Fluoroscopy-guided Renal Access in Supine Percutaneous Nephrolithotomy

Renal Access in Pediatric Supine Miniaturized Percutaneous Nephrolithotomy: Comparative Evaluation of Ultrasound-Fluoroscopy Combined and Biplanar (0°-90°) Fluoroscopic Techniques

Introduction: Ultrasound (US)-guided puncture has the benefits of avoiding radiation and limiting the risk of visceral injury. We aimed to evaluate the results of two different renal access techniques during pediatric supine mini percutaneous nephrolithotomy (smPCNL) in a comparative manner. Patients and Methods: Data obtained from pediatric patients undergoing smPCNL by single surgeon between September 2021 and 2023 were reviewed retrospectively. Children were divided into two groups namely; biplanar 0°-90° fluoroscopy (Group-F) and US-fluoroscopy combined (Group-C). In all cases, preoperative, operative, and postoperative findings were recorded. Success was defined as the determination of either no (complete stone-free status) or < 4 mm residual fragments (CIRF) on US and X-ray (postoperative 3rd month) images. Complications were evaluated according to modified Clavien-Dindo classification. Results: Data of 54 patients with a mean age of 8.6 years (Group-F = 30, Group-C = 24) are reviewed. In addition to the similar success rates in both groups (Group-F = 86.7% Group-C = 87.5% p = 0.928), similar minor complications were noted in the majority of the cases. No child required transfusion and/or angioembolization. Although the fluoroscopy and operation time were lower in Group-C, the difference was not statistically significant. Conclusion: US-fluoroscopy combined access technique can be applied with similar success and complication rates in pediatric smPCNL. Ultimately, as experience is gained, this technique may lower radiation exposure, although this was not observed in the current study.

Integration and evaluation of a gradient-based needle navigation system for percutaneous MR-guided interventions

The purpose of the present study was to integrate an interactive gradient-based needle navigation system and to evaluate the feasibility and accuracy of the system for real-time MR guided needle puncture in a multi-ring phantom and in vivo in a porcine model. The gradient-based navigation system was implemented in a 1.5T MRI. An interactive multi-slice real-time sequence was modified to provide the excitation gradients used by two sets of three orthogonal pick-up coils integrated into a needle holder. Position and orientation of the needle holder were determined and the trajectory was superimposed on pre-acquired MR images. A gel phantom with embedded ring targets was used to evaluate accuracy using 3D distance from needle tip to target. Six punctures were performed in animals to evaluate feasibility, time, overall error (target to needle tip) and system error (needle tip to the guidance needle trajectory) in vivo. In the phantom experiments, the overall error was 6.2±2.9 mm (mean±SD) and 4.4±1.3 mm, respectively. In the porcine model, the setup time ranged from 176 to 204 seconds, the average needle insertion time was 96.3±40.5 seconds (min: 42 seconds; max: 154 seconds). The overall error and the system error was 8.8±7.8 mm (min: 0.8 mm; max: 20.0 mm) and 3.3±1.4 mm (min: 1.8 mm; max: 5.2 mm), respectively.

Description of a novel method for renal puncture in supine percutaneous nephrolithotomy and comparison with a previously described method

OBJECTIVE

The supine position is becoming increasingly popular in percutaneous nephrolithotomy (PNL). Renal puncture is the key step for a successful PNL procedure. The aim of this study was to describe a novel method for renal puncture and compare it with a previously described method.

MATERIAL AND METHODS

Data of 358 patients who underwent PNL in the supine position were collected prospectively. In 165 patients, the puncture was performed by a previously described method (Group 1), and in 193 patients, the puncture was performed with the novel method (Group 2). Groups were compared with regard to total time and fluoroscopy time to successful puncture. In the novel puncture technique, the needle is advanced toward the targeted calyx under monoplane fluoroscopy. To determine the needle depth, the C-arm is rotated by 10°. If the needle projection is beyond the targeted calyx in fluoroscopy, the puncture is deeper than desired. If the needle projection does not reach the targeted calyx, the puncture is more superficial than desired.

RESULTS

Groups were similar with regard to the mean age, gender distribution, body mass index, stone size, and site of puncture. The mean total time to puncture was 88.2±25.3 seconds in Group 1 and 54.3±22.3 seconds in Group 2, and the difference was statistically significant (p=0.03). The mean fluoroscopy time to puncture was 16.1±5.3 seconds in Group 1 and 9.3±3.4 seconds in Group 2, and the difference was statistically significant (p=0.03).

CONCLUSION

This novel method to determine the depth of the needle is simple, reproducible, and has the potential to diminish radiation exposure with the aid of intermittent fluoroscopy.

Ultrasound guidance can be used safely for renal tract dilatation during percutaneous nephrolithotomy

OBJECTIVES

To compare clinical outcomes in patients who underwent percutaneous nephrolithotomy (PCNL) with renal tract dilatation performed under fluoroscopic guidance vs renal tract dilatation with ultrasound guidance.

PATIENTS AND METHODS

We conducted a prospective observational cohort study, enrolling successive patients undergoing PCNL between July 2015 and March 2018. Included in this retrospective analysis were cases where the renal puncture was successfully obtained with ultrasound guidance. Cases were then grouped according to whether fluoroscopy was used to guide renal tract dilatation or not. All statistical analyses were performed using Stata version 15.1 including univariate (Fisher's exact test, Welch's t-test) and multivariate analyses (binomial logistic regression, ordinal logistic regression, and linear regression).

RESULTS

A total of 176 patients underwent PCNL with successful ultrasonography-guided renal puncture, of whom 38 and 138 underwent renal tract dilatation with fluoroscopic vs ultrasound guidance, respectively. There were no statistically significant differences in patient age, gender, body mass index (BMI), preoperative hydronephrosis, stone burden, procedure laterality, number of dilated tracts, and calyceal puncture location between the two groups. Among ultrasound tract dilatations, a higher proportion of patients were placed in the modified dorsal lithotomy position as opposed to prone, and a significantly shorter operating time was observed. Only modified dorsal lithotomy position remained statistically significant after multivariate regression. There were no statistically significant differences in postoperative stone clearance, complication rate, or intra-operative estimated blood loss. A 5-unit increase in a patient's BMI was associated with 30% greater odds of increasingly severe Clavien-Dindo complications. A 5-mm decrease in the preoperative stone burden was associated with 20% greater odds of stone-free status. No variables predicted estimated blood loss with statistical significance.

CONCLUSIONS

Renal tract dilatation can be safely performed in the absence of fluoroscopic guidance. Compared to using fluoroscopy, the present study demonstrated that ultrasonography-guided dilatations can be safely performed without higher complication or bleeding rates. This can be done using a variety of surgical positions, and future studies centred on improving dilatation techniques could be of impactful clinical value.

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.

Feasibility and Safety of Ultrasonography Guidance and Flank Position during Percutaneous Nephrolithotomy

PURPOSE

Percutaneous nephrolithotomy is generally performed using fluoroscopy, which is associated with exposure to radiation. Another drawback of fluoroscopic guided percutaneous nephrolithotomy is the prone position, which is not suitable for all patients. In this study we evaluated the feasibility, safety and efficacy of ultrasound guided percutaneous nephrolithotomy with the patient in the flank position.

MATERIALS AND METHODS

A total of 603 patients with a mean ± SD age of 50.9 ± 13 years were included in this study from December 2010 to July 2016. Access to the collecting system and tract dilation were performed under ultrasound guidance. Perioperative data on the stone-free rate, operative time, length of stay and complication rates were recorded.

RESULTS

Successful access was achieved in all but 1 patient. Mean operative time was 56.6 ± 6.5 minutes. Complete stone clearance was achieved in 529 patients (87.7%) and Clavien-Dindo grade 3 complications were noted in 17 (2.8%). Blood transfusion was necessary in 43 patients (7.1%). However, bleeding was self-limited in all cases and did not require angioembolization.

CONCLUSIONS

To our knowledge this is the largest series of ultrasound guided percutaneous nephrolithotomy with the patient in the flank position. Unlike in other studies we used this procedure in all patients irrespective of stone burden, renal anomaly and body habitus. Ultrasound guided percutaneous nephrolithotomy has outcomes comparable to those of conventional percutaneous nephrolithotomy and it is not associated with radiation exposure. Furthermore, anesthesia while in the flank position might be less harmful in some patients, including those with obesity or cardiopulmonary comorbidities.

European Section of Urotechnology educational video on fluoroscopic-guided puncture in percutaneous nephrolithotomy: all techniques step by step

OBJECTIVE

To describe the most common fluoroscopic-guided access techniques during percutaneous nephrolithotomy (PCNL) in a step-by-step manner and to assist in the standardisation of their technique and terminology.

METHODS

A high-quality animation video was created for each of the respective fluoroscopic techniques, focusing into the parallel projection of external surgical manoeuvres and their effect in the three-dimensional space of the kidney.

RESULTS

Four predominant fluoroscopic-guided percutaneous access techniques are available, each with different advantages and limitations. Monoplanar access is used when a stable single-axis fluoroscopic generator is available and is mostly based on surgeons' experience. Biplanar access uses a second fluoroscopy axis to assess puncture depth. The 'bull's eye' technique follows a coaxial to fluoroscopy puncture path and is associated with a shorter learning curve at the cost of increased hand radiation exposure. Hybrid and conventional triangulate techniques use target projection by two fluoroscopic planes to define the exact localisation of the target in space and access it through a third puncture site.

CONCLUSIONS

Fluoroscopic guidance during PCNL puncture is a very efficient method for access establishment. The percutaneous surgeon should be familiar with all available variations of fluoroscopic approach in order to be prepared to adapt puncture technique for any given scenario.

Torsional dynamics of steerable needles: modeling and fluoroscopic guidance

Needle insertions underlie a diversity of medical interventions. Steerable needles provide a means by which to enhance existing needle-based interventions and facilitate new ones. Tip-steerable needles follow a curved path and can be steered by twisting the needle base during insertion, but this twisting excites torsional dynamics that introduce a discrepancy between the base and tip twist angles. Here, we model the torsional dynamics of a flexible rod-such as a tip-steerable needle-during subsurface insertion and develop a new controller based on the model. The torsional model incorporates time-varying mode shapes to capture the changing boundary conditions inherent during insertion. Numerical simulations and physical experiments using two distinct setups-stereo camera feedback in semitransparent artificial tissue and feedback control with real-time X-ray imaging in optically opaque artificial tissue-demonstrate the need to account for torsional dynamics in control of the needle tip.

Prone versus supine lasix renal scan to assess surgical success after laparoscopic and robot-assisted pyeloplasty

PURPOSE

Success after laparoscopic pyeloplasty (LP) for ureteropelvic junction obstruction is determined based on renal scan (RS) results and patient symptoms ± ultrasonography. The upright or prone position during RS may facilitate drainage. This study reports on outcomes after LP and robot-assisted pyeloplasty (RALP) and determines if patient position (supine vs prone) alters the results of the postoperative RS and surgical "success."

PATIENTS AND METHODS

A retrospective review of LP and RALP performed by one surgeon between 2005 and 2012 was performed. Follow-up consisted of RS ± ultrasonography. The paired t test was used to assess for a significant difference between mean T1/2 for supine vs prone scans in each patient. Linear regression was used to determine if preoperative split renal function on the affected side or degree of preoperative hydronephrosis predicted difference in supine vs prone T1/2.

RESULTS

There were 11 LP and 81 RALP performed; 84 had follow-up data. There were four (4.3%) failures. Thirty-eight patients had sufficient supine and prone RS for analysis. The difference in T1/2 between supine and prone RS was significant (mean difference 10.18 ± 27.28 min, P = 0.03). Strict success increased to 65.8% from 44.7% and combined strict plus technical success increased to 78.9% from 63.1% on prone vs supine RS. Split function and degree of hydronephrosis were not predictors of difference in RS results.

CONCLUSIONS

LP and RALP have good technical results. Prone position for RS may facilitate drainage and may be a more accurate representation of postoperative outcome after pyeloplasty, particularly in equivocal cases.

The ideal puncture approach for PCNL: Fluoroscopy, ultrasound or endoscopy?

Percutaneous renal access is a common procedure in urologic practice. The main indications are drainage of an obstructed and hydronephrotic kidney and antegrade renal access prior to percutaneous renal surgeries such as percutaneous nephrolithotomy (PCNL) and percutaneous endopyelotomy (EP). The contraindications for this technique are patients with history of allergy to topical or local anesthesia and patients with coagulopathy. The creation of a percutaneous tract into the renal collecting system is one of the important steps for percutaneous renal access. This step usually requires imaging. The advantages and disadvantages of each modality of image guidance are controversial. We performed a structured review using the terms: Percutaneous nephrostomy, guidance, fluoroscopy, ultrasonography, computed tomography (CT) scan, and magnetic resonance imaging (MRI). The outcomes are discussed.

Antegrade percutaneous flexible endoscopic approach for the management of urinary diversion-associated complications

PURPOSE

We present our experience in the minimally invasive management of postoperative complications associated with urinary diversions using an ureteral access sheath (UAS) in an antegrade approach.

PATIENTS AND METHODS

From 2005 to 2011, 21 antegrade flexible ureteroscopies (F-URS) were performed in 17 patients with a urinary diversion. Urinary diversions in this population consisted of ileal conduits, orthotopic neobladders, catheterizable pouches, and an ureterosigmoidostomy in 9, 5, 2, and 1 patients, respectively. The most important reason for treatment was recurrent upper urinary tract infection. The indication for intervention was stone disease in 15 procedures and strictures in 6 cases. In two patients, "staged-therapy" was performed. Using UAS in an antegrade approach was the main concept.

RESULTS

A nephrostomy tube was already in place in 14 (66.6%) procedures, which was the access route used. Successful puncture was performed in all other patients. Eighty percent of patients were rendered stone free after the first antegrade session. Moreover, all strictures were successfully managed by dilation. In two sequential procedures in a patient, there was an inability to perform stone treatment because of abnormal position of the ureter (kinked), which did not allow the ureterorenoscope to pass. All other procedures were uneventful. Postoperative complications were reported in four procedures. There was significant urinary tract infection in two patients as well as an obstructed nephrostomy tube in two patients.

CONCLUSION

An antegrade endoscopic procedure using UAS in patients who present with stones or ureterointestinal stricture as late complications of urinary diversion is a feasible, well-tolerated technique, especially when using smaller access sheaths.