RETRO Study (RETrograde Renal Access Outcomes)

Eligibility 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
• * 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.