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Increasing Body Mass Index Steepens the Learning Curve for Ultrasound-guided Percutaneous Nephrolithotomy
David B Bayne1, Manint Usawachintachit2, David Tzou1
1Department of Urology, University of California, San Francisco, San Francisco, CA.
Urology
|August 6, 2018
Summary
Higher body mass index (BMI) and fewer cases impact the success of ultrasound-guided percutaneous nephrolithotomy (PCNL). Increasing BMI presents challenges for renal access during this procedure, affecting the learning curve for surgeons.
Area of Science:
- Urology
- Medical Imaging
- Surgical Education
Background:
- Ultrasound-guided percutaneous nephrolithotomy (PCNL) is an effective treatment for nephrolithiasis.
- A key concern is reduced imaging efficacy in obese patients.
- Fluoroscopy-guided PCNL is a comparable alternative.
Purpose of the Study:
- To determine the impact of body mass index (BMI) on the learning curve for successful ultrasound-guided PCNL.
- To assess the relationship between BMI, surgical experience, and ultrasound-guided renal access success.
Main Methods:
- Prospective cohort study of 150 patients undergoing ultrasound-guided PCNL.
- Data collected: renal access success, patient BMI, and clinical outcomes.
- Nonparametric LOWESS regression modeling used to analyze BMI groups (<30, 30-40, >40).
Main Results:
- BMI (P=.010; OR 0.93) and case number (P<.001; OR 1.03) significantly correlated with ultrasound success.
- Obesity (BMI >40) showed a downward and right-shifted learning curve for renal access.
- Sex, age, hydronephrosis, stone type, puncture location, and stone size did not significantly affect access success.
Conclusions:
- Patient BMI and surgical case number influence the learning curve for ultrasound-guided PCNL.
- Higher BMI poses greater challenges for achieving successful renal access.
- Experience and patient BMI are critical factors in mastering ultrasound-guided PCNL.
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