Fluoroscopy guided percutaneous renal access in prone position

Preliminary experience with lost mini percutaneous nephrostomy channel retrieval by methylene blue injection

Percutaneous nephrolithotomy (PCNL) is the primary choice for managing large renal stones and the establishment of mini-/micro-channels has been increasingly gaining practice. The smaller the channel, the easier it is to be lost, which may require a new puncture site and increase the risk of bleeding complications. In this study, we retrospectively reviewed 1,056 PCNL procedures in our single institute, The University of Hong Kong - Shenzhen Hospital, between March 2014 and August 2023. Twenty-three cases of nephrostomy channel loss during mini PCNL were identified, resulting in an incidence rate of 2.2%. Methylene blue was immediately injected into the ureteral catheter to facilitate location and retrieval of the channel. Once extravasation of the dye was identified under rigid ureteroscope, a first guidewire was introduced into the channel for maintenance, followed by another guidewire inserted in parallel to facilitate dilatation. The major reasons for PCNL channel loss were mild hydronephrosis and complete obstruction of the target calyx due to renal stones. Technical success, defined as the ability to retrieve the lost channel within 5 minutes, was 78.3% (n=18/23). Three channels were completely lost and 2 patients showed channel bleeding despite successful identification, all of which required establishment of a new PCNL channel. No major intraoperative nor postoperative complication was observed.

A new model of inexpensive portable homemade PERC Mentor (IPHOM) and its validation

Background

Percutaneous nephrolithotomy (PCNL) is a complex surgery and has a flat learning curve. Due to this and the ethical issues, trainees do not get enough hands on exposure. Virtual simulator is very expensive and bulky. Animal model requires legal clearance. This inexpensive portable homemade PERC Mentor (IPHOM) teaches all the major aspects of PCNL surgery. This article has shown the way to make this model and its validation study.

Methods

IPHOM can be made at home with carton box, ball bearings, LED torch and some hospital wastes. After a short demonstration of IPHOM, 14 residents and 4 urologists were given 8 tasks to perform on it followed by 15-min supervised practice exercise on day 0 and day 1. Their performance was reassessed on day 2 and 3. Response to 17 feedback points was recorded on a seven-point Likert scale.

Results

There was significant difference between the performance of expert and novice on day 0. Expert completed all the tasks in less time and no. of attempts. The time for tract dilatation and duration of radiation exposure were significantly less in the expert group. The performance of both expert and novice improved on day 2 and 3, but the improvement was significantly more in novice. Response to the feedback points showed no difference between expert and novice (p > .05).

Conclusions

We have found that training on IPHOM has improved the concept and skills of PCNL in residents. The simplicity and low cost of the model make it constructible at home.

Interior definition of the calyceal orientation suitable for percutaneous nephrolithotripsy via mobile software

To date, there is no paper on defining the puncture of a kidney from the interior view of the pelvicalyceal system (PCS) to alleviate its performance. The objective of this study is to define the usefulness of the Rubik's Cube method determining calyceal orientation from inside via mobile software for the percutaneous nephrolithotripsy (PCNL). Over September 2019-September 2020, 25 patients with indications for PCNL were enrolled in this single-arm study. All patients underwent computed tomography (CT)-urography. Primary endpoints were the duration of renal cavity puncture, number of attempts and success rate. Complication rate ordered according to Clavien-Dindo classification was analyzed as a secondary endpoint. The stone-free rate was 91%. The same experienced urologist performed all procedures through the single-access PCNL without puncture site reposition. The puncture was made through the upper, middle, and lower calyx in 9, 12 and 4 cases, respectively. The mean duration of cavity puncture was 2.8 ± 1.1 min. The mean number of attempts to reach desirable calyx was 1.4 ± 0.6. It should be noted that there were no cases with three and more punctures. The overall complication rate was 28% (7/25) when only one patient experienced ≥ 3 Grade. The proposed Rubik's Cube method facilitates preoperative planning of PCNL and makes that procedure easier for specialists and safer for the patients.

Air vs contrast pyelogram for initial puncture access in percutaneous nephrolithotomy: a randomized controlled trial

Percutaneous nephrolithotomy (PCNL) is a standard procedure for large renal stones. Contrast (traditionally) as well as air is being used to delineate pelvi-calyceal system (PCS) to perform initial puncture. Contrast, when used has certain disadvantages including poor differentiation of anterior and posterior calyces. In this interim analysis of 122 patients of a prospective study subjects were stratified in two groups: in group 1, contrast was used while in group 2, air was used to delineate PCS. Out of 122,103 patients underwent puncture by contrast or air exclusively while 19 patients required mix of contrast and air (14 patients failed puncture using contrast while 5 using air). Mean dosage of radiation exposure (8.43 vs. 14.26 mGy), duration of radiation exposure (0.66 vs. 1.02 min), access time (3.72 vs. 5.84 min), were less in group 2 as compared to group 1. 84.5% of patients underwent puncture in single attempt in group 2 as compared to 56.25% in group 1. Five patients had post-operative fever and one had trans-pleural tract dilation. Complete stone clearance was seen in 94.8% of patients using air to only 75% of patients using contrast. Conclusion: Air pyelogram is a feasible, safe, cost effective and efficient access alternative to contrast pyelogram and in difficult situation a mixture of both is better than using one.

Trigonometric Concept of Fluoroscopy-Guided Percutaneous Renal Access

Percutaneous nephrolithotomy is the standard surgical management of large renal calculi. Percutaneous renal access using the triangulation method has been an enigma for the endourologist to master and teach. This surgical conundrum is due to the uncertainty in the angle and depth required to puncture the target calyx. We describe a novel trigonometric method of renal access where both the angle and the depth of puncture are easily determined before the puncture.

Critical causes in severe bleeding requiring angioembolization after percutaneous nephrolithotomy

Background

To identify the risk factors for severe bleeding requiring angioembolization among patients who received transfusions after PCNL, particularly those who underwent anatomically incorrect renal puncture.

Methods

A total of 53 patients, who received transfusions after PCNL and simultaneously had a postoperative CT scan performed between November 2009 and May 2019 at two teaching hospitals, were retrospectively reviewed. The patients were divided into two groups: those who underwent angioembolization and those who did not. Patient, stone and procedural factors were compared between the two groups. Puncture correctness was evaluated using postoperative CT scans. Puncture was defined as being a correct puncture if the fornix or papilla of the posterior calyx was punctured and the trajectory of the tract was within 20 degrees posterior to the frontal plane of the kidney (i.e., within Brödel’s line).

Results

21 patients underwent angioembolization after PCNL. Incorrect puncture was seen in 14/21 (66.7%) patients who underwent angioembolization after PCNL, whereas it was seen in 11/32 (34.4%) patients who did not undergo angioembolization (p = 0.021). On multivariable regression analysis, puncture correctness was found to be the only significant factor, with an OR of 3.818, 95% CI of 1.192–12.231 and p value of 0.024.

Conclusions

Incorrect renal puncture was related to severe bleeding requiring angioembolization after PCNL. Our results emphasize the importance of the basic principle of renal puncture for PCNL.

Treatment of Complex Renal Calculi by Digital Flexible Ureterorenoscopy Combined with Single-Tract Super-Mini Percutaneous Nephrolithotomy in Prone Position: A Retrospective Cohort Study

Background

Advances in percutaneous nephrolithotomy (PCNL) have resulted in smaller devices that cause less trauma and bleeding, while flexible ureterorenoscopy (f-URS) allows access to any calyces. These methods are often used in isolation, but used in combination they may improve treatment of complex renal calculi. This study assessed the effectiveness and complications of f-URS combined with super-mini-PCNL (SMP) to treat complex renal calculi.

Material/Methods

A retrospective cohort analysis was made of patients with unilateral complex renal stones treated between March 2013 and December 2016. Patients were grouped according to surgical procedure: SMP (SMP Group), f-URS holmium laser lithotripsy (f-URS Group), and combined SMP and f-URS (Combined Group). The postoperative complications and complete stone-free rate were analyzed and compared among the 3 groups.

Results

A total of 140 patients with complex renal stones were included: 40 patients in the SMP Group, 55 in the f-URS Group, and 45 in the Combined Group. The complete stone-free rate 3 days after the procedure was 77.5% in the SMP Group, 78.2% in the f-URS Group, and 97.8% in the Combined Group (p=0.010). The operation time, intraoperative blood loss, and hospitalization time of the Combined Group were all significantly lower than those in the SMP Group but higher than those in the f-URS Group. The follow-up was 9 months (range, 6–12 months). There were no medium-term complications reported.

Conclusions

SMP combined with f-URS holmium laser lithotripsy in the prone position is an effective treatment for complex renal calculi.

The anatomy of the renal pyelocaliceal system studied by CTU

INTRODUCTION AND OBJECTIVES

Knowledge of the pyelocaliceal system anatomy is essential for the safe and successful performance of endourologic procedures. The purpose of this study was to provide a better understanding of the full three-dimensional pyelocaliceal system anatomy.

METHODS

Morphometric parameters of the three-dimensional reconstructions of computed tomography intravenous urography scans (n = 25 scans) were analyzed. Both kidneys were divided into three equal-sized segments (US: upper segment, MS: mid segment, LS: lower segment). Infundibular length (IL), infundibular width (IW), the number of calyces, and the transverse orientation in hours of a clock of each calyx as well as the dimension of the pyelum were determined.

RESULTS

The mean upper IL (n = 92) was longer than the middle (n = 154) and lower IL (n = 112) (30.6 ± 7.9 mm vs. 16.4 ± 7.7 mm vs. 16.0 ± 6.0 mm, respectively; P = < 0.0001). IW was significantly smaller in the MS [3.7 ± 1.9 mm], followed by the US [4.6 ± 1.9 mm], and the LS [4.9 ± 2.2] in the increasing order. No correlation was found between IL and IW (Pearson correlation coefficient = 0.1). The US calyces were predominantly orientated lateral (8-10 o'clock: 44.5%) and medial (2-4 o'clock: 30.5%), in the MS lateral (8-10 o'clock: 87.6%) and anterolateral in the LS (9-12 o'clock: 67.9%). 74% of the kidneys consisted of 6-8 calyces (mean 7.2 ± 1.4, range 4-10), with the majority of the calyces in the MS (3.1 ± 0.8) followed by the LS (2.24 ± 0.8), and US (1.8 ± 0.7). There were no statistical differences between the right and left kidneys in terms of IL (P = 0.112) and number of calyces (P = 0.685).

CONCLUSION

Anatomic differences between the three segments of the pyelocaliceal system in terms of IL, IW, calyces number, and orientation are seen and should be considered when performing an endourologic procedure.

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.

Present indications and techniques of percutaneous nephrolithotomy: What the future holds?

The purpose of the review was to present the latest updates on percutaneous nephrolithotomy (PCNL) procedure in terms of indications and evolving techniques, and to identify the advantages and disadvantages of each modality. The data for this review were collected after a thorough PubMed search in core clinical journals in English language. The key words included “PCNL” and “PNL” in combination with “indications”, “techniques”, “review” and “miniaturized PCNL”. Publications relevant to the subject were retrieved and critically reviewed. Current European and American Urology Association Nephrolithiasis Guidelines were included as well. The indications for standard PCNL have been changed through the past decade. Despite evolution of the procedure, innovations and the development of new technical approaches, the indications for miniaturized PCNL have not been standardized yet. There is a need for well-constructed randomized trials to explore the indications, complications and results for each evolving approach. A continuous reduction of tract size is not the only revolution of the last years. There is constant ongoing interest in developing new efficient miniature instruments, intracorporeal lithotripters and sophisticated tract creation methods. We can summarize that, PCNL represents a valuable well-known tool in the field of endourology. We should be open minded to future changes in surgical approaches and technological improvements.

X-ray-free Ultrasound-guided Percutaneous Nephrolithotomy: How to Select the Right Patient?

OBJECTIVE

To identify factors associated with successful ultrasound guidance for each surgical step of ultrasound-guided percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

Consecutive patients undergoing PCNL between March 2015 and June 2016 were prospectively enrolled. An attempt was made to use ultrasound guidance in renal access, tract dilation, and nephrostomy tube placement for each patient. For steps during which ultrasound guidance was unsuccessful, fluoroscopic screening was applied. Regression analysis identified patient characteristics associated with successful use of ultrasound guidance.

RESULTS

A total of 96 patients composed this cohort, with a mean body mass index of 28.7 kg/m2. Mean stone size was 33.1 ± 18.9 mm, and no hydronephrosis was found in 63.5% of cases. Fluoroscopic screening was required for renal access in 27 cases (28.1%), tract dilation in 38 (39.6%), and nephrostomy tube placement in 80 (83.3%). Multivariate analysis demonstrated that successful ultrasound guidance was significantly associated with the presence of hydronephrosis for renal access and the absence of staghorn calculi for tract dilation. Ultrasound-guided nephrostomy tube placement appeared linked to surgeon experience.

CONCLUSION

To achieve completely x-ray-free ultrasound-guided PCNL, the ideal patient should have a hydronephrotic collecting system with no staghorn stone present. For practitioners looking to adopt ultrasound guidance into their PCNL practice, these represent the most appropriate patients to safely initiate a surgical experience.

Positioning for percutaneous nephrolithotomy

PURPOSE OF THE REVIEW

To highlight the progressive evolution of the issue of patient positioning for percutaneous nephrolithotomy (PNL), explain the history of the prone and supine positions, report respective advantages and drawbacks, critically interpret the past and current literature supporting such arguments, identify the best candidates for each position, and reflect on the future evolution of the two approaches.

RECENT FINDINGS

Positioning for PNL has become a matter of debate during the last decade. The traditional prone PNL position - most widely performed with good success and few complications, and exhibiting essentially no limits except for the treatment of pelvic kidneys - is nowadays flanked mainly by the supine and supine-modified positions, equally effective and probably safer from an anesthesiological point of view. Of course, both approaches have a number of advantages and drawbacks, accurately reported and critically sieved.

SUMMARY

The current challenge for endourologists is to be able to perform PNL in both prone and supine positions to perfectly tailor the procedure on any patient with any stone burden, including increasingly challenging cases and medically high-risk patients, according to the patient's best interest. Intensive training and experience is especially needed for supine PNL, still less popular and underperformed worldwide.

VIDEO ABSTRACT

http://links.lww.com/COU/A8.