RETRO Study (RETrograde Renal Access Outcomes)

Retrograde nephrostomy access is well established as a safe method for nephrostomy creation and thus this study aims to perform a standard of care study. The device is already available, on the shelf, and used in routine clinical care. However, the study aims to take a closer look in a prospective fashion at this access technique to better understand specific variables that are not available on retrospective review of cases that have already undergone PCNL with this technique.

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.