The goal of this observational study is to investigate the feasibility of ultrasound-guided percutaneus nephrolithotomy in patients with kidney stones. The main question's it aims to answer are:

Does the use of ultrasound in percutaneus nephrolithotomy affect stone free rates, defined by no stone or stone <2mm, on follow up visit?

Does the use of ultrasound in percutaneus nephrolithotomy affect complication rates, categorized by Clavien system?

Researchers will compare ultrasound-guided percutaneus nephrolithotomy to traditional nephrolithotomy using fluoroscopy to see if outcomes differ.

Participants will be chosen for any of the above interventions at surgeon's discretion.

Percutaneous nephrolithotomy (PCNL) is a minimally invasive procedure for removal of kidney stones that has traditionally been done using fluoroscopy for guidance. This study aims to explore if PCNL can be done safely using ultrasound as a replacement for fluoroscopy to decrease radiation exposure.

This study is a prospective cohort comparing subjects that undergoes radiation free and non-radiation free PCNLs performed by a single surgeon at UCSD Health. All cases are evaluated for ultrasound feasibility, and some have to be converted to fluoroscopy at surgeon's discretion. Information about the risks of the procedure including bleeding, infection, incomplete stone removal and injury to the kidney is given to each participant. All surgeries are performed by an experienced urologist with a history of successful ultrasonography interpretation and fluoroscopy is always accessible in the OR in case ultrasonography would not offer good enough imaging quality for the procedure to be completed in a safe and successful manner. The study does not affect the choice of imaging modality used for individual procedures but only looks at characteristics and outcomes of already performed surgeries.

Subjects are selected from the schedule in Epic and divided into three groups, radiation free PCNLs, converted cases and planned PCNLs with fluoroscopy based on information provided in the operative note from each procedure. All subjects that appear on the schedule are included in this study. Data is collected from a US electronic medical record system (Epic), using an online database tool, RedCap. The data consists of 15 cases that have undergone radiation free PCNL, 15 cases that were converted to fluoroscopy, 32 cases that were planned and performed with fluoroscopy. 5 operations had to be aborted. Data is divided into patient demographics (age, gender, ethnicity, BMI, past medical history, anticoagulants), pre-operative data (ASA class, pre-op tubes, laterality, total stone burden, number of stones, stone location, pre-op urine culture, reason for radiation or radiation-free procedure), operative data (imaging modality, access location, number of access attempts, tract dilation size, end of tube case, estimated blood loss, end of case residual stones, total time in operating room (OR), total time under fluoroscopy) and postoperative data (admissions, hospital length of stay, inpatient course, discharge antibiotics, 30 day complications, post-op imaging, post-op stone size, need for additional procedure, post-op creatinine levels and GFR).

Inclusion Criteria:

Scheduled percutaneus nephrolithotomy by Dr. Roger Sur between 2022 and 2025 at UCSD Hillcrest.

Exclusion Criteria:

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General population with kidney stones larger than 20mm.