Trial Parameters
Brief Summary
The goal of this observational study is to learn about the benefit of using RetroPerc® in obtaining renal access for percutaneous nephrolithotomy. The device is already used in routine clinical practice by urologists around the country. Participants who are already scheduled to undergo percutaneous nephrolithotomy as part of their regular care will be asked to participate.
Eligibility Criteria
Inclusion Criteria: * Renal stone or total linear sum of 1.5-3cm cm in maximum dimension (largest diameter in axial or coronal)--- multiple stones should be summed to determine stone size. * Age \>=18 years of age * Gender: both men and women included. * Ethnic background: all ethnicities will be included in the study population and the specific ethnic diversity present in the study population will reflect the geographic distributions of the participating institutions. * Plan for PCNL in the supine position Exclusion Criteria: * Active pregnancy * BMI \>45 * Severe Hydronephrosis - renal pelvis diameter \> 20mm * Flank window \< 4 cm are ineligible for puncture * Previous ipsilateral PCNL * Currently with "useful" nephrostomy tube on ipsilateral side * Uncorrectable coagulopathies * Untreated urinary tract infection * Subjects with significant morbidities such as American Society of Anesthesiologists (ASA) score ≥ 4, severe spinal cord injuries, severe cardiopulmonary insufficiency, un