns of PCNL among certified urologists revealed that younger and fellowship-trained urologists are the primary users of PCNL, and that urologist-directed access has increased in the last decade. ³ According to a survey among Endourological Society members, the overall responders and fellowship-trained endourologists' rate of self-obtained access is 77% and 82%, respectively, and there is a trend toward an increase in these rates. ² However, these rates are much more modest in studies involving practices among urologists performing PCNL in general. Speed and colleagues ¹⁰ reported a rate of only 17% urologists performing accesses in a series of 40,501 PCNLs carried out in United States from 2003 to 2015. Those authors reported a 9.9% reduction in direct hospital cost when the access was performed by a urologist. A survey from United Kingdom revealed that 45% of the hospitals adopted a radiologist-made tract, 44% used a urologist-made tract, whereas the remaining 11% used both. ¹² A recent study that analyzed data from the British Association of Urological Surgeons registry reported a radiologist-obtained access rate of 66.3% cases, without differences in the outcome when compared with a urologist-obtained access group. ¹³ Other studies, however, showed better PCNL outcomes in terms of complications and stone-free rates when the access was done by an endourologist. ^12,14

In our opinion, the endourologists should independently perform the entire procedure in a single step. That is the current practice in our institution. We found that while most of the NT tracts that are performed in acute settings by the interventional radiologist without an endourologist's involvement are effective for drainage, they are not suitable for PCNL. The novel approach described in the current study can be easily and quickly applied by any qualified urologist and allows for the adjustment of a tract that is nonusable for PCNL by transposing it without repuncturing the kidney. We are aware that using guidewires in acute angles and against significant resistance may result in damage/kinking of the wire and loss of access. We believe that we avoided these situations by using tiny, nonkinking nitinol guidewires (e.g., Sensor 0.035″) and by grasping them only from their distal edge.

With regard to the risks of blunt retroperitoneal dissection, we relied on the experience we had gained by preparing the retroperitoneal space for retroperitoneal laparoscopic surgery, which implies a much larger blunt dissection of the retroperitoneal space than in our procedure. ¹⁵ We accept that an experienced endourologist may easily inject contrast through the preplaced NT and successfully achieve a new access. However, we believe that there are surgeons and situations in which our procedure can be beneficial for both patients and surgeons. Although these cases are rare (1.5% in our study), we believe that our novel method can be helpful and may have a place on the list of PCNL tips and tricks.

The relatively long hospital stay reported for the present study (around 3 days) is a result of analyzing procedures carried out over a 15-year period, including the transition from standard to tubeless and the conversion from prone to supine. During the past 7 years, 85% of our patients have been released home within 24 hours after the procedure, and we do not think that performing our novel procedure will affect the length of hospital stay either way. ¹⁶

Despite the feasibility, safety, and concept proved in our study, we are aware that this procedure is currently limited to cases of prone PCNL. Notably, the vast majority of interventional radiologists perform nephrostomy in acute clinical situations with the patient in the prone position, resulting in a posterior location of the NT point of entry. Although we think that a possible application of our method of employing a supine position is feasible, it will demand radical and multiple changes of the patient's positioning, causing unnecessary prolongation and increasing difficulty in initiating the PCNL. However, once interventional radiologists have been convinced to drain kidneys with the patient in a supine position, a conversion which seems logical to us, an eventual unsuitably preplaced NT could be adjusted for a supine PCNL. Other possible limitations in performing this procedure could be organ interposition (e.g., colon, liver, spleen) between the IPL and the kidney, and previous retroperitoneal operations that could have resulted in significant anatomical changes, interorgan adhesions, and fibrosis. These situations should be ruled out by anamnesis, physical examinations for scars and deformations, and cross-sectional imaging studies.

In conclusion, we present a novel method of adjusting preoperatively inserted NTs by repositioning their original entry location and tract to be suitable for PCNL while avoiding kidney repuncture. It is feasible, safe, and easy to implement, and it spares potential morbidity related to additional puncturing of the kidney.