Radially expanding single-step nephrostomy tract dilator

Fluoroscopy guided percutaneous renal access in prone position

Percutaneous nephrolithotomy is a very commonly done procedure for management of renal calculus disease. Establishing a good access is the first and probably the most crucial step of this procedure. A proper access is the gateway to success. However, this crucial step has the steepest learning curve for, in a fluoroscopy guided access, it involves visualizing a three dimensional anatomy on a two dimensional fluoroscopy screen. This review describes the anatomical basis of the renal access. It provides a literature review of all aspects of percutaneous renal access along with the advances that have taken place in this field over the years. The article describes a technique to determine the site of skin puncture, the angle and depth of puncture using a simple mathematical principle. It also reviews the common problems faced during the process of puncture and dilatation and describes the ways to overcome them. The aim of this article is to provide the reader a step by step guide for percutaneous renal access.

A comparison of metal telescopic dilators and Amplatz dilators for nephrostomy tract dilation in percutaneous nephrolithotomy

BACKGROUND AND PURPOSE

Nephrostomy tract dilation is one of the important steps in percutaneous renal surgery. We present our experiences with using Amplatz and metal telescopic dilators (Alken) to create a percutaneous tract and compare the advantages and risk factors of both procedures.

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 173 patients who had undergone 188 percutaneous nephrolithotomy procedures between April 2007 and December 2010. The nephrostomy tracts had been created by using Amplatz (67 cases) or Alken dilators (121 cases). Total operative time, scope time, tract formation time, decrease in hemoglobin concentrations, blood transfusion rates, tract dilation failures, and the cost of both systems were compared between the groups.

RESULTS

There were no statistically significant differences in total operative time (103.3 ± 46.5 vs 99.1 ± 44.4 min, P=0.583), scope time (5.23 ± 3.06 vs 5.28 ± 2.52 min, P=0.732), decrease in hemoglobin concentration (-1.5 ± 1.2 vs-1.3 ± 1.1 mg/dL, P=0.230), blood transfusion rates (13.4% vs 11.6%, P=0.709), and tract dilation failure rates (6.0% vs 1.7%, P=0.107) for Amplatz and Alken dilation groups, respectively. A shorter tract formation time (6.56 ± 3.04 vs 5.42 ± 3.07 min, P<0.001) was observed in the Alken dilation group. The approximate costs per each case were $220 and $7.25 for Amplatz and Alken dilation groups, respectively.

CONCLUSIONS

The Alken dilation technique produces similar results to the Amplatz dilators in terms of efficiency, safety, and total operative time. Notwithstanding, it is more cost-effective in comparison.

Renal parenchymal damage after percutaneous nephrolithotomy with one-stage tract dilation technique: a randomized clinical trial

PURPOSE

To compare the effects of one-stage vs gradual dilation techniques during percutaneous nephrolithotomy (PCNL) on postoperative renal scar formation and overall renal function.

PATIENTS AND METHODS

Of 152 adult patients who underwent surgery during the study period, 48 were randomized into two groups. In group 1 (n=19), gradual tract dilation with Alken metallic dilators was used, and in group 2 (n=29), one-stage tract dilation was used. We compared patient demographics, intraoperative and preoperative parameters, postoperative overall renal function, and renal scar formation on the target renal pole.

RESULTS

Access time (P=0.001; 95% confidence interval [CI]: 3.19-6.30) and radiation exposure during access (P=0.03; 95% CI: 0.03-0.66) were significantly shorter in group 2. In group 1, the decrease in mean technetium-99m dimercaptosuccinic acid (99m-Tc DMSA) uptake from 44.1±20.1% to 43.4±19.6% 4 weeks postoperatively (-0.7%±0.5%; P=0.27; 95% CI: -0.56-1.93) was not significant. In group 2, however, there was a significant decrease in post-PCNL 99m-Tc DMSA uptake 2 (-2.4±0.3%, from 50.1±13.5% to 47.7±13.8%; P=0.001; 95% CI: 1.13-3.66). Four weeks after surgery, new scar formation or progression of the preoperative scar at the site of access were seen in 14 of 29 (48.3%) patients who were treated with one-stage dilation whereas only 2 of 19 (11.0%) patients who were treated with gradual dilation developed new scarring at the access site (P=0.007).

CONCLUSION

Although the one-stage tract dilation technique reduced radiation exposure and access time, in the short term, it may cause more parenchymal damage than the gradual dilation technique.

Two contemporary series of percutaneous tract dilation for percutaneous nephrolithotomy

Dilation of the tract for percutaneous nephrolithotomy can be performed with three different basic techniques. A retrospective outcome analysis of two techniques-metal telescoping dilation and balloon dilation-in a contemporary series of two European departments shows no significant difference in morbidity related to the dilation procedure. A literature survey that concentrates on publications with a focus on tract dilation shows that balloon dilation is the most frequently performed, but the morbidity reported for the different techniques appears identical. The three standard techniques have been developed more than 20 years ago. Very few new techniques have been added.

Balloon dilatation versus Amplatz dilatation for nephrostomy tract dilatation

PURPOSE

In this study, we present our experience using balloon and Amplatz dilatation to establish a percutaneous tract. We also discuss advantages and risk factors of both techniques.

MATERIALS AND METHODS

We retrospectively reviewed medical records of 229 patients who had undergone 235 percutaneous nephrolithotomy procedures. The nephrostomy tract had been dilated using a balloon (42 patients) or Amplatz (187 patients) dilator. Total operating time, preoperative and postoperative hemoglobin concentrations, number of tracts required, stone burden, blood transfusion rates, tract dilatation failures, and the cost of the dilatation system were compared between the groups.

RESULTS

There were no statistically significant differences in operative time (85.7+/-43.2 v 86.3+/-41.2 minutes; P=0.42), preoperative hemoglobin concentration (14.1+/-1.1 v 13.8+/-1.4 mg/dL; P= .153), postoperative hemoglobin concentration (11.6+/-1.7 v 11.2+/-1.5 mg/dL; P= .601), or blood transfusion rate (18.6% v 21.3%; P= .687) between the two groups. Also, there were no differences in failure rates between the two groups.

CONCLUSIONS

The Amplatz dilator is comparable with the balloon dilator with regard to efficacy, speed, and safety. The Amplatz dilator is more cost-effective than the balloon dilator. However, kidney hypermobility may be a significant problem during Amplatz dilatation.

Innovative Metal Dilators for Percutaneous Nephrostomy Tract: Report on 546 Cases

OBJECTIVES

A retrospective study was conducted to evaluate the efficacy and safety of creating a percutaneous nephrostomy tract for stone removal with innovative metal dilators.

METHODS

A total of 546 percutaneous nephrolithotomies was performed at Chiayi Christian Hospital from January 2001 to December 2005. Innovative metal dilators were used to create 546 percutaneous nephrostomy tracts in 520 patients. Several patients had multiple percutaneous nephrostomy tracts. Patient age, stone burden, operative time, stone-free rate, postoperative hospital day, postoperative urinary tract infection rate, and blood transfusion rate were recorded using retrospective chart review.

RESULTS

The dilation time was less than 15 minutes. The average patient age was 53.7 +/- 13.1 years, and the average stone size was 3.5 +/- 2.0 cm. The average operative time was 100 +/- 45 minutes. The average postoperative hospital stay was 4.4 +/- 2.6 days. The overall stone-free rate was 84.4% (461 of 546). The stone-free rate was 99% (142 of 143) for upper ureteral stones, 87% (268 of 305) for renal stones, and 52% (51 of 98) for complete staghorn stones. The blood transfusion rate was 2.5% (14 of 546). The postoperative urinary tract infection rate was 8.6% (47 of 546). Of the 520 patients, 6 had pleural effusion and 1 had pneumothorax.

CONCLUSIONS

Our innovative metal dilators saved time, resulted in less bleeding, and successfully provided one-stage tract creation in 520 patients. The dilation system also allowed the use of a ureteroscope to check the entrance tract to reduce complications.

Techniques for fluoroscopic percutaneous renal access

PURPOSE

Percutaneous nephrolithotomy has undergone considerable evolution since its introduction in the 1970s, which has been driven by advances in access techniques, instrumentation and endoscopic technology. Recent reports suggest an increase in the number of percutaneous stone treatments being performed. However, despite the increasing use of percutaneous nephrolithotomy a minority of urologists obtain their own access. We reviewed the techniques for performing safe and effective percutaneous renal access.

MATERIALS AND METHODS

A literature search using Entrez PubMed was performed. All relevant literature concerning techniques for fluoroscopic percutaneous renal access published within the last 20 years was reviewed.

RESULTS

The success of percutaneous nephrolithotomy is critically dependent on achieving suitable percutaneous access. The ideal site of percutaneous puncture should be selected to maximize the use of rigid instruments, minimize the risk of complications and attain stone-free status. Familiarity with basic renal anatomy is essential to obtain access safely. Adherence to basic principles allows the establishment of percutaneous access in a straightforward and efficient manner. Certain clinical situations may require special access techniques.

CONCLUSIONS

Percutaneous nephrolithotomy is the treatment of choice for complex stone disease. While the efficacy of percutaneous nephrolithotomy relies on the establishment of effective percutaneous access, there are considerable advantages for the urologist able to achieve access.

Novel everting urologic access sheath: potential advantages of decreased cellular advancement

BACKGROUND AND PURPOSE

Axial forces are imposed on the urothelium during advancement of instruments across the urinary tract, potentially transferring cellular debris, bacteria, or urothelial carcinoma from one anatomic location to another. A prototype access sheath (Cystoglide; Percutaneous Systems, Mountain View, CA) was created that everts and radially dilates but does not provide axial forces during deployment that can be used in a variety of anatomic systems. We created a urinary-tract model to evaluate the in-vitro advancement of cells to compare this technology with using instruments alone.

MATERIALS AND METHODS

Blocks of sterile agar were created with 17F tracts of three lengths (2.7, 5.5, and 11 cm) with 5 mL of Luria-Bertani broth/ampicillin solution in a well at the end. The tips of a Cystoglide sheath and a traditional urologic instrument of the same diameter were dipped into a suspension of ampicillin-resistant Escherichia coli and advanced through the tracts. After a 10-second exposure, 4 mL of broth was collected and cultured. Bacterial growth was compared by measuring the optical density (OD) of the broth at multiple time points.

RESULTS

The mean overall OD of the broth was significantly lower (P < 0.001) in the novel-sheath cultures than with a traditional instrument for all advancements at all tract lengths.

CONCLUSION

The Cystoglide sheath significantly reduces the advancement of cells within an artificial urinary tract compared with a non-everting instrument. Clinical studies are needed to assess the utility of this technology in vivo.

A Novel Single Step Percutaneous Access Sheath: The Initial Human Experience

PURPOSE

A novel 1-step percutaneous access sheath NS has been developed that allows the insertion of a dilating balloon and renal access sheath in a single step. We present the initial human experience with this sheath.

MATERIALS AND METHODS

We performed a retrospective chart and database review of the initial 30 consecutive patients undergoing percutaneous nephrostolithotomy using the NS. Data collected included patient demographics, operative and recovery parameters, and complications.

RESULTS

Mean patient age was 50.4 years (range 11 to 81), mean body mass index was 31.63 kg/m(2) (range 17.1 to 65) and mean preoperative stone area was 6.23 cm(2) (range 1 to 14.6). Six and 3 patients had full and partial staghorn calculi, respectively. Access was achieved via the upper pole in 16 patients, middle pole in 7 and lower pole in 7. Mean operative time was 114.8 minutes (range 61 to 237). Mean estimated blood loss was 145.5 cc (range 10 to 500) and mean postoperative hospital stay was 4.89 days (range 2 to 14). A total of 23 patients (76.7%) had no residual calculi on postoperative computerized tomography, 5 (16.7%) had residual fragments 4 mm or less and 2 (6.7%) had residual stone fragments greater than 4 mm. There were no complications related to the NS.

CONCLUSIONS

The NS is safe, easy to use and has potential advantages compared to currently available renal access sheaths.

Novel everting urologic access sheath: decreased axial forces during insertion

BACKGROUND

Advancement of urologic instruments through the genitourinary tract is associated with significant axial forces that likely contribute to patient discomfort, even after injection of a local anesthetic, and may lead to mucosal trauma, postprocedural dysuria and hematuria, and increased susceptibility to infection and strictures. Placing an everting urethral sheath prior to instrumentation may decrease these problems.

MATERIALS AND METHODS

Two 7-cm-long, 5-mm diameter urethral luminal models were created, one with and one without an artificial stricture. We measured the forces generated during advancement of a novel everting access sheath (Cystoglide; Percutaneous Systems, Mountain View, CA) through the models in comparison with a representative cystoscope and a urologic dilator simulating a traditional access sheath.

RESULTS

The mean force generated during advancement of the everting sheath was significantly less than that of both the representative cystoscope (P<0.01) and the traditional access sheath (P<0.01). This held true for the urethral models both with and without an artificial stricture (P<0.01) and with and without lubrication (P<0.01).

CONCLUSIONS

This novel introduction sheath markedly decreased the axial forces applied to an artificial urethral luminal wall. It is possible that the clinical use of this technology will decrease the discomfort and potential complications associated with lower urinary-tract endoscopy.

One-step percutaneous nephrolithotomy sheath versus standard two-step technique

OBJECTIVES

Advances in technique and equipment have allowed urologists to perform percutaneous stone removal with increasing efficacy and decreasing complications. The procedure of choice for large renal calculi is percutaneous nephrolithotomy. At our institution, percutaneous access is achieved by a two-step process using either Amplatz dilators or placement of a high-pressure balloon catheter for tract dilation, followed by advancement of a sheath over the balloon. A novel device, the Pathway Access Sheath (PAS) has been developed that allows for balloon tract dilation and percutaneous access sheath placement in one simple step.

METHODS

Our study population consisted of 21 patients, who were randomized to one of two arms. Of the 21 patients, 10 underwent standard two-step access using a high-pressure balloon catheter and 11 underwent percutaneous nephrolithotomy using the novel PAS. We compared the insertion time, blood loss, and cost between the two techniques.

RESULTS

The average insertion time was shorter in the PAS group (3 minutes) compared with the high-pressure balloon catheter (5 minutes, 42 seconds); a difference that was statistically significant (P <0.01). The estimated blood loss and cost were similar between the two groups. The increased sheath flexibility of the PAS was noted to be an advantage in some patients.

CONCLUSIONS

The results of our study have shown that a novel single-step renal access device is safe and efficacious and results in a shorter insertion time for percutaneous nephrolithotomy. Blood loss was less in the PAS group as well, although the difference was not statistically significant. Additional studies will establish whether this device will provide a new standard of obtaining renal access.

Outcome from percutaneous nephrolithotomy in patients with spinal cord injury, using a single-stage dilator for access

OBJECTIVE

To present our experience of percutaneous nephrolithotomy (PCNL) for treating urolithiasis in patients with spinal cord injury (SCI) using a single-stage dilator for percutaneous access.

PATIENTS AND METHODS

A prospective database of patients with SCI having PCNL using the single-stage dilator was assessed, analysing patient data, stone-free rates, morbidity and the follow-up outcome.

RESULTS

In all, 26 patients had 54 PCNLs on 32 kidneys; 20 had unilateral and six bilateral stone disease; there were many staghorn calculi (24/54). Major complications occurred in three of 54 PCNLs (6%). The complete stone-clearance rate was 87% for PCNL alone, rising to 29 of 32 kidneys (91%) or 24 of 26 patients (92%) with adjuvant procedures. A further three kidneys required no further treatment and were monitored, having residual fragments of < or = 2 mm.

CONCLUSIONS

PCNL has a high success rate and acceptable complication rate compared to extracorporeal shock-wave lithotripsy, and remains a valid first-line treatment option for kidney stones in patients with SCI.

Failed percutaneous balloon dilation for renal access: Incidence and risk factors

OBJECTIVES

To present our experience using balloon dilation and discuss secondary techniques to establish a percutaneous tract when balloon dilation fails. Balloon dilation is a safe and effective method to achieve percutaneous renal access, but it is not uniformly successful. Also, the failure rate and risk factors have not been well documented.

METHODS

We retrospectively reviewed our last 99 consecutive percutaneous renal procedures using a balloon system as our initial dilation modality. In all cases, the urologist achieved needle access. We determined the balloon failure rate, relationship to prior renal surgery and other patient-related factors, and success rate using secondary techniques of tract dilation.

RESULTS

The balloon did not adequately dilate a tract in 17 (17% failure rate) of 99 cases. The risk factors for failure included a history of prior ipsilateral renal surgery (25% failure rate versus 8% without surgery) and subcostal compared with supracostal puncture (18% versus 9% failure rate). The failure rate was not increased when stratified by laterality, stone composition, stone size and location, or history of ipsilateral renal infection. Amplatz dilators were used in 16 refractory cases and were successful in 15. Metal Alken dilators were successfully used in 2 patients.

CONCLUSIONS

The balloon dilation system is commonly used as the primary modality to establish percutaneous renal access. Although safe and effective (83%), the success rate drops dramatically in patients with prior ipsilateral renal surgery. Knowledge and skill with alternative dilation systems, such as Amplatz or metal Alken dilators, are necessary to successfully gain entry into all renal collecting systems.

Percutaneous nephrolithotomy: an update

PURPOSE OF REVIEW

Percutaneous nephrolithotomy has undergone an evolution in technique and in equipment since its introduction in the late 1970s. This evolution continues today and is evidenced by the numerous publications about the technique. This review summarizes some of the important articles over the past year.

RECENT FINDINGS

Although ureteroscopy and shock wave lithotripsy predominate in the treatment of urolithiasis, percutaneous nephrolithotomy continues to play an important role. Percutaneous nephrolithotomy is advantageous as it causes minimal renal injury and maximizes stone clearance, especially in patients with complex stone disease. Although nephrostomy drainage tubes have always been placed after percutaneous nephrolithotomy, there may be specific indications for tubeless percutaneous nephrolithotomy.

SUMMARY

Percutaneous nephrolithotomy continues to be an important part of the urologist's armamentarium. Recent studies have redefined the role of percutaneous nephrolithotomy and future studies will further delineate the importance of this procedure in the treatment of urolithiasis.