IAU Percutaneous Nephrolithotripsy Study (IAUPCNL)

International Alliance of Urolithiasis Percutaneous Nephrolithotripsy Study

During the past 10-15 years, important advancements have been witnessed in percutaneous nephrolithotomy (PCNL) techniques and instrumentation. The development of miniaturized PCNL techniques and modern laser technologies has contributed to lower complication rates, alongside changes in exiting strategies and postoperative drainage protocols. Ultrasound is increasingly utilized to create percutaneous access, and many medical centers have transitioned to the supine position for PCNL or perform Endoscopic Combined Intrarenal Surgery (ECIRS). All these developments have helped to individualize treatment strategies and to improve clinical outcomes for patients. However, there remains an ongoing discussion regarding the optimal indications and limitations of the different miniaturized PCNL techniques compared to standard PCNL and retrograde intrarenal surgery (RIRS).

This prospective observational study is organized under the auspices of the International Alliance of Urolithiasis (IAU) and focuses on the contemporary indications, surgical techniques, instrumentation, exiting strategies, efficacy, and risk factors for intraoperative and postoperative complications of PCNL. Participating investigators will collect data on the PCNL procedures performed in their respective clinical centers prospectively for a period of 12-18 months. The study will be initiated in each clinical center following formal approval from the IAU Scientific Committee, which will also announce the conclusion of the study.

Study Overview

• Status: Recruiting
• Conditions: Kidney Calculi; Urolithiasis
• Intervention / Treatment: Procedure: Percutaneous nephrolithotomi (PCNL)

Detailed Description

OBJECTIVES

Primary Study Objective:

To evaluate the contemporary indications, clinical efficacy, and safety profile of percutaneous nephrolithotomy (PCNL) for the treatment of renal stones.

Secondary Study Objectives:

To systematically assess intraoperative and postoperative complications of PCNL utilizing the standardized Clavien-Dindo classification system.

To identify and define specific independent risk factors contributing to intraoperative and postoperative complications following PCNL.

To execute a comparative efficacy analysis between miniaturized PCNL techniques and standard PCNL stratified by stone size and complexity.

The captured variables will undergo comprehensive statistical analysis to determine their respective effects on final procedural outcomes, stone-free rates, and perioperative complications. These parameters are categorized as follows:

Patient Preoperative Variables: Age, comorbidities, Body Mass Index (BMI), active anticoagulant/antiplatelet medications, stone configuration, presence of a solitary functioning kidney, and congenital musculoskeletal or anatomical renal abnormalities.

Preoperative Imaging and Diagnostics: Modalities utilized for surgical planning, stone density (Hounsfield units), cumulative stone size/burden, and stone number/location.

Preoperative Urinary Tract Status: Documented frequency of urinary tract infections (UTIs), identification of isolated bacterial strains, and protocols for preoperative antibiotic treatment (including specific drug types and duration).

Intraoperative Variables and Technical Access: Patient positioning (prone vs. supine variations), imaging modalities utilized for renal access puncture, definitive tract size, and the specific method of tract dilatation (balloon, metal telescopic, sequential fascial, or single-step/one-shot dilators).

Instrumentation and Efficacy Metrics: Type and size of the percutaneous access sheath, specific surgical instrumentation utilized (micro, mini, super-mini, ultra-mini, or standard PCNL), energy modalities used for lithotripsy fragmentation, and methods deployed for stone fragment extraction or evacuation.

Exiting Strategies and Postoperative Care: Choice of post-procedural drainage protocols (totally tubeless, tubeless, or standard nephrostomy tube placement, including tube type and size), time to drainage extraction, and total postoperative length of hospital stay.

Morbidity and Follow-Up: Documentation of procedural morbidity, with all adverse events classified according to the Clavien-Dindo system, alongside the subsequent management and treatment of any recorded complications.

DATA COLLECTION AND PROTOCOL MANAGEMENT Patients will be enrolled prospectively and consecutively across participating international sites, targeting a cumulative registry sample of up to 10,000 participants.

The International Alliance of Urolithiasis (IAU) Scientific Committee oversees and provides formal institutional approval for the initiation of data collection at each participating clinical center. Institutions participating in the registry must submit a formal application and cover letter to the IAU Scientific Committee.

Data collection is conducted via a secure, web-based data management system, with each approved clinical center utilizing a unique, personal username and password for system access. Every participating clinical site designates a local study coordinator responsible for ensuring accurate data entry and compliance.

To maintain data integrity, completeness, and quality control across all international centers, the IAU Scientific Committee has established a dedicated Audit Committee for continuous monitoring. Final data analysis and scientific reporting will be guided and coordinated directly by the IAU Scientific Committee.

• Study Type: Observational
• Enrollment (Estimated): 4000

Contacts and Locations

• Study Contact: Name: Iliya P Saltirov, DSc; Phone Number: 888723744 +359888723744; Email: iliya.saltirov@gmail.com
• Study Contact Backup: Name: Ognyan H Gatsev, PhD; Phone Number: 883490750 +359883490750; Email: gatsev@gmail.com

Study Locations

• Bulgaria
  • Sofia-Grad
    • Sofia, Sofia-Grad, Bulgaria, 1606
      • Recruiting
      • Foundation Endourology
      • Contact: Iliya P Saltirov, DSc; Phone Number: +359888723744; Email: iliya.saltirov@gmail.com
      • Contact: Ognyan H Gatsev, PhD; Phone Number: +359883490750; Email: gatsev@gmail.com
    • Sofia, Sofia-Grad, Bulgaria, 1606
      • Recruiting
      • Military Medical Academy, Department of Urology and Nephrology
      • Principal Investigator: Kemal Sarica, PhD
      • Principal Investigator: Guohua Zeng, PhD
      • Principal Investigator: Simon Choong, PhD
      • Contact: Iliya P Saltirov, DSc; Phone Number: +359888723744; Email: iliya.saltirov@gmail.com
      • Contact: Ognyan H Gatsev, PhD; Phone Number: +359883490750; Email: gatsev@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population consists of consecutive adult patients (18 years or older) diagnosed with renal or proximal ureteral calculi who are candidates for percutaneous stone surgery and are treated in real-world clinical practice settings. Participants are enrolled across 21 participating secondary and tertiary referral academic medical centers and hospitals globally, capturing a highly diverse and heterogeneous international population across multiple geographic regions

Description

Inclusion Criteria:

• Patient age 18 years or older at the time of enrollment.
• Diagnosed with single or multiple renal calculi (including complex and staghorn calculi) or proximal ureteral stones.
• Scheduled to undergo any primary or secondary percutaneous surgical stone intervention, including standard percutaneous nephrolithotomy (PCNL) or any of its miniaturized variations (Mini-PCNL, Ultra-mini PCNL, Super-mini PCNL, or Micro-PCNL).
• Voluntarily provided written informed consent for participation and data utilization.

Exclusion Criteria:

• Patient age under 18 years.
• Patients scheduled to undergo alternative primary treatment modalities for the targeted stone burden as a standalone procedure (e.g., retrograde intrarenal surgery [RIRS] or shockwave lithotripsy [SWL]).
• Presence of an active, untreated urinary tract infection (UTI) or clinical urosepsis at the time of the scheduled surgical procedure.
• Uncorrected severe coagulopathy or uncorrectable bleeding diathesis.
• Missing, incomplete, or unavailable medical charts or follow-up records rendering outcome assessment impossible.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Percutaneous nephrolithotripsy (PCNL)

Procedure: Percutaneous nephrolithotomi (PCNL); Patients included in this observational study undergo Percutaneous Nephrolithotomy (PCNL) for the treatment of renal calculi according to the established protocols of each participating center. The surgical procedure involves creating a percutaneous tract to the renal collecting system under ultrasound, fluoroscopic, or combined guidance. The study observes a wide spectrum of contemporary techniques, including standard-tract PCNL and miniaturized versions (Mini-PCNL), performed in either prone or supine positions. Specific procedural data are recorded, including the method of tract dilation (balloon, telescopic, or single-step), the type of lithotripsy energy used (laser, ultrasonic, or pneumatic), and postoperative drainage strategies (standard nephrostomy, tubeless, or stent-only). As an observational study, the choice of specific technique and equipment is determined by the treating surgeon based on clinical indications and institutional standards.; Other Names: PCNL; mini PCNL

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Primary Stone-Free Rate (SFR)	The primary efficacy outcome defined as the percentage of patients achieving clinical success at the 1-month follow-up evaluation. Stone-free status is defined as the complete absence of residual stone fragments or the presence of clinically insignificant residual fragments (CIRF) characterized as measuring $\le 3\text{ mm}$ in maximum diameter. Efficacy and fragment clearance will be verified using the participating center's standard postoperative imaging protocols, which include kidney-ureter-bladder (KUB) radiography, renal ultrasonography, or non-contrast computed tomography (NCCT) scans.	1 month postoperatively.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Complication Rate	The incidence and severity of postoperative adverse events and complications will be systematically recorded and graded according to the standardized Clavien-Dindo classification system. The scale ranges from Grade I (minor deviations from the normal postoperative course without need for pharmacological or surgical intervention) to Grade V (patient mortality). The final reported metrics will include the overall percentage of patients experiencing any complication (Grades I-V) and the rate of severe major complications (defined as Clavien-Dindo Grade $\ge$ III) within the 1-month postoperative follow-up period.	Up to 30 days postoperatively
Perioperative Hemoglobin Drop	The absolute change in serum hemoglobin levels measured in grams per deciliter ($g/dL$). It is calculated as the mathematical difference between the patient's baseline preoperative hemoglobin value (obtained within 48 hours prior to surgical incision) and the lowest recorded postoperative hemoglobin value obtained within the first 24 hours following the procedure. This metric serves as an objective surrogate marker for perioperative blood loss.	Within 24 hours postoperatively
Length of Hospital Stay (LOS)	The total duration of the inpatient hospital stay calculated in days. The count begins on the day of the percutaneous surgical procedure and concludes on the exact date of formal medical discharge from the urology department. A longer stay typically reflects the management of postprocedural complications or prolonged drainage requirements.	From the day of surgery/admission until formal hospital discharge, assessed up to 14 days
Total Operative Time	The cumulative duration of the surgical intervention measured continuously in minutes. The time frame is defined as the interval starting from initial patient positioning and the commencement of mandatory diagnostic cystoscopy/ureteral catheterization, up to the final secure placement of percutaneous drainage (nephrostomy tube/ureteral stent) and dressing application.	During the surgical procedure
Postoperative Change in Renal Function	The longitudinal evaluation of renal excretory capacity. This is determined by comparing preoperative baseline blood samples with follow-up laboratory values obtained at 1 month postoperatively. The primary markers analyzed will be serum creatinine levels ($mg/dL$ or $\mu mol/L$) and the estimated Glomerular Filtration Rate (eGFR), calculated using the standardized CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation to assess any transient or permanent functional impairment.	Preoperatively up to 1 month postoperatively

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Primary Percutaneous Renal Access Success Rate	The technical success rate of gaining definitive percutaneous access into the renal collecting system. Success is defined as the correct and safe placement of the working guidewire and the subsequent percutaneous tract sheath into the targeted renal calyx or renal pelvis, allowing for the successful introduction of the nephroscope. This metric will evaluate and compare the efficacy of different imaging guidance modalities (pure ultrasound-guided puncture versus conventional fluoroscopy guidance versus dual/combined tactile guidance) and will be reported as the overall percentage of successfully established tracts across the treatment cohorts.	During the surgical procedure
Perioperative Blood Transfusion Rate	The overall percentage of patients requiring the administration of allogeneic packed red blood cells (PRBC) or other homologous blood products during the intraoperative period or within the 30-day postoperative window. The decision to transfuse will be based on standardized institutional clinical criteria, including an acute drop in serum hemoglobin levels (typically below $7\text{-}8\text{ g/dL}$) or the presence of clinical symptoms of severe anemia/hemodynamic instability. This metric will be reported as a categorical outcome (transfusion required vs. not required) to evaluate the safety profile across the different PCNL tract sizes and techniques.	Up to 30 days postoperatively
Intraoperative Radiation Exposure Time	The total duration of fluoroscopy utilization recorded continuously during the surgical procedure, measured in minutes (or seconds). This metric captures the cumulative time the fluoroscopy pedal is activated to achieve renal collection system localization, guide the puncture needle, monitor tract dilatation, and verify stone clearance. It will be utilized to quantify and compare the radiation burden between conventional fluoroscopy-guided cases, dual-guidance protocols, and pure ultrasound-guided access (where exposure time is expected to be zero).	During the surgical procedure

Collaborators and Investigators

• Sponsor: Foundation Endourology
• Collaborators: The International Alliance of Urolithiasis
• Investigators: Study Chair: Kemal Sarika, PhD, Sancaktepe Training and Research Hospital, Istanbul, Turkiye; Study Chair: Guohua Zeng, PhD, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Study Chair: Simon Choong, PhD, Institute of Urology, University College London Hospitals, London, United Kingdom

Study record dates

Study Major Dates

• Study Start (Actual): August 15, 2019
• Primary Completion (Estimated): June 15, 2026
• Study Completion (Estimated): June 15, 2026

Study Registration Dates

• First Submitted: May 25, 2026
• First Submitted That Met QC Criteria: May 30, 2026
• First Posted (Actual): June 3, 2026

Study Record Updates

• Last Update Posted (Actual): June 3, 2026
• Last Update Submitted That Met QC Criteria: May 30, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Efficacy; Urolithiasis; Postoperative Complications; Kidney Stones; Percutaneous Nephrolithotomy; Mini-PCNL; Standart PCNL
• Additional Relevant MeSH Terms: Urogenital Diseases; Pathologic Processes; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urinary Calculi; Nephrolithiasis; Pathological Conditions, Signs and Symptoms; Kidney Calculi; Postoperative Complications; Urolithiasis
• Other Study ID Numbers: FoundatioEndourology

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data collected during the study, including data dictionaries, will be made available to researchers whose proposed use of the data has been approved by the IAU Scientific Committee. This is intended for the purpose of further academic research and meta-analyses to improve patient care in endourology
• IPD Sharing Time Frame: 6 months after publication of the primary manuscript 36 months after publication.

IPD Sharing Access Criteria

Qualified academic researchers and clinicians with a methodologically sound research proposal that aims to advance the field of endourology and stone disease management." What: De-identified individual participant data (IPD) that underlie the results reported in the published articles, including the study protocol, statistical analysis plan (SAP), and data dictionary.

How: Proposals should be submitted directly to the corresponding author (Prof. Iliya Saltirov, saltirov@vma.bg). All requests will be reviewed by the IAU Scientific Committee to ensure ethical standards and scientific validity. To gain access, requesters must sign a formal Data Access Agreement (DAA) to protect participant confidentiality and ensure data security.

• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No