Percutaneous Nephrolithotomy Access: A Systematic Review of Intraoperative Assistive Technologies

Learning curve of ultrasound-guided percutaneous nephrolithotripsy in the treatment of complex renal calculi

OBJECTIVE

This study was performed to investigate the learning curve of ultrasound-guided percutaneous nephrolithotripsy (PCNL) for the treatment of complex renal calculi.

METHODS

Seventy-two patients with complex renal stones who underwent ultrasound-guided PCNL by the same operator from November 2016 to September 2020 were retrospectively analyzed. The learning curve of PCNL for complex renal stones was analyzed using multifactorial cumulative sum (CUSUM) analysis and best-fit curves.

RESULTS

The CUSUM best-fit curve peaked at Case 36, which represented the minimum number of cumulative cases required to cross the learning curve for this surgical procedure. Accordingly, the learning curve was divided into a learning improvement period (36 cases) and a proficiency phase (36 cases). Compared with the learning improvement period, the proficiency phase was characterized by a shorter puncture time and operation time, a smaller drop in the hemoglobin level, and a lower postoperative complication rate.

CONCLUSION

The learning curve of PCNL for the treatment of complex renal calculi can be divided into a learning improvement period and a proficiency phase, and the minimum cumulative number of cases is 36.

Comparison of Percutaneous Renal Access Between Robot-Assisted Fluoroscopy Guidance Using the Bi-Plane Method and Ultrasound Guidance: A Multicenter Randomized Control Benchtop Study

Purpose: To evaluate the efficacy of supine percutaneous renal access by robot-assisted (RA) fluoroscopy and ultrasound (US) guidance in terms of procedural outcomes and surgeon workload. Methods: We conducted a multicenter, randomized, controlled benchtop study involving 32 urologists using a renal phantom model. RA puncture was performed using the developed version of automated needle targeting with X-ray (ANT-X), which determines the direction of the needle. US puncture was performed under US guidance. The primary endpoint was the single-puncture success rate, and the secondary outcomes were the procedural time for each step, time of fluoroscopic exposure, and workload assessment. Results: The single-puncture success rates were 90.6% and 56.3% for RA and US punctures, respectively (p < 0.01). In RA puncture, the median device setup time was 120 seconds longer, the median total procedural time was 100 seconds longer, the median time of fluoroscopic exposure was 40 seconds longer, the median needle puncture time was 17 seconds shorter, and the distance from the target sphere was 1 cm shorter than those in US puncture (all p < 0.01). The mental and physical task workload, effort required by the surgeons, frustration felt by the surgeons, and overall National Aeronautics and Space Administration Task Load Index scores were lower in the RA puncture group than in the US puncture group (p = 0.01, p = 0.046, p < 0.01, p = 0.021, and p ≤ 0.01, respectively). Conclusions: RA puncture using ANT-X, which can also be used for puncture in the supine position, offers advantages over renal puncture in terms of accuracy and surgical workload.

A novel less-traumatic needle for kidney puncture: first clinical experience

INTRODUCTION

To decrease complication rate, we developed a novel MG needle for kidney puncture consisting of a pointed cannula, an atraumatic mandrin-bulb and a spring mechanism pushing the mandrin-bulb forward.

AIM OF THE STUDY

To assess efficacy and safety of kidney puncture during percutaneous nephrolithotomy (PCNL) using a novel less-traumatic MG needle within a clinical trial.

MATERIALS AND METHODS

We conducted a prospective randomized single-center study. In the experimental group, kidney puncture was performed with a novel MG needle while in the control group, standard Trocar or Chiba puncture needles were used.

PRIMARY ENDPOINT

hemoglobin drop.

RESULTS

A total of 67 patients were enrolled. Patients who underwent standard puncture (n = 33) had higher hemoglobin drop in the early postoperative period (p = 0.024). Although there was no statistical difference in overall complication rate between the two groups (p = 0.351), two severe Clavien-Dindo IIIa complications with urinoma occurred in patients from the control group.

CONCLUSION

Less-traumatic needle for kidney puncture may reduce hemoglobin drop and prevent the development of severe complications. At the same time, in terms of stone-free rate (SFR), the efficacy of PCNL remains the same regardless of the needle used for renal access.

Percutaneous nephrolithotomy - the puncture

OBJECTIVE

To determine what importance is given to the puncture and assistive technologies in percutaneous nephrolithotomy (PNL) in the current urological literature.

METHODS

PubMed was searched for English publications and reviews for the keywords: 'percutaneous nephrolithotomy', 'percutaneous nephrostomy', 'puncture'. The search was limited to the last 5 years, January 2016 until February 2021. Based on 183 abstracts, 121 publications were selected, read, and reviewed. References, older or seminal papers were read and cited if they contributed to a better understanding. A total of 198 references form the basis of this narrative review.

RESULTS

The puncture is frequently referred to as the most crucial part of PNL. In contrast, the influence of the puncture on the failure rate of PNL and the specific puncture-related complications seems to be low in the single-digit percentage range. However, there are no universally accepted definitions and standards measuring the quality of puncture. Consequently, the impact of the puncture on general PNL complications, on stone scores predicting success rates and on learning curves evaluating surgeons' performance have not been systematically studied. Assistive technologies rely on fluoroscopy and ultrasonography, the latter of which is becoming the preferred imaging modality for monitoring the entire procedure. Needle bending, a problem relevant to all puncture techniques, is not addressed in the urological literature.

CONCLUSIONS

The importance attached to puncture in PNL in the current urological literature is subjectively high but objectively low. Some basics of puncture are not well understood in urology. Disciplines other than urology are more actively involved in the development of puncture techniques.

Surgical Trends in Nephrolithiasis: Increasing De Novo Renal Access by Urologists for Percutaneous Nephrolithotomy

Purpose: Percutaneous nephrolithotomy (PCNL) has wide variability in the methods of renal access. In many centers, this is done as a separate nephrostomy procedure by interventional radiology, while other urologists gain initial access themselves during the PCNL. We aimed to characterize these trends to confirm the need for continued training in this aspect of PCNL. Methods: Using MarketScan insurance claims, we examined surgical volume for ureteroscopy (URS), extracorporeal shockwave lithotripsy (SWL), and PCNL during 2007-2017. For PCNL, current procedural terminology (CPT) codes were used to identify the provider performing the de novo renal access over time. We stratified postoperative outcomes for PCNL by provider type. Results: From 2007 to 2017, the annual proportion of PCNL procedures peaked at 4.5%, with a recent decline in 2016 and 2017 to 3.2%. URS steadily increased from 46.3% to 60.0% of procedures, and SWL mirrored that change with a decrease from 50.0% to 36.7%. Within 19,743 PCNLs, there was a notable increase from 12.8% to 32.3% in the number of procedures with urologists performing de novo renal access. Most cases (40.0%) still had a de novo access code assigned to a radiologist. Length-of-stay, readmission, transfusion, and secondary stone procedure rates were higher in the radiologist-gained access PCNLs. Conclusions: URS has surpassed SWL as the most common stone procedure. While the proportion of PCNLs has remained fairly stable over the last decade, urologists obtaining their own de novo access have increased substantially. Continued outreach efforts focused on urologist-obtained access may further increase this proportion and improve outcomes for PCNL.

Day-surgery percutaneous nephrolithotomy: a high-volume center retrospective experience

PURPOSE

Percutaneous nephrolithotomy (PCNL) is traditionally performed on an inpatient basis. We determine the safety and outcome of day-surgery PCNL by experienced surgeon hands.

PATIENTS AND METHODS

A protocol for day-surgery PCNL was undertaken. A retrospective analysis of all 86 cases of planned day-surgery PCNL accomplished by an experienced surgeon who followed this protocol between May 2017 and March 2019 was performed. Patient demographics, operative data, complications, and readmission rates were recorded. Day-surgery PCNL was defined as discharge of patients either the same day or within 24 h after surgery.

RESULTS

The average stone burden was 361.1 mm² and 70 (81.4%) of patients had multiple stones or staghorn stones. 82 (95.4%) patients achieved same-day discharge or received overnight observation prior to discharge, and 4 patients (4.6%) required full admission (longer than 24 h). The readmission rate was 2.3% (2 patients). The postoperative complications occurred in 10 (11.6%) patients, including 7, 2, 2 of grade I, II, III complications. The average operation time was 64 min and the hemoglobin drop was 15.7 ± 16.9 g/L. The established tracts size ranged from 16 to 22Fr. The stone clearance rate was 90.7%. The tubeless without nephrostomy tube was performed in 60.5%. Eight cases were performed by multiple-tracts PCNL with 2-4 tracts, with only two case required full admission.

CONCLUSION

Experienced surgeons who performed day-surgery PCNL experience excellent patient outcomes in appropriately selected patients. Most complications can be treated conservatively and only a few required intervention or readmission.

Techniques for fluoroscopy-guided percutaneous renal access: An analytical review

Percutaneous renal access is a key step for a successful percutaneous nephrolithotomy. It involves the use of fluoroscopy, ultrasonography, or a combination of both. Over the years, various techniques have been proposed for fluoroscopy-guided access, and this article reviews the different techniques along with the anatomical principles for fluoroscopy-guided percutaneous renal access. A literature search was performed using "PubMed" for relevant literature describing the various techniques for fluoroscopy-guided percutaneous renal access. Each technique was analyzed in regard to how it describes selecting the skin site for puncture and determines the angle and depth of puncture. The advantages, limitations, and variations of these techniques were also studied. Each technique has its advantages and limitations. No study has compared all the techniques either in vivo or in vitro. Only a comparative study would establish the superiority of one technique over the other. Until this is done, endourologists should be well versed with the existing techniques.