RETRO Study (RETrograde Renal Access Outcomes)

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, uncontrolled diabetes, neurological disorders, bedbound, anticipated life expectancy less than 5 years, or any other comorbidity, that in the opinion of the principal investigator could represent an increased peri-operative risk for the subject; * Ipsilateral partial nephrectomy * History of ipsilateral ureteral reimplantation or ureteral reconstruction; * History of Simple or radical prostatectomy * History of cystectomy * History of calyceal diverticula stone; * History of renal donation or transplant; * Any other previous pelvic surgical treatment that could put the subject at greater procedural complication risk or technical difficulty; * Ureteral ipsilateral stricture, untreated; * Ureteral stricture, untreated (not to include "tight" ureter); * Any other bladder, ureteral or kidney congenital genitourinary abnormalities (e.g. Horseshoe kidney, ipsilateral duplicated or partially duplicated collecting system, ipsilateral ectopic kidney, cross-fused ectopia, bifid renal pelvis with no horizontally directed calyces, solitary kidney, etc.) preventing the ability to direct a puncture laterally or render the subject stone free; * Have participated in any other clinical trial within the last 3 months, and/or plans to participate in any other investigational or invasive clinical trial during this study; * If female, breast-feeding, or if childbearing age, is not using contraception between screening and 90 days post-op; * Subject has current or recent history of substance abuse (e.g. recreational drugs, narcotics, or alcohol) requiring intervention; * Is a prisoner or ward of the state; * Is unable to meet the treatment and follow up protocol requirements.