IAU Percutaneous Nephrolithotripsy Study

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.

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.

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.

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.

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.

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.

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.

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).