Randomized Controlled Trial to Compare the Operative Outcomes and Complications of Mini-percutaneous Nephrolithotomy (mini-PCNL) Versus Standard PCNL

Presurgical management will follow the standard of care and patients with active urinary tract infections will be treated prior to kidney stone surgery. After the informed consent process, the subject will be asked to complete the Wisconsin Stone Quality of Life Index (WISQOL), an externally validated and internally consistent questionnaire designed specifically for kidney stones patients. All patients should receive a computerized tomography (CT) scan prior to their procedure as standard of care for assessment of stone burden and access planning. This preoperative imaging will be assessed and scored using the standardized STONE scoring system, which has been validated for predicting treatment success and perioperative complications following PCNL.

Prior to their procedure patients will be randomized to receive one of the two interventions outlined above, only study subjects will be blinded to the randomization. Randomization will be conducted centrally for each site to ensure balance of PCNL and mini-PCNL using the CCF-Redcap randomization module to ensure proper randomization between sites. Randomization can occur at any time after enrollment prior to surgery. Study subjects will be selected from a patient pool where PCNL or mini-PCNL would be considered equally viable alternative Standard of Care procedures for treatment of kidney stone disease, with neither procedure presenting any benefit over the other. The randomization of procedure for this pool of study subjects was to guarantee that an equal number of both procedures were performed in the trial throughout all centers.

Patients choosing to participate in this research study will not be informed of which procedure they received to minimize any bias regarding postoperative pain and quality of life scores. No changes to the disclosure process will be made for any other variations or complications during their procedure outside of the research study interventions. Due to the time between the initial surgical procedure and postoperative follow-up visit there is a risk of unintentional unblinding by other providers involved with the care of study patients and access to their medical records. As such patients will be asked at the time of their follow-up visit if they remained blinded to their procedure type. Whenever possible patients should remain blinded but unblinding is not an exclusion criterion as the primary endpoint, change in hemoglobin, should not be affected by this knowledge.

A pre-operative complete blood count and basic metabolic panel will be obtained. Two endoscopic stone procedure types will be investigated in this study. The first, a standard percutaneous nephrolithotomy (sPCNL)- performed using a 30 Fr access sheath following balloon dilation. The second, a mini percutaneous nephrolithotomy (mPCNL)- performed using an 18 Fr access sheath following either balloon dilation or dilation using a single step metal dilator. Both procedures will be performed under general anesthesia with the patient in prone position. Access technique (triangulation method, ultrasound guided, or endoscopically guided) will be at the discretion of the attending surgeon. Stone lithotripter type (pneumatic, ultrasonic, or laser) and retrieval method (basket, forceps) will similarly be at the discretion of the urologist. Placement of ureteral stents will be left up to the discretion of the surgeon. Placement of nephrostomy tubes will be recorded as a protocol deviation and the indication for placement recorded. Whenever possible a single access tract will be used for the procedure and if multiple access sites are required it will be recorded as a protocol deviation. Following completion of the procedure and closure of the access tract, pressure will be applied to the surgical site for one minute. Patients with plans for a staged bilateral PCNL should only be enrolled for their first operation and should complete the quality-of-life questionnaire and imaging requirements described below prior to their second procedure.

Renal pelvis pressure monitoring is not part of the standard of care and is included as an outcome for research purposes only. There is no additional risk to the patient when monitoring this pressure and patients will be informed of this during the informed consent process.