Role of Intrarenal Pressure in Modern Day Endourology (Mini-PCNL and Flexible URS): a Systematic Review of Literature

European Association of Urology Guidelines on the Diagnosis and Treatment of Urolithiasis

BACKGROUND AND OBJECTIVE

The European Association of Urology urolithiasis guidelines provide evidence-based recommendations for the diagnosis and treatment of urinary stone disease. Given the complexity and variability of stone formation, individualised patient management is emphasised.

METHODS

The guidelines incorporate evidence from the latest research and focus on risk assessment, imaging techniques, pharmacological management, and surgical interventions. A research librarian conducted literature searches for urolithiasis in the Cochrane Library, Medline, and Embase databases via Dialog-Datastar. The strength of recommendations is also rated.

KEY FINDINGS AND LIMITATIONS

Diagnosis relies on a combination of clinical history, biochemical evaluation, and imaging, with ultrasound as the first-line modality and low-dose computed tomography as the gold standard for precise stone assessment. Stone composition and burden influence treatment decisions with algorithms primarily based on stone size, location, and composition. Nonsteroidal anti-inflammatory drugs are recommended for first-line pain management, with opioids reserved as a secondary option. Medical expulsive therapy with α-blockers may be considered for selected patients with ureteral stones. Extracorporeal shockwave lithotripsy, ureteroscopy, and percutaneous nephrolithotomy remain the primary intervention modalities, with selection based on stone characteristics and patient factors. Advances in multiplanar imaging have improved assessment of the stone burden, although further research is needed to refine predictive models. Genetic testing is recommended for high-risk patients to guide personalised treatment.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The guidelines provide a framework for clinical decision-making while acknowledging the need for continued advances in urolithiasis.

Relocation of big stone fragments with direct-in scope suction

PURPOSE

To investigate the effectiveness of DISS feature of novel 7.5Fr and 9.2Fr single-use flexible digital ureteroscopes to relocate and evacuate stone fragments (2-5 mm in diameter) without any accessory instruments.

METHODS

An ex-vivo experimental study on porcine kidney and ureter was performed. Natural calcium oxalate dihydrate stone fragments sized 2-5 mm placed in the upper, middle and lower calyces were used. For each stone in each location 5 attempts were performed. The attempt was defined as successful if stone evacuation was reported while withdrawing the scope through the 12/14Fr UAS. The time collapsing the collecting system was also reported.

RESULTS

The time needed to collapse the porcine pelvi-calyceal system (PCS) was 4-5 s for 9.2Fr and 5-6 s for 7.5Fr scope. Evacuation of 2 mm stone fragments occurred in all trials both with 9.2Fr and 7.5Fr scopes. In case of 3 mm stone, evacuation of stone fragments was observed in 3 out of 5 and 1 out of 5 attempts in upper calyx, 5 out of 5 and 3 out of 5 in the middle calyx and 2 out of 5 and 0 out 5 in lower calyx using 7.5Fr and 9.2Fr scope, respectively.

CONCLUSION

The DISS feature of the novel 7.5Fr and 9.2Fr single-use digital flexible ureteroscope can be potentially used not only to aspirate dust but also to relocate and evacuate larger stone fragments up to 4 mm in diameter using only suction. The speed of collapse of the PCS seems to be one of the main predictors of success.

Technological innovation and revolution with single-use digital flexible ureteroscopes: a review from section of EAU Endourology

PURPOSE OF REVIEW

Numerous scope-related innovations have taken place in the field of endourology. The presented analytical review is aimed at studying the technical innovations of the single-use digital flexible ureteroscopes. In November 2024, a comprehensive search was done for information on latest disposable flexible digital ureteroscopes, as well as their various unique characteristics. A thorough examination was conducted for image qualities; sizes and channels; and deflection capabilities. Furthermore, supplementary features about the latest advances were assigned to a separate group including 'Unique' solutions. Using the last search query, various innovations in flexible ureteroscopy in general were also searched and sorted into appropriate groups.

RECENT FINDINGS

Modern single-use flexible digital ureteroscopes are characterized by advanced technologies for transmitting light and images, miniaturization, as well as by a number of unique solutions that were previously characteristic only of semi-rigid or fiberoptic endoscopes. These include features such as integrated buttons for data recording, self-locking mechanism, separate ports, rotating shaft, direct-in-scope suction, pressure monitoring, enhanced tip control and customizable settings.

SUMMARY

Since their introduction in urology, endoscopes have undergone many changes, as illustrated by the example of single-use flexible digital ureteroscopes. The imaging quality has improved, the dimensions of both the distal tip and shaft have decreased, with over 15 manufactures producing and distributing these scopes. A lot of new additional new features are likely to enhance the efficacy and safety of ureteroscopic procedures.

International Alliance of Urolithiasis (IAU) consensus on miniaturized percutaneous nephrolithotomy

Over the past three decades, there has been increasing interest in miniaturized percutaneous nephrolithotomy (mPCNL) techniques featuring smaller tracts as they offer potential solutions to mitigate complications associated with standard PCNL (sPCNL). However, despite this growing acceptance and recognition of its benefits, unresolved controversies and acknowledged limitations continue to impede widespread adoption due to a lack of consensus on optimal perioperative management strategies and procedural tips and tricks. In response to these challenges, an international panel comprising experts from the International Alliance of Urolithiasis (IAU) took on the task of compiling an expert consensus document on mPCNL procedures aimed at providing urologists with a comprehensive clinical framework for practice. This endeavor involved conducting a systematic literature review to identify research gaps (RGs), which formed the foundation for developing a structured questionnaire survey. Subsequently, a two-round modified Delphi survey was implemented, culminating in a group meeting to generate final evidence-based comments. All 64 experts completed the second-round survey, resulting in a response rate of 100.0%. Fifty-eight key questions were raised focusing on mPCNLs within 4 main domains, including general information (13 questions), preoperative work-up (13 questions), procedural tips and tricks (19 questions), and postoperative evaluation and follow-up (13 questions). Additionally, 9 questions evaluated the experts' experience with PCNLs. Consensus was reached on 30 questions after the second-round survey, while professional statements for the remaining 28 key questions were provided after discussion in an online panel meeting. mPCNL, characterized by a tract smaller than 18 Fr and an innovative lithotripsy technique, has firmly established itself as a viable and effective approach for managing upper urinary tract stones in both adults and pediatrics. It offers several advantages over sPCNL including reduced bleeding, fewer requirements for nephrostomy tubes, decreased pain, and shorter hospital stays. The series of detailed techniques presented here serve as a comprehensive guide for urologists, aiming to improve their procedural understanding and optimize patient outcomes.

The Evaluation of Intrarenal Pressure Using a Novel Single-Use Flexible Ureteroscope with Live Intrarenal Pressure Monitoring-An Experimental Study in Porcine Models

(1) Background: This study aims to evaluate how different irrigation settings and the use of ureteral access sheaths (UASs) of varying sizes impact intrarenal pressure (IRP) during flexible ureteroscopy (fURS) procedures in pigs. (2) Methods: This study utilized three anesthetized female pigs. A novel flexible ureteroscope with the ability to continuously record live intrarenal pressure was used to perform ureteroscopy in different settings. Ureteroscopy was performed without UAS and with the use of 11/13 and 12/14 UAS at the ureteropelvic junction. Two different irrigation methods were employed for each parameter: one using gravity flow and the other using manual pumping with a commercial pump. IRP was also recorded with the presence of a laser fiber or lithotripsy basket. (3) Results: The recorded mean IRP during flexible URS without UAS was 28.25 (±11.2) under gravity irrigation; 35.46 (±10.08) under manual pumping; 22.5 (±3.05) and 30.75 (±5.79) with a laser fiber under gravity irrigation and manual pumping, respectively; and 16.45 (±1.27) and 17.27 (±3.69) with a lithotripsy basket under gravity irrigation and manual pumping, respectively. With an 11/13 UAS, the mean IRP was 15.41 (±8.57) and 19.33 (±4.26) under gravity and manual pumping irrigation, respectively; 14.56 (±2.50) and 18.64 (±5.13) with a laser in each irrigation setting, respectively; and 13.10 (±3.39) and 13.86 (±4.63) with a lithotripsy basket, respectively. With a 12/14 UAS, the mean IRP was 7.64 (±3.08) and 9.25 (±1.42) under gravity and manual pumping irrigation, respectively; 9.50 (±6.04) and 10.28 (3.46), respectively, in each setting when the laser fiber was used; and 5.32 (±1.57) and 6.26 (±1.79), respectively, when the lithotripsy basket was inserted. (4) Conclusion: Novel flexible ureteroscopes with integrated pressure sensors are both a feasible and reliable tool during fURS, giving the surgeon the ability to live-track the IRP. The results of the IRP measurements with and without UAS are in accordance with the current literature and exhibit a consistent pattern with previous studies.

Needle-perc-assisted endoscopic surgery versus retrograde intrarenal surgery for the treatment of 1- to 2-cm lower-pole renal stones in patients with unfavorable infundibulopelvic anatomy: a matched-pair analysis

PURPOSE

To compare the safety and efficacy of needle-perc-assisted endoscopic surgery (NAES) and retrograde intrarenal surgery (RIRS) for the treatment of 1- to 2-cm lower-pole stones (LPS) in patients with complex infundibulopelvic anatomy.

METHODS

Between June 2020 and July 2022, 32 patients with 1- to 2-cm LPS and unfavorable lower-pole anatomy for flexible ureteroscopy were treated with NAES. The outcomes of these patients were compared with patients who underwent RIRS using matched-pair analysis (1:1 scenario). The matching parameters such as age, gender, body mass index, stone size, hardness, and pelvicalyceal anatomy characteristics including infundibular pelvic angle, infundibular length, and width were recorded. Data were analyzed using the Student's t-test, Mann-Whitney U test, and Fisher's exact test.

RESULTS

The two groups had similar baseline characteristics and lower-pole anatomy. The stone burden was comparable between both groups. NASE achieved a significantly better initial stone-free rate (SFR) than RIRS (87.5% vs 62.5%, p = 0.04). The auxiliary rates for the NAES and RIRS groups were 12.5% and 31.3%, respectively (p = 0.13). Finally, the SFR after 1 month follow-up period was still higher for the NAES group than RIRS group (93.8% versus 81.3%), but the difference was not statistically significant (p = 0.26). Concerning the operation duration, overall complication rates, and postoperative hospital stay, there were no differences between two groups.

CONCLUSION

Compared to RIRS for treating 1- to 2-cm LPS in patients with unfavorable infundibulopelvic anatomy for flexible ureteroscopy, NAES was safe and effective with higher SFR and similar complication rate.

Scoping Review of Experimental and Clinical Evidence and Its Influence on Development of the Suction Ureteral Access Sheath

The ureteral access sheath (UAS) has been a boon and a bane in flexible ureteroscopy (FURS), with its merits and demerits well established. Its design and dimensions were instrumental in reshaping the way flexible scopes were used and were key adjuncts to establishing retrograde intrarenal surgery (RIRS) as a standard of care in the endourological management of renal stones. With the ever-changing landscape of RIRS over the decades shaped by technological advancements in lasers and flexible scopes, the UAS has also continuously evolved. The utility of suction in endourology has recently changed the way RIRS is performed and is a game changer for FURS outcomes. With strong clinical and experimental evidence to support its use, the UAS has undergone a transformative change in the recent past, with its ability to monitor intrarenal pressure and provide a superior vacuum-cleaner effect that improves the trifecta of RIRS, namely an improved single-stage stone-free rate (SFR), minimise complications, and reduce reinterventions. Our comprehensive review outlines the key clinical and experimental evidence and traces the developments that were key to modifying the traditional UAS into a flexible and navigable suction ureteric access sheath (FANS) and highlights how the design and modifications, in turn, influence the ability to push the boundaries of RIRS.

Factors affecting the intraoperative calculi excretion during flexible ureteroscopy lithotripsy: an in vitro analysis

OBJECTIVE

To explore the parameters influencing intraoperative calculi excretion (ICE) during flexible ureteroscopy lithotripsy (fURL) using in vitro simulation experiments.

METHODS

3D-printed human kidney models were used to simulate the elimination of gravel during fURL. The factors influencing the ICE during fURL were analyzed by comparing the effects of different degrees of hydronephrosis (mild, moderate, and severe), surgical positions (supine and lateral position), ratios of endoscope-sheath diameter (RESD) (0.625, 0.725, and 0.825), gravel sizes (0.50-1.00 mm, 0.25-0.50 mm, and 0.10-0.25 mm), and ureteral access sheaths (UASs) (traditional UAS and negative-pressure UAS) on ICE.

RESULTS

The impacts of various UAS, RESD, degree of hydronephrosis, surgical positions, and gravel sizes on ICE were all significant (p < 0.05). We found no evidence of multicollinearity for all the independent variables, and the linear regression equation fitted as ICE ( g / min ) = 0.102 + 0.083 ∗ UAS grade - 0.050 ∗ RESD grade - 0.048 ∗ hydronephrosis grade + 0.065 ∗ position grade - 0.027 ∗ gravel size grade (R2 = 0.569).

CONCLUSION

Employing negative-pressure UAS, smaller RESD, milder hydronephrosis, lateral position, and smaller gravel size contribute to improved ICE during fURL. Among them, the adoption of negative-pressure UAS had the most substantial effects.

Retrograde intrarenal surgery with intelligent control of renal pelvic pressure for staghorn calculi: a case report

Percutaneous nephrolithotomy is the gold standard treatment for staghorn calculi. However, this study reviews a case of an almost complete removal of staghorn calculi following one session of retrograde intrarenal surgery with intelligent control of renal pelvic pressure (RIRS-ICP). A 45 years-old female patient with an 8.3 × 4.5 cm complete staghorn stone was infected with Proteus mirabilis. Two sensitive antibiotics, piperacillin tazobactam and etimicin, were administered for 3 days. Semirigid 7/8.4 Fr ureteroscope was used to treat the renal pelvis and upper calyceal calculi for 57 min. A 550 μm holmium laser fiber with 2.0 J × 30 Hz was set. Next, a disposable flexible ureteroscope of 8.4 Fr was used to address residual middle and lower calyx stones for 94 min. A 200 μm holmium laser fiber with 1.0 J × 30 Hz was set. The renal pelvis pressure was controlled within 15 mmHg. A 2 mm CT scan on the first postoperative day showed inferior caliceal residue of approximately 1.0 × 0.6 cm. No complications occurred. This suggests that RIRS-ICP is a safe and effective treatment for staghorn calculi.

Suction in Percutaneous Nephrolithotripsy: Evolution, Development, and Outcomes from Experimental and Clinical studies. Results from a Systematic Review

CONTEXT

Controversy exists regarding the therapeutic benefit of suction use during percutaneous nephrolithotripsy (PCNL).

OBJECTIVE

To review and highlight the options available in the use of suction for PCNL, and to discuss their strengths and limitations.

EVIDENCE ACQUISITION

A systematic literature search was performed using Scopus, EMBASE, and PubMed. Thirty four studies were included. There was one ex vivo study. Among clinical studies, 24 used a vacuum/suctioning sheath and nine a handpiece suction device/direct-in-scope suction. The suction technique was employed in standard, mini-PCNL, supermini-PCNL, and enhanced supermini‑PCNL techniques.

EVIDENCE SYNTHESIS

Handpiece suction devices demonstrated better safety and efficiency in treating large stones than nonsuction PCNL and in a much shorter time. Trilogy and ShockPulse-SE were equally effective, safe, and versatile for standard PCNL and mini-PCNL. The heavier handpiece makes Trilogy less ergonomically friendly. Laser suction handpiece devices can potentiate laser lithotripsy by allowing for better laser control with simultaneous suction of small fragments and dust. Integrated suction-based sheaths are available in reusable and disposable forms for mini-PCNL only. Mini-PCNL with suction reported superior outcomes for operative time and stone-free rate to mini-PCNL. This also helped minimize infectious complications by a combination of intrarenal pressure reduction and faster aspiration of irrigation fluid reducing the risk of sepsis, enhance intraoperative vision, and improve lithotripsy efficiency, which makes it a very attractive evolution for PCNL.

CONCLUSIONS

Suction devices in PCNL are reforming the way PCNL is being done. Adding suction to mini-PCNL reduces infectious complications and improves the stone-free rate. Our review shows that despite the limited evidence, suction techniques appear to improve PCNL outcomes.

PATIENT SUMMARY

In this review, we looked at the intra- and perioperative outcomes of percutaneous nephrolithotripsy (PCNL) with the addition of suction. With better stone fragmentation and fewer postoperative infections, this technology is very useful particularly for mini-PCNL.

Comparison of traditional and novel tip-flexible suctioning ureteral access sheath combined with flexible ureteroscope to treat unilateral renal calculi

OBJECTIVES

To compare the safety and efficacy of novel tip-flexible suctioning ureteral access sheath (NTFS-UAS) and traditional ureteral access sheath (T-UAS) combined with flexible ureteroscope for treating unilateral renal calculi.

MATERIALS AND METHODS

The clinical data of 214 patients with unilateral renal calculi treated by NTFS-UAS (n = 102) and T-UAS (n = 112) combined with flexible ureteroscope from August 2021 to April 2022 were analyzed retrospectively. Demographic characteristics, stone-related parameters, operative time, stone-free rates (SFR), hospitalization time and complication rate (CR) were analyzed.

RESULT

No significant difference was observed between the two groups in terms of demographic characteristics, stone-related parameters, intraoperative CR, and hospitalization time. The operative time of NTFS-UAS group was significantly shorter than T-UAS group (55.25 ± 11.42 min vs. 59.36 ± 15.59 min; P = 0.028). The NTFS-UAS group obtained significantly higher SFR on 1 day postoperatively (86.3% vs. 75.0%; P = 0.038), and higher SFR on 30 days postoperatively than T-UAS group (91.2% vs. 81.3%; P = 0.037). The hemoglobin loss of NTFS-UAS group (- 0.54 ± 0.69 g/dl) was significantly lower than T-UAS group (- 0.83 ± 0.66 g/dl; P = 0.002). There was a significantly lower incidence of overall CR (11.8% vs. 22.3%; P = 0.041), and infectious CR (8.8% vs. 18.8%; P = 0.037) in the NTFS-UAS group.

CONCLUSION

Compared to T-UAS combined with flexible ureteroscope for treating unilateral renal calculi, NTFS-UAS had superiority in higher SFR on 1 day and 30 days postoperatively. Shorter operation time, lower hemoglobin loss, lower incidences of overall and infectious CR were observed in NTFS-UAS group.

REGISTRATION NUMBER AND DATE

ChiCTR2300070210; April 5, 2023.

2022 Recommendations of the AFU Lithiasis Committee: Ureteroscopy and ureterorenoscopy

Technical advances, including miniaturization, have improved the deflection and optical performance of the ureteroscopes, and the availability of dedicated disposable devices have led to their increasing use for kidney and ureteral stone management. Ureterorenoscopy brings diagnostic evidence through the endoscopic description of stones and renal papillary abnormalities. Currently, intracorporeal lithotripsy during ureterorenoscopy is based on laser sources. Routine ureteral stenting is not necessary before ureterorenoscopy, especially because preoperative stenting for>30 days is considered as an independent risk factor of infection. Ureteral access sheaths allow the easy and repeated access to the upper urinary tract and thus facilitate ureterorenoscopy. Their use improves vision, decreases intrarenal pressure, and possibly reduces the operative time, but they may cause ureteral injury. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether or not the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis [EAU 2022]) and their adaptability to the French context.

A Prospective Study of Renal Blood Flow during Retrograde Intrarenal Surgery

(I) Introduction: The use of Doppler ultrasound allows us to indirectly assess the effect of increased intrarenal pressure on renal blood flow during retrograde intrarenal surgery (RIRS). On the basis of vascular flow spectra from selected blood vessels in the kidney, it is possible to determine Doppler parameters that reflect the renal perfusion status, which indirectly shows the degree of vasoconstriction and reflects the resistance of kidney tissue. (II) Materials and methods: A total of 56 patients were included in the study. The study assessed the changes of three Doppler parameters of intrarenal blood flow: resistive index-RI, pulsatility index-PI, and acceleration time-AT in the ipsilateral and contralateral kidneys during RIRS. The effects of mean stone volume, energy used, and pre-stenting were examined as predictors and calculated at two time intervals. (III) Results: The mean value of RI and PI was significantly higher in the ipsilateral kidney than in the contralateral kidney just after RIRS. The mean value of the acceleration time was not significantly different before and after RIRS. The values of all three parameters 24 h after the procedure were comparable to their values immediately after the RIRS. The size of the stone exposed to laser lithotripsy, the value of the energy used, and pre-stenting are not factors that significantly influence Doppler parameters during RIRS. (IV) Conclusions: The significant increase in RI and PI after RIRS in the ipsilateral kidney suggests a vasoconstriction of the interlobar arteries generated by increased intrarenal pressure during the procedure.

What is the appropriate gravel size during ureteroscopy lithotripsy? An in vitro evaluation

To propose the suitable diameter of calculus debris produced during flexible ureteroscopy lithotripsy (fURL). A glass tube was used to simulate the stone excretion process during Furl. Different stone diameters (0.50-1.00 mm, 0.25-0.50 mm, and 0.10-0.25 mm) with three sizes of flexible ureteroscopy (fURS) (7.5Fr, 8.7Fr, and 9.9Fr) and ureteral access sheath (UAS) (12/14Fr) with or without negative pressure suction were employed in the experiment. The intraoperative calculi excretion (ICE) was recorded according to the stones discharged from the gap between fURS and UAS. The ICE raised significantly in thinner fURS and UAS due to the smaller Ratio of Endoscope-Sheath Diameter (RESD). The gravel size ≤ 0.25 mm was conducive to drainage with traditional UAS, while using fURS with negative-pressure UAS could significantly improve ICE. The gravel size ≤ 0.5 mm was conducive to expulsion. We clarify that ICE during ureteroscopy relates to RESD and negative pressure suction. The proper size of the stone fragment is critical in ensuring the expulsion during fURL, ≤ 0.25 mm in traditional UAS and ≤ 0.50 mm in negative-pressure UAS, respectively.

Best Practice in Interventional Management of Urolithiasis: An Update from the European Association of Urology Guidelines Panel for Urolithiasis 2022

PURPOSE

The European Association of Urology (EAU) has updated its guidelines on clinical best practice in urolithiasis for 2021. We therefore aimed to present a summary of best clinical practice in surgical intervention for patients with upper tract urolithiasis.

MATERIALS AND METHODS

The panel performed a comprehensive literature review of novel data up to May 2021. The guidelines were updated and a strength rating was given for each recommendation, graded using the modified Grading of Recommendations, Assessment, Development, and Evaluations methodology.

RESULTS

The choice of surgical intervention depends on stone characteristics, patient anatomy, comorbidities, and choice. For shockwave lithotripsy (SWL), the optimal shock frequency is 1.0-1.5 Hz. For ureteroscopy (URS), a postoperative stent is not needed in uncomplicated cases. Flexible URS is an alternative if percutaneous nephrolithotomy (PCNL) or SWL is contraindicated, even for stones >2 cm. For PCNL, prone and supine approaches are equally safe. For uncomplicated PCNL cases, a nephrostomy tube after PCNL is not necessary. Radiation exposure for endourological procedures should follow the as low as reasonably achievable principles.

CONCLUSIONS

This is a summary of the EAU urolithiasis guidelines on best clinical practice in interventional management of urolithiasis. The full guideline is available at https://uroweb.org/guidelines/urolithiasis.

PATIENT SUMMARY

The European Association of Urology has produced guidelines on the best management of kidney stones, which are summarised in this paper. Kidney stone disease is a common condition; computed tomography (CT) is increasingly used to diagnose it. The guidelines aim to decrease radiation exposure to patients by minimising the use of x-rays and CT scans. We detail specific advice around the common operations for kidney stones.

Advances in Ureteroscopy: New technologies and current innovations in the era of Tailored Endourological Stone Treatment (TEST)

Ureteroscopy has undergone many advances in recent decades. As a result, it is able to treat an increasing range of patient groups including special populations such as pregnancy, anomalous kidneys and extremes of age. Such advances include Holmium laser, high-power systems and pulse modulation. Thulium fibre laser is a more recent introduction to clinical practice. Ureteroscopes have also been improved alongside vision and optics. This article provides an up-to-date guide to these topics as well as disposable scopes, pressure control and developments in operating planning and patient aftercare. These advances allow for a custom strategy to be applied to the individual patient in what we describe using a new term: Tailored endourological stone treatment (TEST).

Level of evidence: 5

Intrarenal pressures during percutaneous nephrolithotomy: a porcine kidney model

BACKGROUND

Increased intrarenal pressure during endoscopic lithotripsy is associated with increased adverse outcomes. The objective of this study was to evaluate the effect of various devices on IRP during percutaneous intrarenal surgery in ex vivo porcine kidney models.

METHODS

Whole intact porcine urinary tracts were harvested. Intrarenal pressure was measured using cystometrometry software. Intrarenal pressure during PCNL was recorded using variations of percutaneous access sheath size, irrigation height of 100 cm and 60 cm, use of a ureteric catheter and use of suction. The primary outcome was absolute IRP measurements. Secondary outcomes were comparisons of IRP between techniques.

RESULTS

Using a 30 Fr vs 26 Fr access sheath and 26 Fr nephroscope the mean pressure at an irrigation height of 60 cm was significantly lower than 100 cm (p = 0.0013 vs p < 0.0001, respectively). Pressure's during mini-PCNL were significantly higher than conventional PCNL in all variations. Using the 16.5 Fr access sheath and 12 Fr nephroscope produced a significantly lower pressure at a 60 cm irrigation height than 100 cm (p = 0.0010). IRP was significantly lower with a ureteric catheter in place vs no ureteric catheter at 100 cm (p = 0.0015) and at 60 cm (p = 0.0040).

CONCLUSIONS

Using standard PCNL tract sizes intrarenal pressure varied significantly depending on the height of the irrigation fluid. Mini-PCNL is at higher risk of pathological pressure, however, the use of a ureteric catheter significantly decreased pressure. To maintain safe IRP during PCNL urologists should be aware of these significant variations.